Hello 2024, The first tester tested on 10 October **2022**. , Hello Codeforces, We are very glad to invite you to participate in
[contest:1919], which will, ], [user:bensonlzl,2024-01-02] for testing a subset of the problems in 2022. -
[user:MikeMirzayanov,2023
→ Pay attention
Before contest
Codeforces Round 940 (Div. 2) and CodeCraft-23
37:17:59
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Codeforces Round 940 (Div. 2) and CodeCraft-23
37:17:59
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Results
1.
Hello 2024 Hello Codeforces,
We are very glad to invite you to participate in [contest:1919], which will start on [contest_time:1919]. You will be given **8 problems** and **2.5 hours** to solve them. One of the problems will be divided into two subtasks. The round will be rated for everyone. There will be at most 2024 interactive problems, so please read the [guide for interactive problems](https://codeforces.com/blog/entry/45307) before the contest.
All the problems are written and prepared by me.
<spoiler summary="Spoiler">
The first tester tested on 10 October **2022**.
</spoiler>
We would like to give our sincere thanks to:
- [user:errorgorn,2024-01-02] for his wonderful coordination!
- [user:Alexdat2000,2024-01-02] for translating problem statements.
- [user:dario2994,2024-01-02] for coming up with the solution to one of the problems.
- [user:conqueror_of_tourist,2024-01-02], [user:iLoveIOI,2024-01-02], [user:Um_nik,2024-01-02], [user:oolimry,2024-01-02], [user:thenymphs...
Announcement of Hello 2024
2.
AlphaCode (DeepMind) Solves Programming Problems on Codeforces <img src="/predownloaded/99/08/99083f12762004fb2f7278177262dd577e3f19cd.png" style="float:right; width:300px; margin:0;"/>
Hello, community.
Today DeepMind announced a new achievement of AI. And it is directly related to what we love — programming problems.
They have developed AI capable of solving some competitive programming problems! The future has arrived.
You should read solutions of [user:SelectorUnlimited,2022-02-02], [user:WaggleCollide,2022-02-02], and [user:AngularNumeric,2022-02-02] solutions. All solutions are written automatically. The only input for writing solutions is a problem statement in English.
Details can be read at the link https://deepmind.com/blog/article/Competitive-programming-with-AlphaCode
Apparently, if these accounts would take part in real competitions, then their rating would be about 1300.
<center>
<img src="https://i.blogs.es/a2119c/terminator-2/1366_2000.jpg" style="width:450px;"/><br>
<small>Terminator is ready to take p...
; width:300px; margin:0;"/> Hello, community. Today DeepMind announced a new
achievement of AI
3.
Goodbye 2021. Hello 2022! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/>
Hello Codeforces!
Oh yes, 2021 ends! I recently realized that 2022 is pronounced like "2020 too". Not that. I want a completely different year!
Anyway, we did a nice job this year. I hope we have pleased you with interesting problems.
Thanks to the round coordinators and writers! You make our community richer. Please make us happy in 2022!
I wish you all interesting tasks and brilliant solutions! I wish you error-free code and wish us only rated rounds :-)
Hello, 2022!
And we have traditional gifts!
#### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature
Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for.
You can change your han...
Goodbye 2021. Hello 2022!, to the round coordinators and writers! You make our community richer. Please
make us happy in2022!, Hello Codeforces!, Hello, 2022!, Oh yes, 2021 ends! I recently realized that 2022 is pronounced like "2020 too".
Not that. I want a
4.
Goodbye 2022. Hello 2023! <img src="/predownloaded/f4/1f/f41ff0beb745fb2f84a55d9f2cc451273efc6267.jpg" style="width:300px; float:right; margin: 0 1em 1em 1em"/>
Dear Santa Claus. Please make 2023 a happy year, not just that. Please, we all need this.
Hello, 2023!
And we have traditional gifts!
#### <img src="https://assets.codeforces.com/images/wand.png"/> Change Handle Feature
Hurry! Only until the 10th of January, you can change your handle (<b>but only once</b>)! Note that it will be possible to roll back the changes or change the handle again only _after a year_. Be careful what you wish for.
You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with an old handle would automatically redirect to the actual profile.
Again, this year if you took part in at least 10 rounds you can request a handle of an _inactive_ participant. It means that the participant should have a period of activity on Codeforces
of...
Goodbye 2022. Hello 2023!, Hello, 2023!
5.
Good Bye 2022: 2023 is NEAR "It's been a long time since I came here, and I've really been through a lot." Koxia muses as she chatted idly with Mahiru.
Now that the Winter Festival is approaching. Among the flash of fireworks, in the chimes of the New Year, what is waiting for them to encounter?
Armed with girlish courage, they stepped onwards.
Hello Codeforces!
We ([user:Nanako,2022-12-27], [user:m_99,2022-12-27], [user:huangxiaohua,2022-12-27], [user:SteamTurbine,2022-12-27], [user:triple__a,2022-12-27], [user:Nezzar,2022-12-27]) are very pleasured to invite you to take part in [contest:1770], which will take place in [contest_time:1770]!
This round consists of **8 tasks** waiting for you to solve in **150 minutes**, and will be rated for everyone!
On behalf of the author team, please allow me to express our sincere thanks to:
* [user:errorgorn,2022-12-27], for useful guidance and brilliant advice during the coordinati...
Good Bye 2022: 2023 is NEAR, Hello Codeforces!
6.
Educational Codeforces Round 121 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1626] [contest:1626] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-01-15] Dalabaev, Vladimir [user:vovuh,2022-01-15] Petrov, Ivan [user:BledDest,2022-01-15] Androsov, Mak...
Hello Codeforces! On [contest_time:1626] [contest:1626] will start. Series of
Educational
Announcement of Educational Codeforces Round 121 (Rated for Div. 2)
7.
CodeTON Round 2 Hello, Codeforces!
A wonderful summer holiday! After College Entrance Examination, we are extremely delighted to invite you to our second round, [contest:1704], which will be held on [contest_time:1704]. **Note the unusual start time of the round.**You are given **8 problems** and **2.5 hours** to solve them.
All problems were written and prepared by [user:Cirno_9baka,2022-07-23], [user:CoupDeGrace,2022-07-23], [user:Heltion,2022-07-23], [user:ODT,2022-07-23], [user:Yakumo_Ran,2022-07-23], [user:farmerj,2022-07-23], [user:flowerletter,2022-07-26], [user:izlyforever,2022-07-23], [user:kuangbin,2022-07-23], [user:mejiamejia,2022-07-23], [user:ugly2333,2022-07-23] and me.
Task statements and editorials will also be available in Chinese (Simplified) and Chinese (Traditional) after the contest.
We are sincerely thankful for the help provided by:
- [user:3.141592653,2022-07-25], [user:emorgan5289,2022-07-25], [user:errorgorn,2022-07-25], [user:SevenDawns,2022-07-25], [user:pr...
Hello, Codeforces! A wonderful summer holiday! After College Entrance
Examination, we are
Announcement of CodeTON Round 2 (Div. 1 + Div. 2, Rated, Prizes!)
8.
Good Bye 2022, Hello 2023! <img src="/predownloaded/cf/40/cf40c72e68b2aee5005a91f39e1d3404d917617b.jpg" style="float:right; margin:0 1em 1em 1em;"/>
Hello, Codeforces!
The year 2022 is finally coming to an end. Let's be clear. It's been a terrible year. Tomorrow I will make a wish, and you can easily guess which one.
I am writing these lines, and in a few minutes the Good Bye 2022 round will begin. And this inspires optimism and even pride in the community. Despite all these difficulties and troubles, we make rounds together and participate in them. Let's be grateful. And for this, let's say symbolic thanks to 2022 and a lot assistants: coordinators, problem writers, testers, participants and sponsors. We are many and we are together.
Can I have a little more detail on the Codeforces team?
Let me separately say thanks and words of admiration for the work of the coordinator of coordinators [user:KAN,2022-12-30] and the senior developer [user:geranazavr555,2022-12-30]. Both of you bring a lot to Cod...
Good Bye 2022, Hello 2023!, coordinators [user:KAN,2022-12-30] and the senior developer
[user:geranazavr555,2022-12-30]. Both of you bring, Hello, Codeforces!, I am writing these lines, and in a few minutes the Good Bye 2022 round will
begin. And this, I send thanks to [user:Una_Shem,2022-12-30]: in the difficult conditions of
broken global logistics, Thanks to [user:unreal.eugene,2022-12-30] for contributing to the development
and [user:kuviman, The year 2022 is finally coming to an end. Let's be clear. It's been a terrible
year. Tomorrow I, Who I will not say thank you to, it's cheaters! Ugh, to be like that. Please
stay in2022.
9.
Codeforces Global Round 19 Hello, Codeforces! (づ｡◕‿‿◕｡)づ ❤
On [contest_time:1637] we will host [contest:1637]. **<img src="/predownloaded/2e/e2/2ee2f0f95f05aae6ca6f47812dae2dc2aabf277b.png" style="width: 200.0px;float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">**
It is the first round of a 2022 series of [Codeforces Global Rounds](https://codeforces.com/blog/entry/65002) supported by XTX Markets. The rounds are open and rated for everybody.
The presents for this round:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The presents for the 6-round series in 2022:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
The problems w...
Hello, Codeforces! (づ｡◕‿‿◕｡)づ ❤ On [contest_time:1637] we will host
[contest:1637]. **
Announcement of Codeforces Global Round 19
10.
Hello 2022 Hi, Codeforces! Happy New Year!
Я рад пригласить Вас на соревнование [contest:1621], которое пройдёт в [contest_time:1621]. У Вас будет **$2$ часа $15$ минут** на решение задач. **Раунд будет рейтинговым для всех.**
Все задачи придуманы мной. Я рад поблагодарить [user:74TrAkToR,2022-01-01] за великолепную координацию раунда и [user:MikeMirzayanov,2022-01-01] за платформы Codeforces и Polygon.
- Спасибо [user:isaf27,2022-01-01], [user:Nebuchadnezzar,2022-01-01], [user:MichsSS,2022-01-01], [user:TadijaSebez,2022-01-01], [user:ijxjdjd,2022-01-01], [user:Um_nik,2022-01-01], [user:DanShaders,2022-01-01], [user:I_Remember_Olya_ashmelev,2022-01-01], [user:Monogon,2022-01-01], [user:errorgorn,2022-01-01], [user:Mr.Robot_28,2022-01-01], [user:AlexLuchianov,2022-01-01], [user:Kirill22,2022-01-01], [user:flamestorm,2022-01-01], [user:Prokhor08,2022-01-01], [user:romanasa,2022-01-01], [user:Dragonado,2022-01-01], [user:arseny.__.,2022-01-01], [user:magnus.hegdahl,2022-01-01], [user:Olly_Z...
Hello 2022, рейтинговым для всех.** Все задачи придуманы мной. Я рад поблагодарить
[user:74TrAkToR,2022-01-01] за, ,2022-01-01] for excellent round coordination and [user:MikeMirzayanov,2022
-01-01] for great, - Thanks to [user:isaf27,2022-01-01], [user:Nebuchadnezzar,2022-01-01],
[user:MichsSS,2022-01-01, - Спасибо [user:isaf27,2022-01-01], [user:Nebuchadnezzar,2022-01-01],
[user:MichsSS,2022-01-01, 1. [user:tourist,2022-01-03], 10. [user:Rebelz,2022-01-03], 2. [user:maroonrk,2022-01-03], 3. [user:Radewoosh,2022-01-03], 4. [user:Benq,2022-01-03], 5. [user:djq_fpc,2022-01-03], 6. [user:mnbvmar,2022-01-03], 7. [user:ainta,2022-01-03], 8. [user:mhq,2022-01-03], 9. [user:ecnerwala,2022-01-03], All problems are authored by me. I would like to thank [user:74TrAkToR,2022
-01-01] for excellent, Все задачи придуманы мной. Я рад поблагодарить [user:74TrAkToR,2022-01-01] за
великолепную
Announcement of Hello 2022
11.
Codeforces Round #844 (Div. 1 + Div. 2) Hello!
Welcome to the [contest:1782] that will start on [contest_time:1782]. It will be a combined rated round for both divisions and open to everyone.
This round is a mirror of VK Cup 2022 Elimination — annual programming championship for Russian-speaking competitors organized by VK. VK Cup [started in 2012](https://codeforces.com/vkcup2012) and has grown to be a five-track competition in competitive programming, Mobile, ML, Go, and JavaScript.
All the problems are authored and prepared by me. Thanks to [user:KAN,2023-01-13], [user:errorgorn,2023-01-13], [user:lperovskaya,2023-01-13], [user:dario2994,2023-01-15], [user:Monogon,2023-01-15], [user:Arpa,2023-01-15] for making this round better.
You will be given 8 problems and 3 hours to solve them.
**UPD**: [Editorial](https://codeforces.com/blog/entry/111783)
Congratulations to the winners:
1. [user:orzdevinwang,2023-01-24]
2. [user:noimi,2023-01-24]
3. [user:Radewoosh,2023-01-24]
4. [user:gamegame,2023-01-24]
...
Hello! Welcome to the [contest:1782] that will start on [contest_time:1782]. It
will be a
Announcement of VK Cup 2022 - Отборочный раунд (Engine)
12.
Hello 2023 Hello Codeforces!
I am pleasured to invite you to take part in [contest:1779], which will take place in [contest_time:1779]!
This round consists of $8$ tasks waiting for you to solve in $150$ minutes, and will be rated for everyone!
As an author, please allow me to express my sincere thanks to:
* [user:dario2994,2022-12-31], for being responsive, his amazing guidance, helping me prepare one of the problems and his truly wonderful coordination!
* [user:KAN,2022-12-31], for rechecking and translating the round!
* [user:wxhtzdy,2022-12-31], for proposing ~~rejected~~ tasks and discussing every problem with me
* [user:giove,2022-12-31], for a problem idea which fits a gap.
* [user:Um_nik,2022-12-31], [user:gamegame,2022-12-31], [user:JovanB,2022-12-31], [user:Marko,2022-12-31], [user:cip999,2022-12-31], [user:nweeks,2022-12-31], [user:NemanjaSo2005,2022-12-31], [user:Sofija06,2022-12-31], [user:Fikuss,2022-12-31], [user:badlad,2022-12-31], [user:Jovan08,2022-12-31], for p...
Hello 2023, of the problems and his truly wonderful coordination! * [user:KAN,2022-12-31],
for rechecking and, Hello Codeforces! I am pleasured to invite you to take part in [contest:1779],
which will take
Announcement of Hello 2023
13.
Codeforces Round #767 (Div. 1, Div. 2) #### Hello Codeforces!
[user:magnus.hegdahl,2022-01-18] and I are glad to invite you to [contest:1628] and [contest:1629] which will be held on [contest_time:1629]! This round is rated for both divisions.
In each division there will be **6 problems** and **2 hours** to solve them.
We would like to thank the following amazing people:
- [user:74traktor,2022-01-18] for great coordination of the round and translating the statements!
- [user:efimovpaul,2022-01-18], [user:agrayush13,2022-01-18], [user:ak2006,2022-01-18], [user:BidoTeima,2022-01-18], [user:QuangBuiCP,2022-01-20], <a class="rated-user user-blue" href="/profile/mesanu" title="mihai">mesanu</a>, <a class="rated-user user-blue" href="/profile/_Vanilla_" title="chad">_Vanilla_</a>, [user:down,2022-01-18], [user:FedShat,2022-01-18], [user:gupta_samarth,2022-01-21], [user:namanbansal013,2022-01-21], [user:MoonKnight.,2022-01-18], [user:stefdasca,2022-01-18], [user:AlperenT,2022-01-18], [user:DivanCode,2022-01-20], [user...
#### Hello Codeforces! [user:magnus.hegdahl,2022-01-18] and I are glad to
invite you to [contest
Announcement of Codeforces Round 767 (Div. 1)
Announcement of Codeforces Round 767 (Div. 2)
14.
Codeforces Global Round 21 Hello Codeforces!
On [contest_time:1696] we will hold [contest:1696]. **<img src="/predownloaded/2e/e2/2ee2f0f95f05aae6ca6f47812dae2dc2aabf277b.png" style="width: 200.0px;float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">**
It is the third round of a 2022 series of [Codeforces Global Rounds](https://codeforces.com/blog/entry/65002). The rounds are open and rated for everybody.
The prizes for this round:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The prizes for the 6-round series in 2022:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
Thanks to XTX, which in 2022 supported the global ...
Hello Codeforces! On [contest_time:1696] we will hold [contest:1696]. **
Announcement of Codeforces Global Round 21
15.
Codeforces Round #777 (Div. 2) Привки, Кодефорсес (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧
------------------
_(Hello, Codeforces on Russian)_
<img src="/predownloaded/b1/4a/b14a9b0bf490c91e37290a3dca53f53b9f6680b0.jpg" style="float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">
[user:Igorbunov,2022-03-10] and **I** are happy to invite you to participate in [contest:1647], all the tasks of which will be about a little girl Madoka. It will take place on [contest_time:1647]. The round will be **rated** for all participants with rating strictly lower than **2100**. You will have **2 hours** to solve **6 problems**.
I would also like to express my gratitude to the following people:
- To our cute coordinator [user:Artyom123,2022-03-10].
- To cute testers for cute feedback on cute tasks: [user:FelixDzerzhinsky,2020-09-14], [user:lesssia,2022-03-09], [user:eyakm1,2022-03-09], [user:_Vanilla_,2022-03-09], [user:morzer,2022-03-09], [user: welleyth,2022-03-09], [user:TeaTime,2022-03-09], [user:Dart-Xeyter,2022...
Привки, Кодефорсес (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧ ------------------ _(Hello, Codeforces on
Russian)_
Announcement of Codeforces Round 777 (Div. 2)
16.
Invitation to Good Bye 2021: 2022 is NEAR Hello Codeforces!
We have a pleasure to invite you to [Good Bye 2021](https://codeforces.com/contests/1616), which will take place on [contest_time:1616]. You will have **2 hours** to solve the problems. The round will be rated for participants of both divisions.
The problems for this round were prepared by [user:300iq,2021-12-29], with the help of excellent coordinators [user:KAN,2021-12-29] and [user:74TrAkToR,2021-12-29].
We would like to thank all the testers, who made this round possible: [user:gamegame,2021-12-29], [user:thenymphsofdelphi,2021-12-29], [user:ko_osaga,2021-12-29], [user:golions,2021-12-29], [user:Ashishgup,2021-12-29], [user:izban,2021-12-29], [user:prabowo,2021-12-29], [user:74TrAkToR,2021-12-29], [user:Devil,2021-12-29], [user:manish.17,2021-12-29], [user:Discombobulated,2021-12-29], [user:minhcool,2021-12-29], [user:AlFlen,2021-12-29], [user:Utkarsh.25dec,2021-12-29], [user:NemanjaSo2005,2021-12-29], [user:wxhtzdy,2021-12-29], [user:ajit,2021-12-29], [...
Invitation to Good Bye 2021: 2022 is NEAR, Hello Codeforces!
Announcement of Good Bye 2021: 2022 is NEAR
17.
Codeforces Sponsored by TON! <img src="/predownloaded/12/a0/12a02d5f16863f9f45bba4c6cd4224f0f2178b94.png" style="float:right; margin: 0 1em 1em 1em; width: 400px;"/>
Hello, Codeforces.
We have exciting news! Look at the logo. See the changes?
Yes, we are happy to announce our new sponsor and partner – the TON Foundation!
We appreciate their support!
The Open Network (TON) is a fully decentralized layer-1 blockchain designed by Telegram to onboard billions of users. The TON Foundation is aimed to further develop and advance the TON Blockchain and its related products for a mass audience.
Andrew Rogozov, founding member at the TON Foundation, says, "<i>We strongly believe in the idea of competitive programming itself, because it is in the TON Blockchain DNA.</i>" The TON Blockchain protocol was designed by Nikolai Durov — who is a two-time ICPC world champion, a three-time IMO gold medalist, a multiple IOI medalist, and a co-founder of Telegram — and other winners of international competitions...
; margin: 0 1em 1em 1em; width: 400px;"/> Hello, Codeforces. We have exciting
news! Look at the
18.
Codeforces: Results of 2023 [Annual Report] Hello, Codeforces.
Let's recall 2023, shall we?
In this post, I want to summarize this year. You know, a lot of terrible things happen in the world, and personally, this year was the hardest and most sorrowful for me. But today, we'll remember something else. We'll remember what this year was like for Codeforces.
Recently, Codeforces turned 14 years old. Not bad, right? And for many years now, when asked "What is Codeforces?" the first thing I say is — it's a community!
[cut]<br/>
#### Personal Thanks!
On behalf of the community (and myself), I say thank you to everyone who tries, helps, and makes efforts to keep the community alive.
Thank you to the developers! Although I continue to engage in development and other technical activities, I'm glad that these guys made an effort and improved the platform: [user:geranazavr555,2024-02-04], [user:unreal.eugene,2024-02-04], [user:vbandurin,2024-02-04], [user:ChurakovaAlexandra,2024-02-04], [user:medvezhonokok,2024-02-04]...
Hello, Codeforces. Let's recall 2023, shall we? In this post, I want to
summarize this year
19.
CodeTON Round 5 (Div. 1 + Div. 2, Rated, Prizes!) **Note the unusual start time of the round.**
Hello, Codeforces!
Now that Gaokao is over, we are very glad to invite you to participate in [contest:1842], which will start at [contest_time:1842]. You will be given **9 problems** and **3 hours** to solve them. The round will be rated for everyone.
All problems are written and prepared by [user:Gary2005,2023-06-21], [user:Asuka,2023-06-21], [user:Crying,2023-06-21], [user:sjcsjcsjc,2023-06-21], [user:MonkeyKing,2023-06-21], [user:DerekFeng,2023-06-21], [user:KbltQaQ,2023-06-21], [user:ShmilyTY,2023-06-21] and me.
Statements and editorials will be available in Chinese (Simplified) after the contest.
We would like to give our sincere thanks to:
- [user:errorgorn,2023-06-21] for his wonderful coordination!
- [user:Alexdat2000,2023-06-21] for translating problem statements.
- [user:gyh20,2023-06-21], [user:wangziji,2023-06-21], [user:flowerletter,2023-06-21], [user:themoon,2023-06-21], [user:qiuzx,2023-06-21], [user:Gezh...
**Note the unusual start time of the round.** Hello, Codeforces! Now that
Gaokao is over, we
Announcement of CodeTON Round 5 (Div. 1 + Div. 2, Rated, Prizes!)
20.
Codeforces Round #789 Hello, Codeforces! ฅ(*`ω´*)ฅ
We are glad to invite you to take part in [contest:1677] and [contest:1678], which will be held on [contest_time:1677].
The round will be **rated** for all participants from both divisions. Participants in each division will be offered **6** problems and **2** hours to solve them. Both divisions will share 4 problems.
The problems were written and prepared by [user:funer,2022-05-05], [user:dark_light,2022-05-05], [user:FreshP_0325,2022-05-05], [user:Frank_DD,2022-05-05], [user:qsmcgogo,2022-05-05], [user:winterzz1,2022-05-05], [user:Heltion,2022-05-05], [user:TomiokapEace,2022-05-05] and me.
Thank to:
- [user:74TrAkToR,2022-05-05] for excellent coordination of this round! And translating the statements to Russian.
- [user:KAN,2022-05-08] for helping us to review and fix some statements.
- [user:TomiokapEace,2022-05-05] for helping us to translate **all** the statements and tutorials to English.
- [user:Heltion,2022-05-05] for giving...
Hello, Codeforces! ฅ(*`ω´*)ฅ We are glad to invite you to take part in
[contest:1677] and
Announcement of Codeforces Round 789 (Div. 1)
Announcement of Codeforces Round 789 (Div. 2)
21.
Codeforces Round #772 (Div. 2) Hello, Codeforces!
[user:dannyboy20031204,2022-02-18] and I are glad to invite everyone to participate in [contest:1635], which will be held on [contest_time:1635]. **This Round will be rated for participants with rating lower than 2100.** You will have **2 hours** to solve **6 problems**.
We would like to thank:
- [user:74TrAkToR,2022-02-18] for excellent coordination of the round and translating the statements.
- [user:mhq,2022-02-18], [user:generic_placeholder_name,2022-02-18], [user:null_awe,2022-02-18], [user:ptd,2022-02-18], [user:Fysty,2022-02-18], [user:8e7,2022-02-18], [user:yungyao,2022-02-18], [user:Devil,2022-02-18], [user:amano_hina,2022-02-18], [user:Dragonado,2022-02-18], [user:DIvanCode,2022-02-18], [user:voventa,2022-02-18], [user:lox123,2022-02-18], [user:Marslai24,2022-02-18], [user:FHVirus,2022-02-18], [user:saarang,2022-02-18], [user:Olly_Z,2022-02-18], [user:arseny.__.,2022-02-18], [user:Prokhor08,2022-02-18], [user:sam571128,2022-02-18], [user:efimovpau...
Hello, Codeforces! [user:dannyboy20031204,2022-02-18] and I are glad to invite
everyone to
Announcement of Codeforces Round 772 (Div. 2)
22.
Codeforces Round #816 (Div. 2) Thanks a lot!
==================
for Your participation
Hello, Codeforces!
We are glad to invite everyone to participate in [contest:1715], which will be held on [contest_time:1715]. The round will be rated only for the second division. You will have **6 tasks** and **2 hours** to solve them. _We recommend you read all the problems_.
Round is completely set by winter SIS (Summer Informatics School) students. During the camp we did our best to prepare interesting and creative problems. You can check previous rounds prepared by SIS students: [contest:1720], [Codeforces Round #694](https://codeforces.com/contests/1471,1470), [Codeforces Round #612](https://codeforces.com/contests/1286,1287), [Codeforces Round #530](https://codeforces.com/contests/1098,1099)
We are very thankful to
- task authors and developers: Vasilyev [user:Allvik06,2022-08-17] Alexey, Denis [user:Kapt,2022-08-17] Mustafin, Ivan [user:__silaedr__,2022-08-17] Podvorniy, Ilya [user:ilyakrasnovv,2022-08-1...
Thanks a lot! ================== for Your participation Hello, Codeforces! We
are glad to
Announcement of Codeforces Round 816 (Div. 2)
23.
I Reached GM after 5 years Hello Codeforces! I did it! My main goal for 2022 was to reach red and I succeeded in the last contest of the year by getting +1 delta and going from cursed 2399 to 2400! I was very happy but scared to celebrate because I was worried that my rating would go down to 2399 again after the cheater removal. But now it’s 2401, so I think I’m safe now.
Why am I writing this blog? I'm very excited about this achievement, it means a lot to me and I want to share my happiness with Codeforces. Also people ask me in DM quite often about how I got onto this level or who I am in general, so I think it's time to summarize it all into one blog post.
Oh, wait… You don’t even know me, so why should you keep reading this blog post? Let me introduce myself a little first. I’m a high schooler from a small European country where few people do Codeforces. I love competing in OI and MO, I always did. One day, my father found the Codeforces website and suggested that I should start practicing there. At ...
Hello Codeforces! I did it! My main goal for 2022 was to reach red and I
succeeded in the last
24.
Codeforces Round #764 (Div. 3) Hello! [contest:1624] will start at [contest_time:1624]. You will be offered 7-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **7-8 problems** and **2 hours and 15 minutes** to solve them. One of the problems in this round is **interactive**. Don't forget to read the [guide on interactive problems](https://codeforces.com/blog/entry/45307).
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official s...
Hello! [contest:1624] will start at [contest_time:1624]. You will be offered
7-8 problems with
Announcement of Codeforces Round 764 (Div. 3)
25.
Codeforces Round #804 (Div. 2) Hello, Codeforces! Or, as we like to say in Romania: *Noi nu spunem asa ceva, Codeforces!*
We are proud to finally invite you to participate in [Codeforces Round #804](https://codeforces.com/blog/entry/103966), which will start on [Monday, July 4th, 2022, 14:35 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?day=4&month=7&year=2022&hour=17&min=35&sec=0&p1=166) You will be given **5** problems and **2** hours to solve them. We greatly recommend to read all the problems, statements are very short and straight to the point.
In this round, the theme is not Independance Day related. I know, maybe we should've made the theme "Freedom", but we are not Americans and the puns within the problems were already written.
Joining me on the problem setting panel are:
- Setters: Gheorghies [user:Gheal,2022-06-17] Alexandru, Cozma [user:tibinyte,2022-06-17] Tiberiu-Stefan, Voicu [user:cadmiumky,2022-06-17] Mihai Valeriu
- Vip-Testers: [user:Um_nik,2022-06-17], [user:a...
Hello, Codeforces! Or, as we like to say in Romania: *Noi nu spunem asa ceva,
Codeforces!* We
Announcement of Codeforces Round 804 (Div. 2)
26.
Codeforces Round #779 (Div. 2) Xin chào, Codeforces! (Hello, Codeforces!) ٩ (◕‿◕｡) ۶
Me, [user:_FireGhost_,2022-03-25] and [user:Spyofgame,2022-03-25] are glad to invite you to [contest:1658], which will take place on [contest_time:1658]. **The round will be rated for participants with rating lower than 2100.** You will have **2 hours** to solve **6 problems, one of which is divided into two subtasks**.
In this contest, you will meet _Kitagawa Marin_ and her friends _Gojou_, _Juju_ and _Shinju_ from _My Dress-up Darling_! We hope you will find our problems interesting. Good luck to you all! (ﾉ ◕ ヮ ◕) ﾉ *: ･ ﾟ ✧
<img src="https://i.imgur.com/AFmfwXg.png" align="right" />
We sincerely thank the following people for their contributions in the round:
- [user:errorgorn,2022-03-25] for <strike>rejecting 20 problems from <span style="color: #0000FF"><b>SPyofgame</b></span></strike> coordinating the round and [user:KAN,2022-03-25] who guided him in his first coordination.
- [user:Spyofgame,2022-03-25] and ...
Xin chào, Codeforces! (Hello, Codeforces!) ٩ (◕‿◕｡) ۶ Me, [user:_FireGhost_,2022
-03-25] and
Announcement of Codeforces Round 779 (Div. 2)
27.
Pinely Round 1 (Div. 1 + Div. 2) <img align="right" alt="text" src="/predownloaded/1c/91/1c91ed031100f3338aa5f8ed58d0405adb9ff9d7.png" style="height: 500.0px;max-width: 100.0%;max-height: 100.0%;">
Hello, Codeforces!
Members of team EZEC are glad to invite you to participate in **[contest:1761]**, which will start on **[contest_time:1761]**. You will be given **7** problems, **one of which has a subtask**, and **2 hours and 30 minutes** to solve them. The round will be rated for everyone. It is greatly recommended to read all the problems.
There is at least one interactive problem, so please see the [guide of interactive problems](https://codeforces.com/blog/entry/45307) if you are unfamiliar with it.
We would also like to thank:
- Our red sun [user:orzdevinwang,2022-11-19], the youngest TOP10 coder in history, for illuminating our path.
- Our great emperor [user:antontrygubO_o,2022-11-19] for cooperating and coordinating with us to make this round happen. He saved the round by contributing his problem...
.png" style="height: 500.0px;max-width: 100.0%;max-height: 100.0%;"> Hello,
Codeforces! Members
Announcement of Pinely Round 1 (Div. 1 + Div. 2)
28.
Psyho Challenge: Where are your likes? Hello [user:Psyho,2022-12-21], this is Mike. We are happy to help with likes. So, Codeforces?
He waits for your likes here: https://twitter.com/FakePsyho/status/1605570944537280512?t=MV0OksdeUb8FXKApncDZcw&s=19
I believe that 40 facts are too few for us. We need more!
<img style="width:400px;" src="/predownloaded/e6/c8/e6c8915ea59e3b7b87bcf37af704221af1b66c5d.png"/>
Hello [user:Psyho,2022-12-21], this is Mike. We are happy to help with likes.
So, Codeforces?
29.
Codeforces Global Round 24 Hello Codeforces!<img src="/predownloaded/2e/e2/2ee2f0f95f05aae6ca6f47812dae2dc2aabf277b.png" style="width: 200.0px;float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">
On [contest_time:1764] we will host [contest:1764]. **Note the unusual time of the round.**
It is the sixth round of a 2022 series of [Codeforces Global Rounds](https://codeforces.com/blog/entry/65002). The rounds are open and rated for everybody.
The prizes for this round:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The prizes for the 6-round series in 2022:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
Thanks to XTX, which ...
Hello Codeforces!
Announcement of Codeforces Global Round 24
30.
Editorial for Hello 2023 ## [problem:1779A]
Author: [user:n0sk1ll,2022-12-27]
<spoiler summary="Hint">
What happens when $\texttt{L}$ appears after some $\texttt{R}$ in the string?
</spoiler>
<spoiler summary="Solution">
Suppose that there exists an index $i$ such that $s_i = \texttt{R}$ and $s_{i+1} = \texttt{L}$. Lamp $i$ illuminates trophies $i+1,i+2,\ldots n$ and lamp $i+1$ illuminates $1,2,\ldots i$. We can conclude that all trophies are illuminated if $\texttt{L}$ appears right after some $\texttt{R}$. So, strings $\texttt{LLRRLL}, \texttt{LRLRLR}, \texttt{RRRLLL}, \ldots$ do not require any operations to be performed on them, since they represent configurations of lamps in which all trophies are already illuminated.
Now, we consider the case when such $i$ does not exist and think about how we can use the operation **once**. Notice that if $\texttt{R}$ appears right after some $\texttt{L}$, an operation can be used to transform $\texttt{LR}$ into $\texttt{RL}$, and we have concluded before...
Editorial for Hello 2023, Author: [user:n0sk1ll,2022-12-27]
Tutorial of Hello 2023
31.
CodeTON Round 3 (Div. 1 + Div. 2, Rated, Prizes!) Hello, Codeforces! Or, as we like to say in Romania: Nu îmi amintesc să fi adresat întrebări, Codeforces!
I am glad to finally invite you to participate in [contest:1750], which will start on [contest_time:1750]. You will be given **8** problems and **2 hours and 30 minutes** to solve them. It is greatly recommended to read all the problems, **statements are short and straight to the point**.
I would like to thank:
- [user:Artyom123,2022-10-31] for prodigious coordination.
- [user:AquaMoon,2022-10-31], [user:mejiamejia,2022-10-31], [user:ugly2333,2022-11-05], [user:Ecrade_,2022-10-31] for huge help in preparation and authoring one of the tasks.
- [user:errorgorn,2022-10-31] for being a VIP-tester.
- [user:Lemur95,2022-10-31], [user:Gheal,2022-10-31], [user:Perpetually_Purple,2022-10-31], [user:Everule,2022-10-31], [user:IacobTudor,2022-10-31], [user:andrei_boaca,2022-10-31], [user:lucri,2022-10-31], [user:AlperenT,2022-10-31], [user:Kuroni,2022-10-31], [user:pra...
Hello, Codeforces! Or, as we like to say in Romania: Nu îmi amintesc să fi
adresat întrebări
Announcement of CodeTON Round 3 (Div. 1 + Div. 2, Rated, Prizes!)
32.
Codeforces Round #838 (Div. 2) Hello, Codeforces!
[user:amurto,2022-12-13] and I are glad to invite everyone to participate in [contest:1762], which will be held on [contest_time:1762].
This Round will be rated for participants with rating strictly **lower than 2100**. Participants from the first division are also welcomed to take part in the competition but it will be unrated for them.
You will be given **7 problems** and **2 hours and 30 minutes** to solve them. One of the problems will be **interactive**. Make sure to read [this blog](https://codeforces.com/blog/entry/45307) and familiarize yourself with these types of problems before the round!
We would like to thank:
- [user:errorgorn,2022-12-13] for amazing coordination and help with the problem preparation.
- [user:KAN,2022-12-13] for translation of the statements into Russian
- [user:TheScrasse,2022-12-13] for providing suggestions which helped us to improve one problem.
- [user:GoatTamer,2022-12-13] for discussing problems with us whil...
Hello, Codeforces! [user:amurto,2022-12-13] and I are glad to invite everyone
to participate in
Announcement of Codeforces Round 838 (Div. 2)
33.
Codeforces Round #822 (Div. 2) **UPD: The round has been rescheduled to a different time due to a clash with a CodeChef contest**
Hello CodeForces!
Me, [user:happypotato1207,2022-09-20] and [user:nicholask,2022-09-20] are excited to invite you to participate in [contest:1734]. It will start at [contest_time:1734]. The round will be **rated for everyone with less than 2100 rating**. You have **2 hours** to solve **6 problems**. **Please note the unusual start time**.
We would like to take this opportunity to thank everyone who have contributed to our round:
- [user:darkkcyan,2022-09-17] for his excellent coordination;
- [user:anthony123,2022-09-17] and [user:jerryliuhkg,2022-09-17] for proposing tasks that did not make it to the final problemset;
- [user:thenymphsofdelphi,2022-09-17], [user:kevinxiehk,2022-09-17], [user:xuanquang1999,2022-09-17], [user:ta4p,2022-09-17], [user:ACGN,2022-09-17], [user:Mike4235,2022-09-17], [user:brianlee.lck,2022-09-17], [user:JeffreyLC,2022-09-17], [user:prvocislo,202...
** Hello CodeForces! Me, [user:happypotato1207,2022-09-20] and [user:nicholask,
2022-09-20] are
Announcement of Codeforces Round 822 (Div. 2)
34.
Polynomial Round 2022 (Div. 1 + Div. 2, Rated, Prizes!) Hello, Codeforces!
<img alt="Polynomial" src="https://codeforces.com/predownloaded/31/39/3139af7f9a6628da7d4b7ce4353a192cf59ee3f5.png" style="float:right;height: 250px; margin: 10px; max-width:50%;"/>
Winter holiday is coming! And we are excited to invite you to our third round, [contest:1774], which will be held on [contest_time:1774]. You are given **8 problems** and **2.5 hours** to solve them.
All problems were written and prepared by [user:Ecrade_,2022-12-14], [user:Little09,2022-12-14], [user:ChthollyNotaSeniorious,2022-12-14], [user:DataStructures,2022-12-14], [user:Cirno_9baka,2022-12-14], [user:mejiamejia,2022-12-14] and me.
And thanks to [user:dorijanlendvaj,2022-12-14], [user:gisp_zjz,2022-12-14], [user:gamegame,2022-12-14], [user:triple__a,2022-12-14], [user:Chenyu_Qiu,2022-12-14], [user:Suiseiseki,2022-07-25], [user:q-w-q-w-q,2022-12-14], [user:leukocyte,2022-12-14], [user:waaitg,2022-12-14], [user:Kubic,2022-12-14], [user:LHQing,2022-12-14], [user:zrmpaul...
Polynomial Round 2022 (Div. 1 + Div. 2, Rated, Prizes!), Hello, Codeforces!
Announcement of Polynomial Round 2022 (Div. 1 + Div. 2, Rated, Prizes!)
35.
Codeforces Round #821 (Div. 2) Hello Codeforces!
We invite you to [contest:1733] starting on [contest_time:1733]. The round is **rated for users whose rating is lower than 2100**.
All problems were mainly created and prepared by me. One problem is revised by [user:mejiamejia,2022-09-17]. I would also like to thank:
- [user:MikeMirzayanov,2022-03-01] for Codeforces and Polygon platforms,
- [user:KAN,2022-09-09] for helping preparation of the round,
- [user:Arpa,2022-03-01] for coordinating and reviewing the round,
- [user:mejiamejia, 2022-09-17] for developing one problem and a lot of advices,
- [user:satyam_343,2022-07-09], [user:74TrAkToR,2022-07-12], [user:MagentaCobra,2022-07-27], [user:cadmiumky,2022-08-05], [user:Andreasyan,2022-08-05], [user:darkkcyan,2022-08-06], [user:Vladithur,2022-08-09], [user:Etherite,2022-08-10], [user:welleyth,2022-08-17], [user:mjhmjh1104,2022-08-27], [user:emorgan5289,2022-09-18], [user:jeroenodb,2022-09-18], [user:oolimry,2022-09-18], [user:willy108,2022-09-18], [user:...
Hello Codeforces! We invite you to [contest:1733] starting on
[contest_time:1733]. The round is
Announcement of Codeforces Round 821 (Div. 2)
36.
1st Universal Cup Announcement Hello everyone, we are happy to announce that the 1st Universal Cup is started officially.
Universal Cup is a non-profit organization dedicated to providing training for competitive programming teams. Our website is [https://ucup.ac/](https://ucup.ac/) (in English and Chinese).
In recent years, Chinese problem-setter teams have created a great number of high-quality contests. We have reached an agreement with most of these setters, that they agree to provide contest materials to Universal Cup for hosting mirror contests before publishing the set in public. We believe that such an arrangement can provide good opportunities to teams who want to do better in the future competing.
Every year, with the permission of the problem setter team and without involving copyright disputes, the Universal Cup will hold mirror contests for some undisclosed competition sets. It is expected to hold at least 10 contests a year. We will simulate the actual situation in the competition, using the ...
Hello everyone, we are happy to announce that the 1st Universal Cup is started
officially
37.
Codeforces Round #782 (Div. 2) Hello, Codeforces!
[user:TimeWarp101,2022-04-12] and I are excited to invite you to [contest:1659] which will take place on [contest_time:1659]. **This round will be rated for participants with rating lower than 2100.**
Many thanks to all the people who made this round possible:
- [user:Arpa,2022-04-12] and [user:KAN,2022-04-12] for coordinating the round!
- [user:KAN,2022-04-17] for Russian translations.
- [user:AwakeAnay,2022-04-12] for a lot of advice throughout the process + listening to my terrible problem ideas, and for proposing tasks that did not make it to the final problemset.
- [user:TimeWarp101,2022-04-12] cause I love you uwu <3
- [user:i_am_completely_useless,2022-04-12] for being completely useless.
- [user:antontrygubO_o,2022-04-12], [user:AmShz,2022-04-12], [user:AwakeAnay,2022-04-12], [user:generic_placeholder_name,2022-04-12], [user:TeaTime,2022-04-12], [user:fishy15,2022-04-12], [user:TheScrasse,2022-04-12], [user:kartikeyasri23,2022-04-12], [user:Mage...
Hello, Codeforces! [user:TimeWarp101,2022-04-12] and I are excited to invite
you to [contest
Announcement of Codeforces Round 782 (Div. 2)
38.
Polygon Updates (February 2022) Hello, Codeforces.
In this post, I'll share with you a few recent improvements in Polygon made by [user:MikeMirzayanov,2022-03-03], [user:unreal.eugene,2022-03-03], [user:dk318,2022-03-03] and me.
Polygon is a service to prepares programming problems and contests. It is usually used to prepare problems for olympiads/programming contests but it is also often used to prepare educational content. It is located at https://polygon.codeforces.com/ and is open to everybody.
Here are three recent new features:
* IOI-like Graders for Python
* Problem Materials
* User Groups
[cut]
<br/>
<br/>
IOI-like Graders for Python
==================
About 3 years ago we announced support of IOI graders for C++ in Polygon (Please read [the old post](https://codeforces.com/blog/entry/66916)). Now we have added support for graders written in Python. However, since there is no concept of linkage in Python, Python graders are different from C++ ones.
In the case of Python, the gra...
Polygon Updates (February 2022), Hello, Codeforces.
39.
Codeforces Round #771 (Div. 2) Hello, Codeforces!
I am happy to invite you to [contest:1638], which will take place on [contest_time:1638]. **The round will be rated for participants with rating lower than 2100.** You will have **2 hours** to solve **6 problems**. The problems were authored and prepared by me.
I would like to thank the following people who made the round possible:
- [user:Artyom123,2022-02-13] for coordination, help in problem preparation and translating the statements.
- [user:KAN,2022-02-13] for helping with round preparation.
- [user:geniucos,2022-02-13] and [user:spatarel,2022-02-13] for discussing problems with me way before the round was proposed.
- [user:gamegame,2022-02-13], [user:Kirill22,2022-02-13], [user:AlexLuchianov,2022-02-13], [user:Monogon,2022-02-13], [user:wxhtzdy,2022-02-13], [user:generic_placeholder_name,2022-02-13], [user:BlueDiamond,2022-02-13], [user:Devil,2022-02-13], [user:Ziware,2022-02-13], [user:Utkarsh.25dec,2022-02-13], [user:TeaTime,2022-02-13], [user:...
Hello, Codeforces! I am happy to invite you to [contest:1638], which will take
place on
Announcement of Codeforces Round 771 (Div. 2)
40.
Codeforces Round #784 (Div. 4) Hello Codeforces!
[user:SlavicG,2022-04-19], [user:flamestorm,2022-04-19], [user:MikeMirzayanov,2022-04-19], [user:Errichto,2022-04-19], and I want to invite you to the long-awaited second Div. 4 round!
It starts on [contest_time:1669].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the off...
Hello Codeforces! [user:SlavicG,2022-04-19], [user:flamestorm,2022-04-19],
[user:MikeMirzayanov
Announcement of Codeforces Round 784 (Div. 4)
41.
Codeforces Round #825 (Div. 2) Hello, Codeforces!
[user:lackadaisical_lad,2022-10-07], [user:naman1601,2022-10-07] and I are glad to invite everyone to participate in [contest:1736], which will be held on [contest_time:1736].
This Round will be rated for participants with rating lower than **2100**.
You will be given **5 problems with one subtask** and **2 hours** to solve them
We would like to thank:
- [user:Arpa,2022-10-07] for coordinating the round.
- [user:KAN,2022-10-07] for help in preparation of the round.
- [user:Everule,2022-10-07] for proposing a task that did not make it to the final problemset.
- [user:BucketPotato,2022-10-07], [user:PurpleCrayon,2022-10-07], [user:the_hyp0cr1t3,2022-10-07], [user:welleyth,2022-10-07], [user:MagentaCobra,2022-10-07], [user:recurring_raj,2022-10-07], [user:GoatTamer,2022-10-07], [user:udhavvarma03,2022-10-07], [user:74TrAkToR,2022-10-07], [user:AwakeAnay,2022-10-07], [user:cadmiumky,2022-10-07], [user:TheScrasse,2022-10-07], [user:kal013,2022-10-07]...
Hello, Codeforces! [user:lackadaisical_lad,2022-10-07],
[user:naman1601,2022-10-07] and I are
Announcement of Codeforces Round 825 (Div. 2)
42.
Standard problems have been abused to oblivion and there is little interesting stuff to still be found in them Hi! Sorry for this rather click-baity title, but if you're reading this, you likely care about making Codeforces better. And so do I! And so, I've made a survey...
Motivation
------------------
Some of the recent rounds, especially Div1 have been rather poorly received. Technocup and ByteDance rounds have been downvoted like hell, other rounds don't have particularly impressive contribution either. GR18 also has received a lot of criticism and as far as I remember had more upvotes before its start due to [user:PurpleCrayon,2021-12-28]'s incredibly wholesome announcement. There seems to be something wrong; people rarely compliment the writers for the bits they enjoyed which seems to draw an overall picture of rather unhappy audience.
So, what's wrong exactly?
------------------
Well, I know what I don't like, but it of course may differ for you. For me, the spirit animal of modern competitive progr...
statistically significant. After Hello 2022 I will close the survey, analyze
the answers and probably, . After Hello 2022 I will close the survey, analyze the answers and probably
compile a summary blog. If, The survey closes tomorrow after Hello 2022, if you're willing to contribute
and forgotten, now is
43.
[Suggestion] Faster statement loading at the start of the contest #### Hello codeforces,
The past two rounds (Goodbye 2022, Hello 2023) had quite a lot of participants, which is great, but comes with the downside of a very long loading time for the website at the beginning of the contest, reaching **5 minutes** in "Hello 2023" for me personally.
This kind of delay is annoying in general, but especially during the critical first few minutes of the contest where wasting time on problem A is costly.
Now, the obvious solution would be adding additional resources to the server during peak times, but there's only one<strong style="color:red;">*</strong> big burst of requests and submissions and it cools down pretty fast, so in any case a method to move some of the load on the server to a different time would be very helpful.
My suggestion is publishing the problemset in advance, even 30 minutes before the start, *encrypted*. Then, at the start of the contest the encryption key would be broadcasted to everyone, letting them decrypt the relatively ...
#### Hello codeforces, The past two rounds (Goodbye 2022, Hello 2023) had quite
a lot of
44.
What if tourist goes rainboy mode? (Simulation) DISCLAIMER: NO TOURISTS AND RAINBOYS WERE PINGED
Ah yes, two names that most people on Codeforces have heard -- <b>t<span style="color:red;">ourist</span></b> and <b><span style="color:purple;">rainboy</span></b>, one known as the CP Legend, and one as the user who does everything reverse. Such a great idea to put them together — a hypothetical user with the same ability as <b>t<span style="color:red;">ourist</span></b>, and solves problems the <b><span style="color:purple;">rainboy</span></b> way.
_For those unaware of the "rainboy way", it means solving the problems in reverse order. In particular, if he cannot solve the final problem, he solves no problems in the contest._
Unfortunately, <b><span style="color:purple;">rainboy</span></b> had not yet reached red, peaking at 2398 rating. How far can this user go? We shall simulate this user through all the contests that tourist and rainboy took part in comparably, which adds up to 60 contests from [contest:745] to [cont...
58Hello 2022 <>Jan/03 <>
45.
April Fools Day Contest 2024 Hello, <s>April Fools lovers</s> Codeforces!
We, [user:AlperenT,2024-03-26], [user:flamestorm,2024-03-26], [user:toxicpie9,2024-03-26], and [user:willy108,2024-03-26], would like to invite everyone on Codeforces to [contest:1952]! The 12th April Fools Day Contest will take place on [contest_time:1952]. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.
In this round, you will be given $n$ cool bugaboos where $-1 \le n \le \textbf{[REDACTED]}$ and **2** hours to solve them. The contest will use extended ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces, unless the problem says otherwise.
Please note that the round is **unrated** and that the penalty for a **wrong submission** is **10** minutes.
To get an idea of what the contest will look like, you can check out the contests of the pas...
Hello, April Fools lovers Codeforces! We, [user:AlperenT,2024-03-26],
[user:flamestorm
Announcement of April Fools Day Contest 2024
46.
[Gym] Heltion Contest 1 Hello everyone, this is my first contest, and now it is loaded on the [gym](https://codeforces.com/gym/103914).
It was used as [2022 Nowcoder Summer Camp, Day 8](https://ac.nowcoder.com/acm/contest/33193) and [2022 Petrozavodsk Summer Camp, Day 6](https://official.contest.yandex.com/ptz-summer-2022/contest/39551).
All problems are prepared by me. Thanks
- [user:jiangly,2022-09-11] for the idea of the problem C;
- [user:lzr_010506,2022-09-11] for reviewing the problems;
- [user:Suika_predator,2022-09-11] for the solution of the problem L;
- [user:Gassa,2022-09-11] for fixing the statements of the problems;
- [user:MikeMirzayanov,2022-09-11] for Codeforces and Polygon;
- and all testers including [user:1zhuxiaobaicai,2022-09-11], [user:20203246,2022-09-11], [user:20km_shimakaze,2022-09-11], [user:All_Forward,2022-09-11], [user:AyoAyowei,2022-09-11], [user:Bruce12138,2022-09-11], [user:BruceW_07,2022-09-11], [user:Bsqaq,2022-09-11], [user:Cavalier.,2022-09-11], [use...
Hello everyone, this is my first contest, and now it is loaded on the
[gym](https://codeforces.com
Discussion of Heltion Contest 1
47.
Codeforces Round #785 (Div. 2) Hello Codeforces,
I invite you to participate in [contest:1673] which will be held on [contest_time:1673]. **The round will be rated for participants of Division 2 with rating strictly less than 2100**. But as always, the participants of Division 1 are welcome to take part out of competition.
You will be given **6 problems** and **2 hours** to solve them. Moreover, there will be atleast $1$ and atmost $1048576$ interactive problems. So, you are advised to refer to the [guide on interactive problems](https://codeforces.com/blog/entry/45307) in case you are not familiar with them.
I would like to thank the following people for their contribution to the round:
- [user:Artyom123,2022-04-28] for his amazing coordination, helping me throughout the preparation of the round and translating the statements.
- [user:Um_nik,2022-04-28], [user:Monogon,2022-04-28], [user:kclee2172,2022-04-28], [user:TheScrasse,2022-04-28], [user:yash_daga,2022-04-28], [user:Sad_reacts_only,2022-04-28], ...
Hello Codeforces, I invite you to participate in [contest:1673] which will be
held on
Announcement of Codeforces Round 785 (Div. 2)
48.
TeamsCode Summer 2022 Contest **Update: The problems are now uploaded on the gym! Thanks to everyone who participated on our contest! [https://codeforces.com/gym/103870](https://codeforces.com/gym/103870)**
Hello Codeforces! [TeamsCode](https://www.teamscode.org/) is excited to announce the [TeamsCode Summer 2022 Virtual Programming Contest](https://www.teamscode.org/contests/summer-2022)! It will take place on [August 6th, 2022 at 9:45 AM PST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=TeamsCode+Summer+2022+Programming+Contest&iso=20220806T0945&p1=224).
**Teams of up to 4 members will have 3 hours to solve around 10 problems**. There are three divisions: Novice, Intermediate, and Advanced, so no matter what skill level you are, there is a place for you.
Additionally, we will be featuring Dr. Peter Washington, who will be speaking about **Data Science for Digital Behavioral Phenotyping**. Dr. Peter Washington is an Assistant Professor in Information and Computer Sciences at the University ...
TeamsCode Summer 2022 Contest, contest!
[https://codeforces.com/gym/103870](https://codeforces.com/gym/103870)**Hello
Codeforces, Hello Codeforces! [TeamsCode](https://www.teamscode.org/) is excited to
announce the [TeamsCode
49.
Every Technique and Algorithm I Used to Become Grandmaster Hi everyone, I became grandmaster today so I decided to go down memory lane and review every problem I have ever done in a CodeForces contest to look back and see every technique and algorithm I had to use to become a grandmaster. I am not sure how useful this is, I mostly think it's fun to look at all the old solutions I wrote and how different it was from how I write code now. The main takeaway is that, as many people have said before, you don't need to know or memorize a bunch of advanced algorithms to become grandmaster. As you will see, there are many problems where I just used "ad hoc reasoning," meaning there's not a standard technique I used to solve the problem and you just need to make some clever mathematical observations to solve the problem. Also, there are many popular algorithms that I have never needed in a CodeForces contest despite being a grandmaster:
- Sparse tables, Fenwick trees, and segment trees
- String algos, like rolling hashes, Knuth-Morris-Pratt, suffix...
[Hello 2022](https://codeforces.com/contest/1621): Rating went from 2132 to
2085 (-47)
50.
Codeforces Round #799 (Div. 4) Hello Codeforces!
[user:mesanu,2022-06-12], [user:flamestorm,2022-06-12], [user:MikeMirzayanov,2022-06-12] and I want to invite you to [contest:1692]! It starts on [contest_time:1692].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants of th...
Hello Codeforces! [user:mesanu,2022-06-12], [user:flamestorm,2022-06-12],
[user:MikeMirzayanov
Announcement of Codeforces Round 799 (Div. 4)
51.
CodeTON Round 1 (Div. 1 + Div. 2, Rated, Prizes!) Hello!
It is a pleasure to invite you to [contest:1656]! The round will take place on [contest_time:1656]. The round will be **rated** for all participants. The problems of the round were authored by [user:FelixMP,2022-03-20], and they were prepared by [user:FelixMP,2022-03-20] and [user:xpov1LL,2022-03-20].
I would like to thank the following people:
- [user:Baqtraqking,2022-03-20] for having the idea of preparing a Codeforces Round and helping with the solution to one problem; [user:Baqtraqking,2022-03-20], [user:izanbf,2022-03-20] and [user:xpov1LL,2022-03-20] for early help and discussion of problems, and [user:Baqtraqking,2022-03-20], [user:xpov1LL,2022-03-20] and [user:OneStone,2022-03-20] for proposals that did not make it to the final problem set.
- [user:74TrAkToR,2022-03-20] for coordination of the round.
- [user:MikeMirzayanov,2022-03-20] for the great platforms Codeforces and Polygon.
- [user:Um_nik,2022-03-20], [user:Monogon,2022-03-24], [user:AlexLuchianov...
Hello! It is a pleasure to invite you to [contest:1656]! The round will take
place on
Announcement of CodeTON Round 1 (Div. 1 + Div. 2, Rated, Prizes!)
52.
Codeforces Round #808 Hello, Codeforces!
[user:Imakf,2022-07-15] and I are glad to invite you to [Codeforces Round #808 (Div. 1)](https://codeforces.com/contest/1707) and [Codeforces Round #808 (Div. 2)](https://codeforces.com/contest/1708), which will take place on [contest_time:1707]. In both divisions, you will be given **6 problems** and **2 hours** to solve them all.
We would like to thank:
- [user:Monogon,2022-07-15] for his **1-year** cute coordination and very helpful discussion.
- [user:KAN,2022-07-15] for the great help with round preparation.
- [user:Wolam,2022-07-15] for his discussing the problems with us, which helps us to find the solution.
- [user:smg23333,2022-07-15] for donating his csgo time to test the problems in advance.
- [user:AliShahali1382,2022-07-15], [user:SecondThread,2022-07-15], [user:wxhtzdy,2022-07-15], [user:taran_1407,2022-07-15], [user:Retired_cherry,2022-07-15], [user:antontrygubO_o,2022-07-15], [user:Tlatoani,2022-07-15], [user:errorgorn,2022-07-15], [user:...
Hello, Codeforces! [user:Imakf,2022-07-15] and I are glad to invite you to
[Codeforces Round
Announcement of Codeforces Round 808 (Div. 1)
Announcement of Codeforces Round 808 (Div. 2)
53.
Codeforces Round #791 (Div. 2) Hello, Codeforces!
I'm glad to invite you to Round 791 which will start at [contest_time:1679]. **Please notice the unusual time.**
There will be 6 problems in the round. Round is based on Team Olympiad in Lipetsk which is being held for the seventh time. Problems were proposed and prepared by [user:iakovlev.zakhar,2022-05-12], [user:Kon567889,2022-05-12], [user:iura,2022-05-12], [user:andr1y,2022-05-12], [user:Masha237,2022-05-12], [user:welleyth,2022-05-12] and me. I would like to thank [user:Aleks5d,2022-05-12] and [user:KAN,2022-05-12] for CF round coordination and testers: [user:Um_nik,2022-05-12], [user:353cerega,2022-05-12], [user:errorgorn,2022-05-13], [user:Stepavly,2022-05-12], [user:divanik,2022-05-12], [user:nnv-nick,2022-05-12], [user:4qqqq,2022-05-12], to be continued...
Of course, I'd like to thank all Codeforces team for Codeforces and Polygon beautiful platforms!
I also would like to thank [user:golikovnik,2022-05-12], [user:egneeS,2022-05-12], [user:dshind...
Hello, Codeforces! I'm glad to invite you to Round 791 which will start at
[contest_time:1679
Announcement of Codeforces Round 791 (Div. 2)
54.
Codeforces Round #830 (Div. 2) Hello, Codeforces!
I am happy to invite you to my [contest:1732] which will be held at [contest_time:1732]. <b>The round will be rated for all the participants with rating strictly less than 2100 before </b> [contest_time:1753].
The tasks were created and prepared by [user:74TrAkToR,2020-10-20]. I would like to thank everyone who helped me a lot with round preparation.
<ul style="list-style-type:square">
<li>Coordinator [user:Artyom123,2022-10-20] for excellent communication and help with preparation.</li>
<li>Testers [user:gisp_zjz,2022-10-20], [user:Pointy,2022-10-20], [user:q-w-q-w-q,2022-10-20], [user:feecIe6418,2022-10-20], [user:nnv-nick,2022-10-20], [user:xiaoziya,2022-10-20], [user:Ormlis,2022-10-20], [user:huangzirui,2022-10-20], [user:Chenyu_Qiu,2022-10-20], [user:triple__a,2022-10-20], [user:gyh20,2022-10-20], [user:low_,2022-10-20], [user:voventa,2022-10-20], [user:tibinyte,2022-10-20], [user:Mr.Robot_28,2022-10-20], [user:Qingyu,2022-10-20], [user:RUSH_D_CAT,20...
Hello, Codeforces! I am happy to invite you to my [contest:1732] which will be
held at
Announcement of Codeforces Round 830 (Div. 2)
55.
Educational Codeforces Round 142 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1792] [contest:1792] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2023-01-23] Dalabaev, Vladimir [user:vovuh,2023-01-23] Petrov, Ivan [user:BledDest,2023-01-23] Androsov, Ma...
world with the 8 days intensive Hello Muscat 2023. It will take place in
Muscat, Oman and online from, !_ _Полным ходом идет подготовка ко второму буткемпу по программированию «Hello
Muscat 2023, Hello Codeforces! On [contest_time:1792] [contest:1792] will start. Series of
Educational
Announcement of Educational Codeforces Round 142 (Rated for Div. 2)
56.
Invitation to TOKI Indonesian NOI Open Contest 2022 Hello Codeforces community,
We are excited to invite you to **TOKI Indonesian NOI Open Contest 2022** — an online mirror contest for the Indonesian National Olympiad in Informatics. This national olympiad is one of the stages required for our students to qualify to represent Indonesia in the International Olympiad in Informatics (IOI). You may have seen our past open olympiads ([2015](https://codeforces.com/blog/entry/17924), [2016](https://codeforces.com/blog/entry/44892), [2017](https://codeforces.com/blog/entry/53037), [2018](https://codeforces.com/blog/entry/60263), [2019](https://codeforces.com/blog/entry/67967), [2020](https://codeforces.com/blog/entry/83514), [2021](https://codeforces.com/blog/entry/96689)), and you can check our past problems [here](https://tlx.toki.id/problems/problemsets?archive=osn).
The contest is similar to IOI: 2 competition days (+ 1 trial session), each consisting of 3 IOI-style (partial, subtasks) problems to be solved in 5 hours. The schedule is...
Invitation to TOKI Indonesian NOI Open Contest 2022, Hello Codeforces community,
57.
EGOI 2022 Results and Solutions Hello Codeforces, especially girls!
The second Europian Girls Olympiad of Informatics just finished. The competition was hosted by Turkey in Antalya. It was the first year this competition was held onsite. EGOI is somehow a girls' version of IOI because countries like Singapore and Peru participate in it too. 45 countries participated in EGOI 2022, while the number of countries participating in IOI is ~90.
I was part of the [scientific committee](https://ubilo.tubitak.gov.tr/egoi2022/scientific-committee) of the competition. I found a great team around me.
<center>
<br>
<img width="50%" src="/predownloaded/bf/7a/bf7a40910db18db3ab0a12d0ad3e762f6cb9366c.jpg">
<br>
</center>
From left to right: Fatma Basak Aydemir (Turkey, SC), Nils (Sweden, Problem Setter), Hakan (Turkey, SC), Cheng (China, Problem Setter), I (Iran, SC), Stanislaw (Poland, Problem Setter), Vlad (Romania, SC), Petr (Switzerland, Problem Setter). Tolga Can didn't attend on-site but he was the head scientif...
EGOI 2022 Results and Solutions, Hello Codeforces, especially girls!
Announcement of European Girls Olympiad in Informatics 2022. Day 1
Announcement of European Girls Olympiad in Informatics 2022. Day 2
58.
Codeforces Round #814 ### Hello, Codeforces!
[user:SomethingNew,2022-08-13] and I are glad to invite you to [contest:1718] and [contest:1719], which will take place on [contest_time:1718]. Each division will have 6 problems and 2 hours to solve them.
We would like to thank:
- [user:74TrAkToR,2022-08-14] for excellent coordination and for the idea of a problem for Div. 2.
- [user:pakhomovee,2022-08-14] for idea and preparation of one of the problems for Div. 1, and for testing other problems of the contest.
- [user:Um_nik,2022-08-14], [user:mhq,2022-08-14], [user:turmax,2022-08-14], [user:fedoseev.timofey,2022-08-14], [user:errorgorn,2022-08-14], [user:FairyWinx,2022-08-14], [user:Allvik06,2022-08-14], [user:arbuzick,2022-08-14], [user:AlesyaIvanova,2022-08-14], [user:Dart-Xeyter,2022-08-14], [user:Alexdat2000,2022-08-14], [user:Vladithur,2022-08-14], [user:rafaelka,2022-08-14], [user:lox123,2022-08-14], [user:LeoRiether,2022-08-14], [user:satyam_343,2022-08-14], [user:ilya.kligunov,2022-08-14], [us...
### Hello, Codeforces! [user:SomethingNew,2022-08-13] and I are glad to invite
you to [contest
Announcement of Codeforces Round 814 (Div. 1)
Announcement of Codeforces Round 814 (Div. 2)
59.
Codeforces Round #807 (Div. 2) Hello Codeforces,
We are glad to invite you to [contest:1705], which will be held on [contest_time:1705]. As usual, the round will be rated for participants with ratings lower than 2100, while those who have higher ratings are encouraged to participate unofficially. **Please note the unusual start time.**
You will be given **6 problems** to be solved in **2 hours and 15 minutes**. There may or may not be interactive problems, so you are encouraged to prepare in case they do appear by reading [this guide](https://codeforces.com/blog/entry/45307).
The round is authored by [user:abc241,2022-07-12] and me, while joining us is also [user:inwbearX,2022-07-12] who contributed significantly to the preparation. This is our first time setting rounds in Codeforces, and it wouldn't be possible if there were no support from the following people.
- [user:errorgorn,2022-07-12] for fantastic coordination.
- [user:KAN,2022-07-12], [user:lackadaisical_lad,2022-07-15], [user:geranazavr555,20...
Hello Codeforces, We are glad to invite you to [contest:1705], which will be
held on
Announcement of Codeforces Round 807 (Div. 2)
60.
Infoleague Spring Round 2022 Announcement Hello Codeforces!
We would like to invite you to the first (and possibly only) round of Infoleague Spring 2022, the contest starting on Wednesday, March 30th from [12:30 GMT+3](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Infoleague+Spring+2022+Official+Round&iso=20220330T123030&p1=2209&ah=4). The problems in this round have been prepared to train high school students for the upcoming Romanian National Olympiad in Informatics (ONI).
**The registration period for this contest starts from [6:30 GMT+3](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Infoleague+Spring+2022+Official+Round+Registration&iso=20220330T0630&p1=2209&ah=6) on Wednesday, March 30th**.
This contest has two divisions, Div 1 and Div 2. The Div 2 contest intends to mimic an ONI problemset for 9th and 10th graders, while Div 1 is mainly focused towards challenging 11th and 12th graders.
Contest links: [Div1](https://codeforces.com/gym/103634), [Div2](https://codeforces.com/gym/1036...
Infoleague Spring Round 2022 Announcement, Hello Codeforces!
Announcement of Infoleague Spring 2022 Round Div. 2
Announcement of Infoleague Spring 2022 Round Div. 1
61.
Codeforces Round #820 (Div. 3) Hello! [contest:1729] will start at [contest_time:1729]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them. One of the problems in this round is **interactive**. Don't forget to read the [guide on interactive problems](https://codeforces.com/blog/entry/45307).
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official s...
Hello! [contest:1729] will start at [contest_time:1729]. You will be offered
6-8 problems with
Announcement of Codeforces Round 820 (Div. 3)
62.
Codeforces Global Rounds 2022: Final Results (GR19-GR24) Hello, Codeforces.
It's time to take stock of last year. Shall we begin?
And we are happy to sum up the results of the last season of Global Rounds. We announce the results!
We remind you that the global rounds are a joint initiative of XTX and Codeforces.
We hold 6 such rounds per year. All of them are open to both divisions. At each such round, 50 brand T-shirts were handed out, and we are happy to give T-shirts to all problem authors.
The prizes for the 6-round series are:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
[cut]
The final standings after six rounds (sorted by total points in four best-placed rounds):
| Place | Contestant | = | GR 19 | GR 20 | GR 21 | GR 22 | GR 23 | GR 24|
|--|--|--|--|...
Codeforces Global Rounds 2022: Final Results (GR19-GR24), Hello, Codeforces.
63.
Editorial of SWERC 2021-2022 Online Mirror Hello Codeforces!
Thanks for taking part in the SWERC 2021-2022 mirror. We hope you enjoyed thinking about the problems.
The contest was intended for a wide range of participants. As such, there were "very easy" to "easy" problems (A, M, H) as well as extremely challenging ones (B and J, neither of which appeared in the official contest, together with C). Some problems demanded the knowledge of specific techniques, algorithms or data structures (e.g. E, G, K, J), while others were purely based on insight and deduction (B, D, N).
But without further ado, let's present the editorial!
<br>
## Solutions
---
<br>
<spoiler summary="Solution of Problem A">
[tutorial:1662A]
</spoiler>
Statement by [user:dario2994,2022-04-19], preparation by [user:dario2994,2022-04-19]
<br>
<spoiler summary="Solution of Problem B">
[tutorial:1662B]
</spoiler>
Statement by [user:Giove,2022-04-19], preparation by [user:Giove,2022-04-19]
<br>
<spoiler summary="Solution...
Editorial of SWERC 2021-2022 Online Mirror, Hello Codeforces!
64.
JOI Spring Camp 2022 Online Contest Hello, everyone!
[Japanese Olympiad in Informatics (JOI) Spring Camp 2022](https://contests.ioi-jp.org/joi-sp-2022/index-en.html) will be held from March 20 to March 23. There are **4 days** in this contest.
* Day 1: [March 20, 02:00 GMT — March 20, 24:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Japanese+Olympiad+in+Informatics+%28JOI%29+Spring+Camp+2022+Day1&iso=20220320T02&p1=1440&ah=22)
* Day 2: [March 21, 02:00 GMT — March 21, 24:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Japanese+Olympiad+in+Informatics+%28JOI%29+Spring+Camp+2022+Day2&iso=20220321T02&p1=1440&ah=22)
* Day 3: [March 22, 02:00 GMT — March 22, 24:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Japanese+Olympiad+in+Informatics+%28JOI%29+Spring+Camp+2022+Day3&iso=20220322T02&p1=1440&ah=22)
* Day 4: [March 23, 02:00 GMT — March 23, 24:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Japanese+Olympiad+in+Infor...
JOI Spring Camp 2022 Online Contest, Hello, everyone!
65.
Codeforces Round #815 (Div. 2) Hello, Codeforces!
We are proud to finally invite you to participate in [Codeforces Round #815 (Div. 2)](https://codeforces.com/contest/1720), which will start on [contest_time:1720]. You will be given **5** problems, one of which contains a subtask and **2** hours to solve them. We greatly encourage you to read all the problems.
Round is completely set by SIS (Summer Informatics School) students. During the camp our students did their best to prepare interesting and creative problems. You can check previous rounds prepared by SIS students: [Codeforces Round #612](https://codeforces.com/contests/1286,1287), [Codeforces Round #530](https://codeforces.com/contests/1098,1099), [Codeforces Round #694](https://codeforces.com/contests/1471,1470).
People who participated in the creation of the round:
- Problems are authored and prepared by: Kirill [user:kirill.kligunov,2022-08-16] Kligunov, Gleb [user:zer0brain,2022-08-16] Ustimenko, Alexey [user:Allvik06,2022-08-16] Vasi...
Hello, Codeforces! We are proud to finally invite you to participate in
[Codeforces Round #815
Announcement of Codeforces Round 815 (Div. 2)
66.
COMPFEST 14 Preliminary Online Mirror (Unrated, ICPC Rules, Teams Preferred) <img alt="logo" src="/predownloaded/03/5f/035ff83d655937b478f5fe9f351f79ac0781f6d2.png" style="float: right;height: 100.0px;margin: 10.0px;max-width: 100.0%;max-height: 100.0%;">
Hello, **Codeforces**! 🤗
We are happy to invite you to participate in [COMPFEST 14 Preliminary Online Mirror (Unrated, ICPC Rules, Teams Preferred)](https://codeforces.com/contests/1725) on <a class="contest-time" contestid=1725></a>. COMPFEST is a national **ICPC-style contest** for university students in Indonesia.
The problems are written and prepared by [user:Pyqe,2022-09-02], [user:steven.novaryo,2022-09-02], [user:Nyse,2022-09-02], [user:muhammadhasan01,2022-09-02], [user:gansus,2022-09-02], [user:nandonathaniel,2022-09-02], [user:FerdiHS,2022-09-02], [user:TakeMe,2022-09-02], and [user:NeoZap,2022-09-02].
We would also like to thank:
- [user:KAN,2022-09-02] for helping to host the mirror round;
- rama_pang ([user:rama_pang,2022-09-02], [user:zappeko,2022-09-02], [user:Berted,202...
="float: right;height: 100.0px;margin: 10.0px;max-width: 100.0%;max-height:
100.0%;">Hello
67.
Educational Codeforces Round 128 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1680] [contest:1680] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-05-12] Dalabaev, Vladimir [user:vovuh,2022-05-12] Petrov, Ivan [user:BledDest,2022-05-12] Androsov, Mak...
Hello Codeforces! On [contest_time:1680] [contest:1680] will start. Series of
Educational
Announcement of Educational Codeforces Round 128 (Rated for Div. 2)
68.
fix problem ratings pls (the rainboy effect) [The first few paragraphs of this blog, above the first spoiler, are just for story purposes and are irrelevant to the problem statement]
One fateful day, a naive and young version of me from about 5 days ago had a dream. A dream to stop being so terrified of hard problems. A dream to conquer the most challenging stuff that CF ever had to offer. A dream to... ok, enough of that, that's so stupid. Basically, I've been grinding 3500s lately, mostly for fun (and my god, has it been fun).
Two days prior, I found myself solving [1919G](https://codeforces.com/contest/1919/problem/G). That went fine, but after getting it, I noticed that despite G being 3500, it wasn't even the hardest problem in the contest — that honor went to the next problem, [1919H](https://codeforces.com/contest/1919/problem/H) (the subject of this blog), which had **no solves in-contest**. I concluded that I would have to be insane to try that, and moved on to other problems.
Well, yesterday, I decided I...
for F in [Hello 2022](https://codeforces.com/contest/1621). Just
[look](https://codeforces.com
69.
ICPC World Finals: Ecnerwala vs Errichto Kotlin Match Hello, codeforces.
To unveil the full power of Kotlin and JetBrains tools, as well as their advantages in algorithmic problem-solving, we’ve invited two competitive programming stars to match their skills in solving Kotlin problems on stage at the ICPC World Finals.
Andrew ~ecnerwala,2022-11-06 He, one of the top competitive programmers in the world, will compete in a match against Kamil ~Errichto,2022-11-06 Debowski, Codeforces "Legendary Grandmaster" and Topcoder "Target." The match will be commentated by none other than Roman ~elizarov,2022-11-06 Elizarov, Kotlin Lead Language Designer.
You can join the stream on [Kotlin by JetBrains youtube channel](https://youtu.be/watch?v=5V0ctpzng34) at [contest_time:1755] and view submissions in the special Codeforces round [contest:1755]. Only ~ecnerwala,2022-11-06 and ~Errichto,2022-11-06 can participate in the round, while you will be able to join as spectators.
We will reuse some problems from previous Div3 rounds. We most...
Hello, codeforces. To unveil the full power of Kotlin and JetBrains tools, as
well as their
Announcement of Ecnerwala vs Errichto Kotlin Match
70.
Educational Codeforces Round 131 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1701] [contest:1701] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-07-07] Dalabaev, Vladimir [user:vovuh,2022-07-07] Petrov, Ivan [user:BledDest,2022-07-07] Androsov, Mak...
Hello Codeforces! On [contest_time:1701] [contest:1701] will start. Series of
Educational
Announcement of Educational Codeforces Round 131 (Rated for Div. 2)
71.
Codeforces Global Round 23 Hello Codeforces!
On [contest_time:1746] we will host [contest:1746]. **<img src="/predownloaded/2e/e2/2ee2f0f95f05aae6ca6f47812dae2dc2aabf277b.png" style="width: 200.0px;float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">**
It is the fifth round of a 2022 series of [Codeforces Global Rounds](https://codeforces.com/blog/entry/65002). The rounds are open and rated for everybody.
The prizes for this round:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The prizes for the 6-round series in 2022:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
- The best 20 participants over all series get sweatshirts and place certificates.
Thanks to XTX, which in 2022 supported the global rounds ...
Hello Codeforces! On [contest_time:1746] we will host [contest:1746]. **
Announcement of Codeforces Global Round 23
72.
Codeforces Round 872 (Div. 1 & 2) Hello Codeforces! （你好，代码部队）
We are glad to invite you to participate in [contest:1824] and [contest:1825] on [contest_time:1824]. **Please note the unusual start time.**
This round is rated for **all the participants**. You will be given 5 problems (one of which is divided into two subtasks) and 2 hours to solve them in each division.
Assume you are [user:YuezhengLing,2023-04-30], and in this round, your best friend [user:luotianyi,2023-04-23] will give you several problems to solve.
([user:luotianyi,2023-04-23] is the left one and [user:yuezhengling,2023-04-30] is the right one)
We would like to thank:
1. [user:RedLycoris,2023-04-22], [user:CrTsIr,2023-04-22], [user:Gyy_cj,2023-04-22], [user:SanweiTreap,2023-04-22] and [user:Gezhiyuan,2023-02-06] for writing the problems.
2. [user:Artyom123,2023-04-22] for coordinating the round.
3. [user:MikeMirzayanov,2023-05-06] for great Codeforces and Pol...
Hello Codeforces! （你好，代码部队） We are glad to invite you to participate in
[contest:1824] and
Announcement of Codeforces Round 872 (Div. 1)
Announcement of Codeforces Round 872 (Div. 2)
73.
Codeforces Round #826 (Div. 3) Hello! [contest:1741] will start at [contest_time:1741]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them.
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _trusted participant of the thi...
Hello! [contest:1741] will start at [contest_time:1741]. You will be offered
6-8 problems with
Announcement of Codeforces Round 826 (Div. 3)
74.
VNOI Cup 2022 Round 1 [Mirror invitation] Hello Codeforces!
<!-- Short sentence for invitation -->
We are glad to invite you to take part in mirror round of [the first round of VNOI Cup](https://oj.vnoi.info/contest/vnoicup22_r1_mirror), which will take place [at 13:00 UTC, on this Saturday, 18th June](https://www.timeanddate.com/worldclock/fixedtime.html?msg=%5BMirror%5D%20VNOI%20Cup%202022%20-%20Round%201&iso=2022-06-18T13:00:00), and it is hosted on our builtin platform — [VNOJ](https://oj.vnoi.info/)!
<center>
<img src="/predownloaded/5a/27/5a27775a5a9c31eea4eb942d31bdd4ade1ef35e7.png" alt="round1-poster" />
</center>
<!-- Ask qualified participants to take part in the official round -->
**If you are Vietnamese and _qualified_ according to these rules mentioned on [this post](https://cup.vnoi.info/rule/)**, please consider taking part in [the official round](https://oj.vnoi.info/contest/vnoicup22_r1)!
<!-- Introduce VNOI -->
VNOI Cup is a Competitive Programming competition held by VNOI (Vietnam Oly...
VNOI Cup 2022 Round 1 [Mirror invitation], Hello Codeforces!
75.
CodeTON Round 7 (Div. 1 + Div. 2, Rated, Prizes!) Hello Codeforces,
We are very glad to invite you to participate in [contest:1896], which will start on [contest_time:1896]. You will be given **8 problems** and **2.5 hours** to solve them. The round will be rated for everyone.
All the problems are written and prepared by [user:lanhf,2023-11-22], [user:Mike4235,2023-11-22], [user:thenymphsofdelphi,2023-11-22], [user:xuanquang1999,2023-11-22] and me.
We would like to give our sincere thanks to:
- [user:errorgorn,2023-11-22] for his wonderful coordination!
- [user:Alexdat2000,2023-11-22] for translating problem statements.
- [user:Um_nik,2023-11-22] and [user:conqueror_of_tourist,2023-11-22] for Legendary Grandmaster testing.
- [user:jeroenodb,2023-11-22], [user:Kuroni,2023-11-22], [user:dario2994,2023-11-22] and [user:dreamoon_love_AA,2023-11-22] for International Grandmaster testing.
- [user:generic_placeholder_name,2023-11-22], [user:MofK,2023-11-22], [user:minhcool,2023-11-22], [user:dvdg6566,2023-11-22] and [user:mag...
Hello Codeforces, We are very glad to invite you to participate in
[contest:1896], which will
Announcement of CodeTON Round 7 (Div. 1 + Div. 2, Rated, Prizes!)
76.
CodeTON Round 4 (Div. 1 + Div. 2, Rated, Prizes!) Hello, Codeforces!
I'm very glad to invite you to participate in [CodeTON Round 4 (Div. 1 + Div. 2, Rated, Prizes!)](https://codeforces.com/contests/1810), which will start on [contest_time:1810].You will be given **8 problems** and **2 hours** to solve them. The round will be rated for everyone.
I'd like to give my sincere thanks to:
* [user:74TrAkToR,2023-03-29] for the wonderful coordination!
* [user:Sulfox,2023-03-29] for the help with the statements.
* [user:Suika_predator,2023-03-29], [user:SSerxhs,2023-03-29], [user:LLL_2820,2023-03-29], [user:xay5421,2023-03-29], [user:NemanjaSo2005,2023-03-29], [user:applese,2023-03-29], [user:bxhnb,2023-03-29], [user:fr200110217102,2023-03-29], [user:Sulfox,2023-03-29], [user:CCSU_DZX,2023-03-29] [user:PaperCloud,2023-03-29], [user:CedeaT0,2023-03-29], [user:Kath1031,2023-03-29], [user:jcccc,2023-03-29], [user:dyxg,2023-03-29], [user:tzc_wk,2023-03-29], [user:xiaoziya,2023-03-29], [user:qiqi20021026,2023-03-29], [user:Pointy,20...
Hello, Codeforces! I'm very glad to invite you to participate in [CodeTON Round
4 (Div. 1 + Div
Announcement of CodeTON Round 4 (Div. 1 + Div. 2, Rated, Prizes!)
77.
Codeforces Round #790 (Div. 4) Hello Codeforces!
[user:SlavicG,2022-05-09], [user:mesanu,2022-05-09], [user:MikeMirzayanov,2022-05-09], [user:Errichto,2022-05-09], and I welcome you to [contest:1676]. It starts on [contest_time:1676].
The format of the event will be the same as before:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted partic...
Hello Codeforces! [user:SlavicG,2022-05-09], [user:mesanu,2022-05-09],
[user:MikeMirzayanov
Announcement of Codeforces Round 790 (Div. 4)
78.
Codeforces Round #827 (Div. 4) Hello Codeforces!
[user:mesanu,2022-06-12], [user:flamestorm,2022-10-11], [user:MikeMirzayanov,2022-06-12] and I are glad to invite you to [contest:1742]! It starts on [contest_time:1742].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants o...
Hello Codeforces! [user:mesanu,2022-06-12], [user:flamestorm,2022-10-11],
[user:MikeMirzayanov
Announcement of Codeforces Round 827 (Div. 4)
79.
Some IOI 2022 Statistics Hello CF! Following IOI 2022, I did some analysis from the scoreboard. Here are my findings.
Country Standings
------------------
This has already been posted on codeforces [here](https://codeforces.com/blog/entry/105957), but mine is slightly different as it uses the total score instead of the average (hence countries with less than 4 participants are ranked higher than the ones with 4 in mine).
Top 5:
| Rank | Country | Average Score |
|---------------|---------------|---------------|
| 1 | CHN | 577.50 |
| 2 | USA | 477.14 |
| 3 | JPN | 467.77 |
| 4 | KOR | 406.11 |
| 5 | CAN | 376.01 |
<spoiler summary="Full Country Standings">
| Rank | Country | Average Score |
|---------------|---------------|---------------|
| 1 | CHN | 577.50 |
| 2 | USA | 477.14 |
| 3 | JPN | 467.77 |
| 4 | KOR | 406.11 |
| 5 | CAN | 376.01 |
| 6 | TWN | 375.51 |
| 7 | UKR | 375.07 |
| 8 | IRN | 361.89 |
| 9 | ROU | 346.69 |
| 10 | IOI | 342.09 |
| 11 | HRV | 336.90 |
| 12 | P...
Some IOI 2022 Statistics, Hello CF! Following IOI 2022, I did some analysis from the scoreboard. Here are
my findings
80.
Codeforces Round #811 (Div. 3) Hello! [contest:1714] will start at [contest_time:1714]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.
You will be given 6-8 problems and 2 hours and 15 minutes to solve them.
Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted parti...
Hello! [contest:1714] will start at [contest_time:1714]. You will be offered
6-8 problems with
Announcement of Codeforces Round 811 (Div. 3)
81.
Help Greek IOI Team Raise Money to Participate On-site in IOI 2022 **TL;DR** The Greek National Informatics team is holding a crowdfunding campaign to become able to participate on-site in IOI 2022 in Indonesia
[Click here to donate](https://gogetfunding.com/help-greek-ioi-team-raise-money-to-participate-on-site-in-ioi-2022/)
Hello dear Codeforces community,
My name is Oleh Naver and I am from Ukraine. Last month my friend posted a blog on Codeforces about a fundraising campaign for
hosting the Ukrainian selections for IOI. First of all, thank you all so much for donating, we are so grateful that we were
finally able to host them. Now my dear friends from Greece who have qualified for IOI and helped in our crowdfunding are facing
an economical issue. Apparently because the spread of the coronavirus has affected the financial state of businesses and
national economies, they can't find sponsors to cover the expenses for them to travel on-site to Indonesia.
Let me highlight the importance of participating in on-site Olympiads ins...
Help Greek IOI Team Raise Money to Participate On-site in IOI 2022, /help-greek-ioi-team-raise-money-to-participate-on-site-in-ioi-2022/) Hello
dear Codeforces community, Hello dear Codeforces community,
82.
TeamsCode Spring 2022 Online Programming Contest Hello Codeforces! [TeamsCode] (https://teamscode.org/) is excited to announce the [**Spring 2022 Online Programming Contest**](https://www.teamscode.org/contests/spring-2022)! The contest will take place on [Saturday, April 2nd, from 9 AM to 5 PM (Pacific Time)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=TeamsCode+Spring+2022+Online+Programming+Contest&iso=20220402T09&p1=137&ah=8). Teams of up to 4 members will have 3 hours to solve ~10 problems. This competition has three divisions: Novice, Intermediate, and Advanced, so no matter what skill level you are in, there is a place for you.
In addition to our algorithmic competition, TeamsCode will be featuring two speakers, Brian Dean, the head of USA Computing Olympiad (USACO), and Jonathan Paulson, an avid competitive programmer and USACO staff member.
Over **4500** dollars worth of prizes will be given out, including placement awards, raffle prizes, and more! Only pre-college participants are eligible for prizes.
...
TeamsCode Spring 2022 Online Programming Contest, Hello Codeforces! [TeamsCode] (https://teamscode.org/) is excited to announce
the [**Spring2022
83.
Codeforces Round #835 (Div. 4) Hello Codeforces!
[user:mesanu,2022-06-12], [user:flamestorm,2022-10-11], [user:MikeMirzayanov,2022-06-12] and I are glad to invite you to [contest:1760]! It starts on [contest_time:1760].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants o...
Hello Codeforces! [user:mesanu,2022-06-12], [user:flamestorm,2022-10-11],
[user:MikeMirzayanov
Announcement of Codeforces Round 835 (Div. 4)
84.
Codeforces Round #776 (Div. 3) Hello! [contest:1650] will start at [contest_time:1650]. You will be offered 7-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.
You will be given 7-8 problems and 2 hours and 15 minutes to solve them.
Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.
Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:
...
Hello! [contest:1650] will start at [contest_time:1650]. You will be offered
7-8 problems with
Announcement of Codeforces Round 776 (Div. 3)
85.
Codeforces Round #797 (Div. 3) Hello! [contest:1690] will start at [contest_time:1690]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.
You will be given 6-8 problems and 2 hours and 15 minutes to solve them.
Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted parti...
Hello! [contest:1690] will start at [contest_time:1690]. You will be offered
6-8 problems with
Announcement of Codeforces Round 797 (Div. 3)
86.
2022-2023 ICPC, NERC, Southern and Volga Russian Regional Contest [Online Mirror, ICPC Rules] Hello Codeforces!
The Southern and Volga Russian Regional Contest was held in Saratov State University on 22nd of November. This contest was used to qualify the teams from Southern Russia and Volga region to the Northern Eurasia Finals.
On [contest_time:1765], we will conduct the online mirror of this contest. It will last for *5 hours* and is best suited for *teams of three people*, although it is not forbidden to participate in teams of smaller/larger size. The mirror will use ICPC rules, the same as the offline contest.
I would like to express my gratitude to all other jury members: [user:awoo,2022-11-23], [user:Neon,2022-11-23], [user:vovuh,2022-11-23], [user:adedalic,2022-11-23], [user:DmitryKlenov,2022-11-23], [user:dmitryme,2022-11-23], [user:DStepanenko,2022-11-23], [user:elena,2022-11-23] and [user:kuviman,2022-11-23]. Also, big thanks to the contest testers: [user:IlyaLos,2022-11-23], [user:Oleg_Smirnov,2022-11-23], [user:I_remember_Olya_ashmelev,2022-11-23], [user:p...
2022-2023 ICPC, NERC, Southern and Volga Russian Regional Contest [Online
Mirror, ICPC Rules], Hello Codeforces!
87.
JOI 2022/2023 Final Round Online Contest Hello, everyone!
[The 22nd Japanese Olympiad in Informatics (JOI 2022/2023) Final Round](https://contests.ioi-jp.org/joi-ho-2023/index-en.html) will be held from [Sunday, February 12th, 10:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+2022/2023+Final+Round&iso=20230212T10&p1=1440) to [Monday, February 13th, 10:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+2022/2023+Final+Round&iso=20230213T10&p1=1440). The contest information is as follows:
* Contest duration: **4 hours** (You can choose start time freely in 24-hour window)
* Number of tasks: **5 tasks**
* Max score for each task: **100 points**
* Style: **IOI-Style** (There may be some partial scores)
* Problem Statement: **Japanese & English**
Note that since the contest ends at [Monday, February 13th, 10:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+2022/2023+Final+Round&iso=20230213T10&p1=1440), if you start the contest after [Monday, February 13th...
JOI 2022/2023 Final Round Online Contest, Hello, everyone!
88.
CerealCodes Summer 2022 Programming Contest 
Hello Codeforces!
CerealCodes is excited to announce our Summer 2022 Programming Contest!
This contest will be held on [August 13-14th](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CerealCodes+Summer+2022&iso=20220813T11&p1=263) on Codeforces (with 4 different start times).
The competition has three divisions: Novice (USACO Bronze-Silver or Div 3), Intermediate (USACO Silver-Gold or Div 2), and Advanced (USACO Gold-Platinum or Div 1).
You can form teams of up to 3 members, and compete to solve ~6 high quality (cereal themed!) problems within 3 hours.
Over $500 in cash (possibly more) will be given out (in the form of Amazon gift cards), as well as other prizes like merchandise and raffle awards!!! Note: only pre-college teams are eligible for cash awards.
Join our [Discord server](https://discord.gg/qve3dBA8Ek) for more info and access to faster communication about our competiti...
CerealCodes Summer 2022 Programming Contest,  Hello
Codeforces, Hello Codeforces!
89.
Codeforces Round #805 (Div. 3) Hello! [contest:1702] will start at [contest_time:1702]. You will be offered 7-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.
You will be given 7-8 problems and 2 hours and 15 minutes to solve them.
Note that **the penalty** for the wrong submission in this round (and the following Div. 3 rounds) is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only _the trusted participants of the third division_ will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _tr...
Hello! [contest:1702] will start at [contest_time:1702]. You will be offered
7-8 problems with
Announcement of Codeforces Round 805 (Div. 3)
90.
Codeforces Round #780 (Div. 3) Hello! [contest:1660] will start at [contest_time:1660]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them.
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _trusted participant of the th...
Hello! [contest:1660] will start at [contest_time:1660]. You will be offered
6-8 problems with
Announcement of Codeforces Round 780 (Div. 3)
91.
Educational Codeforces Round 135 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1728] [contest:1728] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-09-07] Dalabaev, Vladimir [user:vovuh,2022-09-07] Petrov, Ivan [user:BledDest,2022-09-07] Androsov, Mak...
Hello Codeforces! On [contest_time:1728] [contest:1728] will start. Series of
Educational
Announcement of Educational Codeforces Round 135 (Rated for Div. 2)
92.
Educational Codeforces Round 141 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1783] [contest:1783] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2023-01-07] Dalabaev, Vladimir [user:vovuh,2023-01-07] Petrov, Ivan [user:BledDest,2023-01-07] Androsov, Ma...
world with the 8 days intensive Hello Muscat 2023. It will take place in
Muscat, Oman and online from, !_ _Мы рады объявить о втором буткемпе по программированию «Hello Muscat 2023»,
продолжении серии, Hello Codeforces! On [contest_time:1783] [contest:1783] will start. Series of
Educational
Announcement of Educational Codeforces Round 141 (Rated for Div. 2)
93.
[Rated, Prizes!] DYTECHLAB Cup 2022 Round Announcement [Div.1 + Div.2] <img src="/predownloaded/ff/85/ff85322f740c69d9497bd061c096bad892766f13.png" align="right" style="height: 400px;" alt="text"/>
> Hello Codeforces. Hoping you're having a wonderful day! ^_^
# DYTECHLAB Cup 2022
This October, we invite you to the **first ever [contest:1737]** that will start on [contest_time:1737]. The problems were prepared by members of our company who _share a passion for Competitive Programming_. It is an open and rated round for both divisions.
The round will consist of **7 problems** and will be **150 minutes** long. We wish everyone good luck and have a positive delta!
### Prizes
- 1st place: **US$200** cash prize
- 2nd place: **US$100** cash prize
- 3rd place: **US$50** cash prize
Also, we understand that contestants like dope **MERCHANDISE**, so we are giving away lots of them!
- **Top 20** will get a merchandise package which will include: a t-shirt **with your Codeforces handle on it**, a notebook, 2 pens, and a sports bag.
- **3...
[Rated, Prizes!] DYTECHLAB Cup 2022 Round Announcement [Div.1 + Div.2], ="height: 400px;" alt="text"/> > Hello Codeforces. Hoping you're having a
wonderful day, > Hello Codeforces. Hoping you're having a wonderful day! ^_^
Announcement of Dytechlab Cup 2022
94.
Codeforces Round #787 (Div. 3) Hello! [contest:1675] will start at [contest_time:1675]. You will be offered 6-7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.
You will be given 6-7 problems and 2 hours and 15 minutes to solve them.
Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted parti...
Hello! [contest:1675] will start at [contest_time:1675]. You will be offered
6-7 problems with
Announcement of Codeforces Round 787 (Div. 3)
95.
Codeforces Round #850 Hello!
Welcome to [contest:1785] and [contest:1786] that will start on [contest_time:1785]. Both rounds will be rated.
This round is a mirror of VK Cup 2022 Final — annual programming championship for Russian-speaking competitors organized by VK. VK Cup [started in 2012](https://codeforces.com/vkcup2012) and has grown to be a five-track competition in competitive programming, Mobile, ML, Go, and JavaScript.
All the problems of Div. 1 round are authored and prepared by me, while [user:KAN,2023-02-05] authored and prepared two problems for Div. 2. Thanks to [user:errorgorn,2023-02-03], [user:irkstepanov,2023-02-03], [user:qwerty787788,2023-02-05], [user:Merkurev,2023-02-05], [user:IgorI,2023-02-05], [user:PavelKunyavskiy,2023-02-05], [user:izban,2023-02-05], [user:Alexdat2000,2023-02-05], [user:I_Remember_Olya_ashmelev,2023-02-05], [user:Akulyat,2023-02-05], [user:mike_live,2023-02-05], [user:Ekler,2023-02-05], [user:Kalashnikov,2023-02-05] for making this round better.
You w...
Hello! Welcome to [contest:1785] and [contest:1786] that will start on
[contest_time:1785]. Both
Announcement of VK Cup 2022 - Финальный раунд (Engine)
96.
Educational Codeforces Round 123 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1644] [contest:1644] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-02-21] Dalabaev, Vladimir [user:vovuh,2022-02-21] Petrov, Ivan [user:BledDest,2022-02-21] Androsov, Mak...
Hello Codeforces! On [contest_time:1644] [contest:1644] will start. Series of
Educational
Announcement of Educational Codeforces Round 123 (Rated for Div. 2)
97.
VNOI Cup 2022 Final round [Mirror invitation] Hello Codeforces!
After three elimination round, we are glad to announce the [final round of VNOI Cup](https://oj.vnoi.info/contest/vnoicup22_final_mirror), which which will take place at [2:00 UTC on this Friday, 22th July, ](https://www.timeanddate.com/worldclock/fixedtime.html?msg=%5BMirror%5D%20VNOI%20Cup%202022%20-%20Final&iso=2022-07-22T02:00:00), and it is hosted on our builtin platform — [VNOJ](https://oj.vnoi.info/)!
<center>
<img src="/predownloaded/d5/f2/d5f2b5827ae8606949ac2cf87b8dd0257af085f1.png" href="VNOI cup 2022 final banner" />
</center>
Besides the finalists, this mirror round is open for **everyone**!
VNOI Cup is a Competitive Programming competition held by VNOI (Vietnam Olympiads in Informatics community), which is a non-profit organization, by Vietnamese competitive programmers, for Vietnamese competitive programmers. Our aim is to support the growth of competitive programming in Vietnam, and we hope that this competition is one of the things t...
VNOI Cup 2022 Final round [Mirror invitation], Hello Codeforces!
98.
Codeforces Round #786 (Div. 3) Hello!
[contest:1674] will start at [contest_time:1674]. You will be offered 6 or 7 problems (or 8) with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have rating 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks.
You will be given 6 or 7 (or 8) problems and 2 hours to solve them.
Note that **the penalty** for the wrong submission in this round (and the following Div. 3 rounds) is **10 minutes**.
[Remember] (/blog/entry/59228) that only the <i>trusted participants of the third division</i> will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a <i>trusted partici...
Hello! [contest:1674] will start at [contest_time:1674]. You will be offered 6
or 7 problems (or 8
Announcement of Codeforces Round 786 (Div. 3)
99.
ICPC 2022 Online Challenge powered by HUAWEI <img src="/predownloaded/af/22/af228fee1abb015217d8c524de74898aeff36419.png" align="right" style="height: 300px;" alt="text"/>
Hello, Codeforces!
We are happy to invite you to an exciting online event: **ICPC 2022 Online Challenge powered by HUAWEI**，which will start on **[September 15, 2022, 00:00 UTC (UTC+0)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=ICPC+2022+Online+Challenge+powered+by+HUAWEI&iso=20220915T00).**
In this Challenge, you will have a unique chance:
- to compete for **2 weeks online** during the challenge
- to solve **1 or 2 problems** prepared by different business domains of HUAWEI
- to win amazing prizes from HUAWEI!
As a special prize, HUAWEI together with ICPC Foundation will provide the travel trip to the 46th Annual ICPC World Finals in a guest role to the 2 winners (1 winner for each problem)!
**Everyone is welcome to participate. It is an individual competition.**
**ICPC 2022 Online Challenge powered by HUAWEI** (open to t...
ICPC 2022 Online Challenge powered by HUAWEI, Hello, Codeforces!
Announcement of ICPC 2022 Online Challenge powered by HUAWEI - Problem 1
Announcement of ICPC 2022 Online Challenge powered by HUAWEI - Problem 2
100.
Top 50 Voted Blog Posts in 2021 Hi.
Here is the list of top-voted blog posts in 2021. Find something interesting for yourself?
| # | Post | Votes | Author |
| - | - | - | - |
| 1 |<a href="/blog/entry/95106">The Ultimate Topic List (with Resources, Problems and Templates)</a> | 4383 | [user:YouKn0wWho,2022-01-02] |
| 2 |<a href="/blog/entry/96333">Codeforces Round #752</a> | 3156 | [user:YouKn0wWho,2022-01-02] |
| 3 |<a href="/blog/entry/87882">User activity in the profile! [new, Feb. 2021]</a> | 3055 | [user:geranazavr555,2022-01-02] |
| 4 |<a href="/blog/entry/89227">Codeforces Round #712</a> | 2866 | [user:Monogon,2022-01-02] ...
Topic List (with Resources, Problems and Templates) | 4383 | [user:YouKn0wWho,
2022-01-02
101.
Codeforces Round #768 (Div. 1, Div. 2) Hello codeforces!
[user:BrayanD,2022-01-24], [user:dmga44,2022-01-24] and I are glad to invite you to [contest:1630] and [contest:1631] which will be held on [contest_time:1630].
Each division will have **6** problems, and you will have **2** hours to solve them. The round will be rated for both divisions.
We would like to thank:
* [user:Aleks5d,2022-01-24] for his excellent round coordination.
* [user:albertolg101,2022-01-24] and [user:jmrh_1,2022-01-24] for helping in the early stages of the contest.
* [user:I_Remember_Olya_ashmelev,2022-01-24], [user:nweeks,2022-01-24], [user:16204,2022-01-23], [user:windazz,2022-01-24], [user:Ali.kh,2022-01-23], [user:vaaven,2022-01-24], [user:marcOS,2022-01-24], [user:low_,2022-01-24], [user:Riladavin,2022-01-24], [user:TeaTime,2022-01-24], [user:MDario,2022-01-24], [user:aniervs,2022-01-24], [user:Dragonado,2022-01-24], [user:Saborit,2022-01-24], [user:4qqqq,2022-01-23] and [user:saarang,2022-01-24] for testing and providing use...
Hello codeforces! [user:BrayanD,2022-01-24], [user:dmga44,2022-01-24] and I are
glad to invite
Announcement of Codeforces Round 768 (Div. 1)
Announcement of Codeforces Round 768 (Div. 2)
102.
Hello Muscat 2023 **<font color="#625bb7">Hello, Codeforces!</font>**
We are pleased to announce the second “Hello Muscat 2023” ICPC programming bootcamp, the continuation of the “Hello” bootcamp series, organised by **<font color="#625bb7">Harbour.Space University</font>**, in collaboration with **<font color="#625bb7">PhazeRo</font>**, **<font color="#625bb7">Gutech</font>**, **<font color="#625bb7">UK Oman Digital Club</font>**, **<font color="#625bb7">Leagues of Code</font>**, **<font color="#625bb7">Gutech CS Club</font>** and **<font color="#625bb7">Codeforces</font>**!
We are inviting all of you to join us from **<font color="#625bb7">March 8th to March 16th, 2023 in Muscat, Oman for an intense 8 days of programming</font>**! It is not only a great opportunity to train but also a chance to discover a new amazing country. There are many reasons why you must visit Oman at least once in your life, from its great people to its natural beauty and surrounding peace. **March is an especially grea...
Hello Muscat 2023, [user:MikeMirzayanov,2022-12-22], Kamil Debowski [user:Errichto,2022-12-22],
Yahor Dubovik [user:mhq, [user:MikeMirzayanov,2022-12-22], Yahor Dubovik [user:mhq,2022-12-22], Artem
Plotkin [user:Rox,2022-12, **Hello, Codeforces!** We are pleased to announce the second “Hello, , smoothing your road towards the joined World Finals 2022 and 2023 in Egypt!
103.
Codeforces Round #828 (Div. 3) Hello! [contest:1744] will start at [contest_time:1744]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them.
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _trusted participant of the thi...
Hello! [contest:1744] will start at [contest_time:1744]. You will be offered
6-8 problems with
Announcement of Codeforces Round 828 (Div. 3)
104.
Codeforces Round #834 (Div. 3) Hello! [contest:1759] will start at [contest_time:1759]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them.
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _trusted participant of the thi...
Hello! [contest:1759] will start at [contest_time:1759]. You will be offered
6-8 problems with
Announcement of Codeforces Round 834 (Div. 3)
105.
Data Structures in Dynamic Programming Week [](https://youtu.be/Aaceu-Z0abc)
(click on the thumbnail to watch a YouTube video)
Welcome back to what I called "ds in dp week", and you'll see in a second what this is all about. But first I wanted to share some stats with you:
### Contests
This week I took part in 7 contests. Four of them are rated for me, and in the remaining three, I participated unofficially.
I took second place in the Hacker Earth's Easy competition, got on the first standings page of LeetCode Biweekly Contest 69, and had my best TopCoder performance so far, which saw 164 points rating increase.
Codeforces' Hello 2022 didn't go so well, with me managing to solve only A-D. Luckily I only got -15, a surprisingly forgiving rating change for an underperformance.
The remaining three competitions were unrated for me, so I didn't pay much attention to them. It partially explains my questionable results on CodeChef Start...
best TopCoder performance so far, which saw 164 points rating increase.
Codeforces'Hello 2022, solve the most difficult two from the Hello 2022 Codeforces round and a
challenging TopCoder, 1. We'll start off with [problem G from CodeForces' Hello 2022
](https://codeforces.com/contest/1621, Codeforces' Hello 2022 didn't go so well, with me managing to solve only A-D.
Luckily I only got
106.
Codeforces Round #806 (Div. 4) Hello Codeforces!
[user:SlavicG,2022-07-07], [user:flamestorm,2022-07-07], [user:MikeMirzayanov,2022-07-11] and I want to invite you to [contest:1703].
It starts on [contest_time:1703].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants o...
Hello Codeforces! [user:SlavicG,2022-07-07], [user:flamestorm,2022-07-07],
[user:MikeMirzayanov
Announcement of Codeforces Round 806 (Div. 4)
107.
A Recap of My First Year in CodeForces Hello all on Codeforces!
------------------
It’s been just over a full year since I created my Codeforces account. Since then a lot has happened on my Codeforces journey so far. With everything that’s happened I want to look back at how I got to my current point, share what I learned in the process, recap some of my best moments, and laugh at whatever I was thinking on a few of these contests, because a lot happened. The only issue is that there’s no way I’m going to detail all **60** contests I took part in 2022. Instead I’ve chosen to “award” the 9 most memorable contests, wheter it be because I did exceedingly well or self destructed in almost hilarious fashion.
A few notes before I begin: No full solutions for any problems are shown in this post but there are code snippets and discussions that are spoilers for these problems. I apologize in advance.
### First Contest — [Hello 2022](https://codeforces.com/contest/1621)
This was the first contest held in 2022, ...
### First Contest — [Hello 2022](https://codeforces.com/contest/1621)
108.
The 1st Universal Cup. Stage 11: Shanghai (2022 ICPC EC Final) Hello Codeforces! The 11th Stage of the 1st Universal Cup is coming. It will be held from April 8th to 9th. It is also a replay of the 2022 ICPC East Continent Final Contest, which was held on March 24, 2023 — March 26, 2023.
As usual, we have three time windows for participating. You can participate in the contest in the following three time windows:
* [April 8th 13:00 — 18:00 (UTC +8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=The+1st+Universal+Cup.+Stage+11%3A+Shanghai+Time+Window+1&iso=20230408T13&p1=237&ah=5)
* [April 8th 19:00 — 24:00 (UTC +8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=The+1st+Universal+Cup.+Stage+11%3A+Shanghai+Time+Window+2&iso=20230408T19&p1=237&ah=5)
* [April 9th 02:00 — 07:00 (UTC +8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=The+1st+Universal+Cup.+Stage+11%3A+Shanghai+Time+Window+3&iso=20230409T02&p1=237&ah=5)
Please note that you can see two scoreboards in DOMjudge. The 'L...
The 1st Universal Cup. Stage 11: Shanghai (2022 ICPC EC Final), Hello Codeforces! The 11th Stage of the 1st Universal Cup is coming. It will be
held from April 8th
109.
Educational Codeforces Round 139 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1766] [contest:1766] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-12-11] Dalabaev, Vladimir [user:vovuh,2022-12-11] Petrov, Ivan [user:BledDest,2022-12-11] Androsov, Mak...
Hello Codeforces! On [contest_time:1766] [contest:1766] will start. Series of
Educational
Announcement of Educational Codeforces Round 139 (Rated for Div. 2)
110.
April Fools Day Contest 2023 Hello, Codeforces!
I, along with [user:AlperenT,2023-03-30], [user:Ari,2023-03-30], [user:BucketPotato,2023-03-30], [user:ScarletS,2023-03-30], and [user:ToxicPie9,2023-03-30], would like to invite everyone on Codeforces to the [contest:1812]! The 11th April Fools Day Contest will take place on [contest_time:1812]. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is.
Please note that the round is **unrated**.
In this round you'll be given $n$ weird problems and 2 hours to solve them, where $7 \leq n \leq 12$. At most $\sqrt{n}$ of the problems will be [interactive](https://codeforces.com/blog/entry/45307). The contest will use ACM ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them).
You can submit solutions in any language allowed by Codeforces, unless the problem says otherwise. To get an idea of what the contest will look like, you can check out the ...
Hello, Codeforces! I, along with [user:AlperenT,2023-03-30],
[user:Ari,2023-03-30
Announcement of April Fools Day Contest 2023
111.
Codeforces Round #775 (Div.1, Div.2, based on Moscow Open Olympiad in Informatics, rated) Hello!
Right now happens the first tour of the Open Olympiad in Informatics, and tomorrow will be the second one. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Team Olympiad, Moscow Olympiad for Young Students and Metropolises Olympiad (rounds <a href="https://codeforces.com/blog/entry/21185">327</a>, <a href="https://codeforces.com/blog/entry/23309">342</a>, <a href="https://codeforces.com/blog/entry/43615">345</a>, <a href="https://codeforces.com/blog/entry/47769">376</a>, <a href="https://codeforces.com/blog/entry/50613">401</a>, <a href="https://codeforces.com/blog/entry/54350">433</a>, <a href="https://codeforces.com/blog/entry/55201">441</a>, <a href="https://codeforces.com/blog/entry/57981">466</a>, <a href="https://codeforces.com/blog/entry/58229">469</a>, <a href="https://codeforces.com/blog/entry/61638">507</a>, <a href="https://codeforces.com/blog/entry/62440">516</a>, <a href="https://codeforces.com/blog/entry/65433">541</a...
Hello! Right now happens the first tour of the Open Olympiad in Informatics,
and tomorrow will
112.
This goddamn formula Hello, Codeforces! [user:74TrAkToR,2022-07-03] and I were solving problems and have noticed one super interesting fact.
So, check this out. [problem:801E] is a very nice problem we have solved. There is an interesting solution with DP on a DAG.
I won't go into detail, but in the end we had to solve this problem:
You are given an array (a) with n different numbers from 0 to m — 1. You need to create an array (b) (with same length) with (not necessary different) numbers, so if you multiply first i numbers of b and get in by modulo m, you will receive a[i]. It's guaranteed, that we can create such array.
Ok, it's easy to understand, that we must solve some equations like $a \cdot x \equiv b \pmod m $.
How to solve it?
We wrote 2 similar solutions, but we had one similar mistake, but.... we got AC.
I've checked jury solution and.... there is this idea toox.
Well, this solution is based on the following fact. We can get $b \pmod m$ by multiplying $a$ on some $x$ if a...
Hello, Codeforces! [user:74TrAkToR,2022-07-03] and I were solving problems and
have noticed one
113.
VNOI Cup 2022 Round 2 [Mirror invitation] Hello again Codeforces!
<!-- Short sentence for invitation -->
We are glad to invite you to take part in mirror round of [the second round of VNOI Cup](https://oj.vnoi.info/contest/vnoicup22_r2_mirror), which will take place [at 13:00 UTC, on this Saturday, 25th June](https://www.timeanddate.com/worldclock/fixedtime.html?msg=%5BMirror%5D%20VNOI%20Cup%202022%20-%20Round%202&iso=2022-06-25T13:00:00), and it is hosted on our builtin platform — [VNOJ](https://oj.vnoi.info/)!
<center>
<img src="/predownloaded/0c/04/0c04e729c4ba111d2f61cd6aaabd649b844d1887.png" alt="round2-poster" />
</center>
<!-- Ask qualified participants to take part in the official round -->
**If you are Vietnamese and _qualified_ according to these rules mentioned on [this post](https://cup.vnoi.info/rule/)**, please consider taking part in [the official round](https://oj.vnoi.info/contest/vnoicup22_r2)!
<!-- Introduce VNOI -->
VNOI Cup is a Competitive Programming competition held by VNOI (Viet...
VNOI Cup 2022 Round 2 [Mirror invitation], Hello again Codeforces!
114.
Codeforces Round #841 (Div. 2) and Divide By Zero 2022 #### Hello, Codeforces!
[The Programming Club, IIT Indore](https://www.linkedin.com/company/progclub-iiti/mycompany/) is proud to present the **8th edition** of its flagship event, **Divide By Zero** — [Codeforces Round #841 (Div. 2) and Divide By Zero 2022](https://codeforces.com/contest/1731), under the annual code-fest, **Euristica'23**.
You can check some of the previous editions of **Divide By Zero** prepared by us : [Codeforces Round #399 (Div. 1 + Div. 2)](https://codeforces.com/blog/entry/50510), [Codeforces Round #474 (Div. 1 + Div. 2)](https://codeforces.com/blog/entry/58754), [Codeforces Round #714 (Div. 2)](https://codeforces.com/blog/entry/89520).
The contest will take place on [contest_time:1731]. **This round will be rated for all participants with a rating lower than 2100.**
People who had a great contribution to making this round possible:
- Problems were authored by [use...
Codeforces Round #841 (Div. 2) and Divide By Zero 2022, #### Hello, Codeforces!
Announcement of Codeforces Round 841 (Div. 2) and Divide by Zero 2022
115.
GeeksForGeeks Code India Code Finals (Open for all) Hello Codeforces,
I am happy to invite you to the **Final Round** of **GeeksforGeeks's Code India Code**.
We don't want to exclude passionate programmers from enjoying the problem set of the final round. Therefore, the contest will be **open for all** users but **only participants who passed in the Qualification Round** held on 6th March **will be eligible for the rewards**.
**Contest Details:**
- Finals Link: ([Register Here](https://practice.geeksforgeeks.org/contest/gfg-mega-contest-finale?utm_source=CF&utm_medium=CF-inf&utm_campaign=CF-CIC-Finale))
- Time: **Thursday, 10 March 2022**, 7:30 PM to 10:00 PM IST.
- Number of Problems: **7 problems**
- There will be no penalties for wrong submissions.
- Tie Breaker: Time to reach X points. (ie, time of last AC solution)
**Prizes:**
- Rank 1: Macbook Pro + Course voucher worth INR 12,000
- Rank 2: iPad Air + Course voucher worth INR 7,000
- Rank 3: Smart Watch + Course Voucher worth INR 3,000
- Rank 4-25: Table...
Hello Codeforces, I am happy to invite you to the **Final Round** of
**GeeksforGeeks's Code
116.
Educational Codeforces Round 136 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1739] [contest:1739] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-09-28] Dalabaev, Vladimir [user:vovuh,2022-09-28] Petrov, Ivan [user:BledDest,2022-09-28] Androsov, Mak...
Hello Codeforces! On [contest_time:1739] [contest:1739] will start. Series of
Educational
Announcement of Educational Codeforces Round 136 (Rated for Div. 2)
117.
ICPC 2022 Online Challenge powered by HUAWEI: Results <img src="/predownloaded/da/0d/da0d971227243d43cc1c6abf2f3f49b18a465b81.png" align="right" style="height: 200px;margin: 10px 20px 20px;" alt="text"/>
Hello!
We are pleased to announce the completion of the ICPC 2022 Online Challenge powered by HUAWEI and announce the results of the competition.
Thank you very much for your interest in the competition. It was exciting for us to follow the results. It's nice that many participants immersed themselves in the proposed tasks and scored high points.
We hope you enjoyed the challenges. Huawei employees have been working on their preparation for a long time.
We remind all winners that you must have an account at https://icpc.global/ in order to receive a prize. The email for this account must exactly match the one used in your Codeforces account. Please verify that this is indeed the case. The deadline is October 14th.
We are happy to announce the winners.
#### Problem 1 Winners:
* [user:Sung.An,2022-10-06]
* [user:Reb...
ICPC 2022 Online Challenge powered by HUAWEI: Results, Hello!
118.
ICPC World Finals Dhaka — Live Broadcast and Mirror! Hello, Codeforces!
<img alt="ICPC World Finals Dhaka Logo" src="/predownloaded/34/3e/343e3d2ae8f44d7c5225d52db21632db4bec56fe.svg" style="height: 300.0px;max-width: 100.0%;max-height: 100.0%;" align="right">
The ICPC World Finals Dhaka will begin on [November 10, 2022 at 11:00 (UTC+6)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=ICPC+World+Finals+Dhaka&iso=20221110T11&p1=73&ah=5). This is the culmination of the 2020-2021 ICPC season, and we have over 130 teams competing for the title of ICPC champion. Please join us on the live broadcast for the main event of the year in competitive programming; commentators will include [user:ecnerwala,2022-11-09], [user:SecondThread,2022-11-09], [user:Egor,2022-11-09], and more! There will also be a live mirror for you to solve the problems alongside the contestants!
Some useful links:
* [ICPC Homepage](https://icpc.global/)
* [World Finals Homepage](https://worldfinals.icpc.global/)
* [World Finals Schedule](https://docs....
Hello, Codeforces!
119.
JOI Open Contest 2022 Hello everyone!<br />
[JOI Open Contest 2022](https://contests.ioi-jp.org/open-2022/index.html) will be held from [Sunday, July 3, 04:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+Open+Contest+2022&iso=20220703T04&p1=1440) to [Monday, July 4, 04:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+Open+Contest+2022&iso=20220704T04&p1=1440). You can start any time and the duration is basically 5 hours. Note that the duration becomes shorter if you start after [Sunday, July 3, 23:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+Open+Contest+2022&iso=20220703T23&p1=1440), i.e. less than 5 hours before the contest ends.<br />
There will be **3 tasks**, and the maximum score for each task is **100 points**. Since this is an **IOI-style contest**, there may be some subtasks. Each submitted source program must be written **only in C++**. Problem statements will be provided both in Japanese and in English. You can find more de...
JOI Open Contest 2022, Hello everyone!
120.
Codeforces Round #817 (Div. 4) Hello Codeforces!
[user:flamestorm,2022-08-28], [user:MikeMirzayanov,2022-07-11] and I want to invite you to [contest:1722].
It starts on [contest_time:1722].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants of the fourth division_ will...
Hello Codeforces! [user:flamestorm,2022-08-28], [user:MikeMirzayanov,2022
-07-11] and I want to
Announcement of Codeforces Round 817 (Div. 4)
121.
Who wanna take apart in friendly competition? **Hello Guys!**
I think everyone who is on this site in one way or another likes to solve problems! So I would like to offer you a _little competition_ :)
All you need is just to:
1. **Write your goal** you would like to achieve before new year, current rating and the number of solved problems.
1. **Solve many different interesting tasks** and raise your rating in the rounds until the new year!
1. **In the new year**, I will write all the progress of each of the users who participate in a new post, and we can start the new year with new ideas!
(List will be updated)
Participants:
Legendary Grandmasters
[user:Vercingetorix,2022-10-17],
Grandmasters
[user:physics0523,2022-10-17], [user:jjang36524,2022-10-17], [user:dmga44,2022-10-17], [user:Artyom123,2022-10-17], [user:SecondThread,2022-10-17], [user:FairyWinx,2022-10-17],
International Masters
[user:anpoli99,2022-10-17],
Masters
[user:swift-zym,2022-10-17], [user:jucason_xu,202...
**Hello Guys!** I think everyone who is on this site in one way or another
likes to solve
122.
XXII Open Cup. Grand Prix of Seoul Hello!
XXII Open Cup. Grand Prix of Seoul will be held in [2022/07/17 Sunday, 17:00 KST (UTC+9)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=GP+of+Seoul+2022&iso=20220717T17&p1=3999&ah=5).
The contest was used as a Day 2 Contest for ByteDance Summer Camp 2022.
Problems were authored by [user:jh05013,2022-07-12], [user:molamola.,2022-07-12], [user:jihoon,2022-07-12], [user:ainta,2022-07-12], [user:pichulia,2022-07-12], [user:chaeyihwan,2022-07-12], [user:evenharder,2022-07-12], [user:tlewpdus,2022-07-12], [user:applist,2022-07-12], [user:cauchy_function,2022-07-12].
Special thanks to myself for translating the statements and editorials.
Enjoy!
<spoiler summary="List of relevant previous contests">
* [XVIII Open Cup. GP of Korea](https://codeforces.com/blog/entry/57528)
* [KAIST RUN Spring Contest 2018](https://codeforces.com/blog/entry/59625)
* [XIX Open Cup. GP of Korea](https://codeforces.com/blog/entry/62435)
* [XIX Open Cup. GP of Daejeon](...
Hello! XXII Open Cup. Grand Prix of Seoul will be held in [2022/07/17 Sunday,
17:00 KST (UTC+9
Announcement of XXII Open Cup. Grand Prix of Seoul
123.
Codeforces Round #783 (Div. 1, Div. 2) Hello Codeforces!
I am happy to invite you to [contest:1668], and [contest:1667] which will be held on, [contest_time:1668]! This round is rated for both divisions.
I would like to thank the following people who made the round possible:
- [user:Aleks5d,2022-04-14] for coordinating the round!
- [user:Kan,2022-04-14] for reviewing the problems.
- [user:4qqqq,2022-04-14], [user:YashDwivedi,2022-04-14], [user:k_balint,2022-04-14], [user:Riladavin,2022-04-14], [user:Peti,2022-04-14], [user:Akulyat,2022-04-14], [user:kclee2172,2022-04-14], [user:Errorgorn,2022-04-14], [user:dorijanlendvaj,2022-04-14], [user:KAN,2022-04-14], [user:gamegame,2022-04-14] for testing the round and giving valuable feedback.
- [user:MikeMirzayanov,2022-04-14] for great Codeforces and Polygon platforms.
- [NEAR](https://near.org/) for supporting the Codeforces community! Details can be found in [this post](https://codeforces.com/blog/entry/101398).
- You for participating!
In each division there wil...
Hello Codeforces! I am happy to invite you to [contest:1668], and
[contest:1667] which will be
Announcement of Codeforces Round 783 (Div. 1)
Announcement of Codeforces Round 783 (Div. 2)
124.
Egyptian team is likely not going to IOI. Again. Hello Codeforces,
I'm a member of the Egyptian IOI 2022 team, and I'm not sure yet if we are going to IOI. Historically, the Ministry of Communication and Information Technology (MCIT) sponsored the Egyptian team to travel to IOI. However, this year, there is no confirmation from the MCIT's side at all. Our tickets are not booked until now, and MCIT doesn't either confirm or deny that they will sponsor us this year.
Now, there are fewer tickets left, and the cost of traveling increases as we approach IOI. We all have been practicing really hard for IOI for the past few months. Now, there is very little time for us to make alternative plans to participate onsite.
Note that MCIT provides training and sponsors the team every year so we expected more from the MCIT side. AASTMT has supported us with a part of ticket expenses
In an attempt to collect the remaining part, we created a crowdfunding campaign. Please donate [here](https://gogetfunding.com/iiot-fundraising/).
UPD: W...
Hello Codeforces, I'm a member of the Egyptian IOI 2022 team, and I'm not sure
yet if we are
125.
VNOI Cup 2022 Round 3 [Mirror invitation] Yet again, hello Codeforces!
<!-- Short sentence for invitation -->
We are glad to invite you to take part in mirror round of [the third and the last elimination round of VNOI Cup](https://oj.vnoi.info/contest/vnoicup22_r3_mirror), which will take place [at 13:00 UTC, on this Saturday, 2nd July](https://www.timeanddate.com/worldclock/fixedtime.html?msg=%5BMirror%5D%20VNOI%20Cup%202022%20-%20Round%203&iso=2022-07-02T13:00:00), and it is hosted on our builtin platform — [VNOJ](https://oj.vnoi.info/)!
<center>
<img src="/predownloaded/6d/c7/6dc7ed7087ddae4c89d045b3217e37ade2f8445f.png" alt="round3-poster" />
</center>
<!-- Ask qualified participants to take part in the official round -->
**If you are Vietnamese and _qualified_ according to these rules mentioned on [this post](https://cup.vnoi.info/rule/)**, please consider taking part in [the official round](https://oj.vnoi.info/contest/vnoicup22_r3)!
<!-- Introduce VNOI -->
VNOI Cup is a Competitive Programming ...
VNOI Cup 2022 Round 3 [Mirror invitation], Yet again, hello Codeforces!
126.
IOI 2022 Country Standings Hello everyone!
Similar to [last year](https://codeforces.com/blog/entry/92631), these are the country standings for IOI 2022 based on the sum of scores of all contestants. Check the spoiler at the bottom for the complete list.
<table style="width:100%">
<tr>
<th>Rank</th>
<th>Team</th>
<th>Score</th>
</tr>
<tr> <td>1</td><td>CHN</td><td>2310 </td></tr>
<tr> <td>2</td><td>USA</td><td>1909 </td></tr>
<tr> <td>3</td><td>JPN</td><td>1871 </td></tr>
<tr> <td>4</td><td>IOI_2</td><td>1725 </td></tr>
<tr> <td>5</td><td>KOR</td><td>1624 </td></tr>
<tr> <td>6</td><td>CAN</td><td>1504 </td></tr>
<tr> <td>7</td><td>TWN</td><td>1502 </td></tr>
<tr> <td>8</td><td>UKR</td><td>1500 </td></tr>
<tr> <td>9</td><td>IRN</td><td>1448 </td></tr>
<tr> <td>10</td><td>ROU</td><td>1387 </td></tr>
</table>
<spoiler summary="Complete list">
<table style="width:100%">
<tr>
<th>Rank</th>
<th>Team</th>
<th>Score</th>
</tr>
<tr> <td>1</td><td>CHN</td><td>2...
IOI 2022 Country Standings, Hello everyone!
127.
Educational Codeforces Round 127 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1671] [contest:1671] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-04-21] Dalabaev, Vladimir [user:vovuh,2022-04-21] Petrov, Ivan [user:BledDest,2022-04-21] Androsov, Mak...
Hello Codeforces! On [contest_time:1671] [contest:1671] will start. Series of
Educational
Announcement of Educational Codeforces Round 127 (Rated for Div. 2)
128.
Ten years of competitive programming 2 Hey Codeforces!
I’m AmirReza PourAkhavan, Codeforces Contest Coordinator. I let the story become complete and I’m sharing it now.
The story is about a 16-year competitive programmer, who left his family and migrated to another city alone to follow competitive programming. After seven years, he advanced to the International Collegiate Programming Contest World Finals, twice.
Read the previous post [here](https://codeforces.com/blog/entry/107465).
10th grade
===
Trying alone
------------------
In my tenth grade, the situation got worse. Before that, at least, I had some colleagues and at least a class per two weeks. But in the new grade, these brights disappeared too. Still, I was trying to do it alone. I remember when I learned the Dijkstra shortest-path algorithm and implemented it for the first time, how happy I was.
Suddenly, my rating growth started. As you can see, my rating in Oct ‘14 was 1057 (minimum rating) and In Feb ‘15 I achieved 1761. Those years, >= ...
, Alireza Tofighi ([user:ATofighi,2022-11-07]) to call me when the results were
published. On the
129.
Educational Codeforces Round 132 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1709] [contest:1709] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-07-20] Dalabaev, Vladimir [user:vovuh,2022-07-20] Petrov, Ivan [user:BledDest,2022-07-20] Androsov, Mak...
Hello Codeforces! On [contest_time:1709] [contest:1709] will start. Series of
Educational
Announcement of Educational Codeforces Round 132 (Rated for Div. 2)
130.
Educational Codeforces Round 122 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1633] [contest:1633] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-01-30] Dalabaev, Vladimir [user:vovuh,2022-01-30] Petrov, Ivan [user:BledDest,2022-01-30] Androsov, Mak...
Hello Codeforces! On [contest_time:1633] [contest:1633] will start. Series of
Educational
Announcement of Educational Codeforces Round 122 (Rated for Div. 2)
131.
Pinely Treasure Hunt Contest Hello, codeforces!
Pinely is a high-frequency trading company. We trade at the exchanges all over the world. This year we are the sponsors of the online PTZ competitive programming camp. We have prepared a fun contest for camp participants and invite everybody to join it on CodeForces!
[Pinely Treasure Hunt Contest](https://codeforces.com/contests/1639) will be held on Saturday, [contest_time:1639].
The participants will be offered to solve an interactive optimization problem with open tests and will have 3.5 hours to work on it. You can join individually or in teams of up to 3 people. The contest will be **unrated**.
Winners among camp participants as well as the 3 best teams in overall standings will be awarded with pinely t-shirts.
Since the contest is targeted for participants of the PTZ training camp, it'll be most interesting for **participants with codeforces rating 2000+**.
We are grateful to [user:MikeMirzayanov,2022-02-03] for the opportunity to host the conte...
Hello, codeforces! Pinely is a high-frequency trading company. We trade at the
exchanges all
Announcement of Pinely Treasure Hunt Contest
132.
Invitation to Insomnia Qualifier 2022 Hello Codeforces!
Computer Club, MNNIT Allahabad, India is glad to invite you to the annual programming competition of MNNIT, INSOMNIA, which is an ACM-ICPC style team programming contest of 2.5 hours duration held on Codeforces during its annual technical fest Avishkar. The team can consist up to 3 members.
<b>Contest Details: </b>
<ol>
<li> Qualifiers: </li>
<ul>
<li> Start Time: Wednesday, November 9, 21:00 IST</li>
<li> Duration: 2.5 hours</li>
</ul>
<li> Finals: </li>
<ul>
<li> Start Time: Sunday, November 13, 12:00 IST</li>
<li> Duration: 2.5 hours</li>
</ul>
</ol>
**Top 25** global teams, and **Top 25** teams from MNNIT (based on the result of Qualifiers) will qualify to the Finals. The prize distribution for global teams is mentioned below: <br>
Teams consisting of MNNIT students only will be eligible for a seperate prize pool.
Register your team for the qualifiers here: https://forms.gle/BKsbKfoGzSxC394R8 <br>...
Invitation to Insomnia Qualifier 2022, Hello Codeforces!
133.
Codeforces Round #847 (Div. 3) Hello! [contest:1790] will start at [contest_time:1790]. You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.
The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of **open hacks**.
You will be given **6-8 problems** and **2 hours and 15 minutes** to solve them.
Note that the **penalty** for the wrong submission in this round is **10 minutes**.
[Remember](https://codeforces.com/blog/entry/59228) that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a _trusted participant of the thi...
Hello! [contest:1790] will start at [contest_time:1790]. You will be offered
6-8 problems with
Announcement of Codeforces Round 847 (Div. 3)
134.
Educational Codeforces Round 124 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1651] [contest:1651] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-03-09] Dalabaev, Vladimir [user:vovuh,2022-03-09] Petrov, Ivan [user:BledDest,2022-03-09] Androsov, Mak...
Hello Codeforces! On [contest_time:1651] [contest:1651] will start. Series of
Educational
Announcement of Educational Codeforces Round 124 (Rated for Div. 2)
135.
Invitation to ICPC de Tryst and CodeMod 2022 (ANCC, IIT Delhi) Hello Codeforces!
The Algorithms and Coding Club, IIT Delhi (ANCC) in collaboration with Tryst, IIT Delhi, will host the following two events and would like to invite you all for the same:
- ICPC De Tryst on [Friday April 15, 2022 at 21:00 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=ICPC+De+Tryst&iso=20220415T21&p1=176&ah=4).
- CodeMod on [Sunday April 17, 2022 at 09:00 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CodeMod&iso=20220417T09&p1=176&ah=3).
Participation is open to all, but the prizes are only for Indian college students. We encourage everyone to participate in these contests.
---
## ICPC de Tryst
$\textbf{ICPC de Tryst}$ is an ICPC style team contest where you would be given 7-9 problems to solve in the span of 4 hours, for teams of 1-3 members.
$\textbf{Details}$:
- Each participant is allowed to use their own laptop.
- Participants will be required to submit their code on Codeforces and will receive a verdi...
Invitation to ICPC de Tryst and CodeMod 2022 (ANCC, IIT Delhi), Hello Codeforces!
136.
2022-2023 Winter Petrozavodsk Camp, Day 4: KAIST+KOI Contest Hello!
I uploaded [2022-2023 Winter Petrozavodsk Camp, Day 4: KAIST+KOI Contest](https://codeforces.com/gym/104345) to the CF Gym.
Problems are from KAIST 12th ICPC Mock Competition, with the exception of A, B (KOI 2022 Finals), and C (hard to explain).
Problems are authored by:
* ABC: [user:ko_osaga,2023-05-05]
* D: [user:circle-oo,2023-05-05], [user:queued_q,2023-05-05]
* EKL: [user:mo_onrabbit2,2023-05-05]
* F: [user:mo_onrabbit2,2023-05-05] [user:gs18115,2023-05-05] [user:retro3014,2023-05-05]
* GI: [user:gs18115,2023-05-05]
* J: [user:queued_q,2023-05-05]
* HM: [user:kclee2172,2023-05-05]
I could be wrong, and I wish I am, but it feels like this is the last camp contest I will organize. Hope you had fun participating in the contest, as much as I enjoyed preparing the contest so much!
<spoiler summary="List of relevant previous contests">
* [XVIII Open Cup. GP of Korea](https://codeforces.com/blog/entry/57528)
* [KAIST RUN Spring Contest 2018](https://...
2022-2023 Winter Petrozavodsk Camp, Day 4: KAIST+KOI Contest, Hello!
Announcement of 2022-2023 Winter Petrozavodsk Camp, Day 4: KAIST+KOI Contest
137.
Codeforces Round #833 (Div. 2) Hello, Codeforces! (or as we say in romanian, _"Nu renunţ la tine niciodată"_)
I am glad to invite everyone to participate in [contest:1748], which will be held on [contest_time:1748].
This round will be rated for all participants with rating lower than **2100**.
You will be given **6** problems and **2 hours** to solve them. All of the problems are authored by me.
I would like to thank the following people, without whom this round would not have been possible:
- [user:IgorI,2022-11-09] for his awesome coordination of the round and for helping me with problem preparation.
- [user:feecle6418,2022-11-09], [user:Sserxhs,2022-11-09], [user:Gary2005,2022-11-09], [user:RUSH_D_CAT,2022-11-09], [user:atodo,2022-11-09], [user:BucketPotato,2022-11-09], [user:andrei_boaca,2022-11-09], [user:hochesh,2022-11-09], [user:JohnVictor,2022-11-09], [user:cadmiumky,2022-11-09], [user:powergee101,2022-11-09], [user:mejiamejia,2022-11-09], [user:jampm,2022-11-09], [user:alin_gb18,2022-11-...
Hello, Codeforces! (or as we say in romanian, _"Nu renunţ la tine niciodată"_)
I am glad to
Announcement of Codeforces Round 833 (Div. 2)
138.
2022-2023 Winter Petrozavodsk Camp, Day 2: GP of ainta Hello!
I uploaded [2022-2023 Winter Petrozavodsk Camp, Day 2: GP of ainta](https://codeforces.com/gym/104427) to the CF Gym.
It is the collection of problems authored by [user:ainta,2023-06-12] in 2015-2022. This contest is not related to me, I'm just stealing his contribution points.
Thanks to [user:tlwpdus,2023-06-12], who found a solution to one of the problems.
Enjoy!
<spoiler summary="List of relevant previous contests">
* [XVIII Open Cup. GP of Korea](https://codeforces.com/blog/entry/57528)
* [KAIST RUN Spring Contest 2018](https://codeforces.com/blog/entry/59625)
* [XIX Open Cup. GP of Korea](https://codeforces.com/blog/entry/62435)
* [XIX Open Cup. GP of Daejeon](https://codeforces.com/blog/entry/66883)
* [XX Open Cup. GP of Korea](https://codeforces.com/blog/entry/70510)
* [2020-2021 Summer Petrozavodsk Camp, Day 6: Korean Contest](https://codeforces.com/blog/entry/88406)
* [XXI Open Cup. GP of Korea](https://codeforces.com/blog/entry/83511)
*...
2022-2023 Winter Petrozavodsk Camp, Day 2: GP of ainta, Hello!
Announcement of 2022-2023 Winter Petrozavodsk Camp, Day 2: GP of ainta
139.
2022 Harker Programming Invitational Hello Codeforces!
The Harker Programming Club would love to invite middle school and high schoolers to our Harker Programming Invitational (HPI) 2022 event on [Sunday, March 13 from 8:00 AM to 2:45 PM PST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=HPI+2022&iso=20220313T08&p1=224&ah=8). This year the theme of our contest will be “CS & Space.”
The Harker Programming Invitational is a one-day event consisting of a programming contest, keynote speech, panel discussion, and awards, with the goal to inspire and empower students to participate in computer science, technology, and AI. The competition will provide aspiring students with the opportunity to solve creative programming problems, while the keynote speech and panel discussion aim to give the participants insight into the fields within Computer Science and Space.
Teams of up to 3 students will participate in the regular and tiebreaker rounds, which are 1.5 and 1 hour long, respectively. There will be two divis...
2022 Harker Programming Invitational, Hello Codeforces!
140.
The Brazilian IOI 2023 Team was selected and it is stacked Hello codeforces!
Because of weird scheduling issues, the brazilian TST is normally made at december of the year before IOI, different from the rest of the countries. So, today was the last day of TST and after 4 days of contests we have our team settled:
From left to right, we have:
- Leonardo Valente Nascimento ([user:definitelynotmee,2022-12-10])
- Rafael Nascimento Soares ([user:Deepesson,2022-12-10])
- Arthur Lobo Leite Lopes ([user:LoboLobo,2022-12-10])
- Pedro Suyama Leston Rey ([user:pedroslrey,2022-12-10])
In case youre curious, here is a screenshot of the scoreboard so you can see how everyone went.
We were quite comfortably above 5th place in the end, but i had a headache on the first day so i wasn't even top 4 on it. The problems were also really good, as they typically are (even though i can't say the same...
Hello codeforces! Because of weird scheduling issues, the brazilian TST is
normally made at
141.
Invitation to TLX Regular Open Contest #29 <img width="350px" src="/predownloaded/2d/30/2d30c17aba8882b75b0b9b0aa7c222a519bcc7ba.png">
Hello, Codeforces! Hope you are ready to do some laundry!
We are excited to invite you to <b>TLX Regular Open Contest (TROC) #29!</b>
Key details:
<ul>
<li>Contest links: [TLX](https://tlx.toki.id/contests/troc-29)</li>
<li> Time: [5th December 2022, 13:05 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=TLX%20Regular%20Open%20Contest%20%2329&iso=20221205T130500)</li>
<li> Writer: [user:Zappeko,2022-12-02]</li>
<li> Duration: 2 hours </li>
<li> Problems: 8 <strike>buttons</strike> </li>
<li> Scoring distribution: <b>100 — 200 — 300 — 450 — 500 — 550 — 650 — 700 </b> </li>
</ul>
I would like to thank:
<ul>
<li> [user:Pyqe,2022-12-02] and [user:steven.novaryo,2022-12-02] for their help in coordinating the round and in preparing the problem components.</li>
<li> [user:Kinon,2022-12-02], [user:Drew_,2022-12-02], and [user...
"> Hello, Codeforces! Hope you are ready to do some laundry! We are excited to
invite you toTLX
142.
SIT & JUB STAR Contest 2022 <center>
<img alt="SIT" src="https://codeforces.com/predownloaded/b7/59/b7597e61079718f49f275cfc2b343e9c1461bb78.png" style="float:right; height: 250px; margin: 10px; max-width:50%;"/>
</center>
Hello, Codeforces!
We are thrilled to announce the dates of our annual online programming competition, the **SIT & JUB STAR Contest 2022**, organized by the Schaffhausen Institute of Technology (SIT) in Switzerland and our partner Jacobs University Bremen (JUB) in Germany.
Winners will have the chance to receive exciting prizes, including a full scholarship for
**Master in Computer Science and Software Engineering** program.
**<font color="#00a987">What is the SIT & JUB STAR Contest?</font>**
The goal of the SIT & JUB STAR Contest is to promote interest in the field of Computer Science and Software Engineering, giving participants an opportunity to demonstrate their knowledge of programming. It is also a winning ticket for full scholarship to a master program. To partici...
SIT & JUB STAR Contest 2022, Hello, Codeforces!
143.
Hello 2022 Editorial Thank you for participation! Here is the editorial:
[problem:1621A]
<spoiler summary="Editorial">
[tutorial:1621A]
</spoiler>
<spoiler summary="Solution">
[submission:141571728]
</spoiler>
[problem:1621B]
<spoiler summary="Editorial">
[tutorial:1621B]
</spoiler>
<spoiler summary="Solution">
[submission:141572205]
[Solution with sets](https://codeforces.com/contest/1621/submission/141572289)
</spoiler>
[problem:1621C]
<spoiler summary="Editorial">
[tutorial:1621C]
</spoiler>
<spoiler summary="Solution">
[submission:141572393]
</spoiler>
[problem:1621D]
<spoiler summary="Editorial">
[tutorial:1621D]
</spoiler>
<spoiler summary="Solution">
[submission:141572457]
</spoiler>
[problem:1621E]
<spoiler summary="Editorial">
[tutorial:1621E]
</spoiler>
<spoiler summary="Solution">
[submission:141572555]
</spoiler>
[problem:1621F]
<spoiler summary="Editorial">
[tutorial:1621F]
</spoiler>
<spoiler summary="Sol...
Hello 2022 Editorial
Tutorial of Hello 2022
144.
Codeforces Round #875 (Div. 1, Div. 2) Hello, Codeforces! Or, as we like to say in Romania: Sus Sus Sus, ca la [**Strehaia**](https://en.wikipedia.org/wiki/Strehaia) tată!
I am glad to finally invite you to participate in [contest:1830] and [contest:1831], which will start on [contest_time:1830]. In both divisions, you will be given **6** problems and **2 hours and 30 minutes** to solve them.
The problems were authored and prepared by [user:Andrei_ierdnA,2023-05-25], [user:Doru,2023-05-25], [user:Gheal,2023-05-25], [user:IacobTudor,2023-05-25], [user:LucaLucaM,2023-05-25], [user:RedstoneGamer22,2023-05-25], [user:SlavicG,2023-05-25], [user:Sochu,2023-05-25], [user:alecs,2023-05-25], [user:andrei_boaca,2023-05-25], [user:andrei_iorgulescu,2023-05-25], [user:lucaperju,2023-05-25], [user:valeriu,2023-05-25] and me ( <a class='rated-user user-gray' href='/profile/tibinyte'title='Cheater tibinyte'>tibinyte</a> ).
I would like to thank:
- [user:errorgorn,2023-05-25], for his wonderful coordination.
- [user:irkst...
Hello, Codeforces! Or, as we like to say in Romania: Sus Sus Sus, ca la
[**Strehaia**](https
Announcement of Codeforces Round 875 (Div. 1)
Announcement of Codeforces Round 875 (Div. 2)
145.
Educational Codeforces Round 138 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1749] [contest:1749] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-10-19] Dalabaev, Vladimir [user:vovuh,2022-10-19] Petrov, Ivan [user:BledDest,2022-10-19] Androsov, Mak...
Hello Codeforces! On [contest_time:1749] [contest:1749] will start. Series of
Educational
Announcement of Educational Codeforces Round 138 (Rated for Div. 2)
146.
XXII Open Cup: Gp of ByteDance Hello! I'm happy to announce XXII Open Cup: Grand Prix of ByteDance, which will be held on July 24th, 2022.
This contest is first used in ByteDance Programming Camp 2022 on July 15th as the Final contest. It is organized by me, and prepared by 14 experienced problem setters who set at least 22 EC ICPC contests and 10 CCPC contests over the past 7 years. We believe this contest is both challenging, fun and might even be educational for teams.
Here representing the whole contest setting committee, I want to express our gratefulness to ByteDance for organizing this great camp and sponsor this contest, Oleg Hristenko for providing technical support, and our testing team ([user:mayaohua2003,2022-07-21], [user:gtrhetr,2022-07-21], [user:142857,2022-07-21]) and our coaches ([user:MiracleFaFa,2022-07-21], [user:Jiry_2,2022-07-21], [user:Claris,2022-07-21], [user:Gromah,2022-07-21]) for their help.
Problem Setters: [user:quailty,2022-07-21], [user:Claris,2022-07-21], [user:Gromah,2022-...
Hello! I'm happy to announce XXII Open Cup: Grand Prix of ByteDance, which will
be held on July
147.
Fixing the contest management mess ...or "How legacy systems fight obstacles no sane person would introduce in the first place".
Hello, Codeforces!
I am sure that those of you who tried to host their own programming competitions or write their own utilities for contest management are aware of the state of affairs regarding contest hosting. There are lots of incompatible formats, no one knows exactly how stuff ought to work, Polygon is full of nondescript and seemingly contradictory options, ej-polygon never seems to work quite correctly, modifications have to be applied to jury archives to make them work on your particular installation, non-trivial problem types require constant maintenance and hacks, *ad infinitum*.
Personally, I stumbled upon all these problems when I tried to get my own judge system working and suddenly discovered that the difficult part is not judging complex problems, but handling artificial complexity introduced by legacy software and standards. So here I am, attempting to solve these pro...
". Hello, Codeforces! I am sure that those of you who tried to host their own
programming competitions
148.
California Informatics Competition (CALICO) Spring '23 Hello Codeforces!
We are excited to invite you to compete in the California Informatics Competition (CALICO) Spring '23! The contest will take place on [Saturday, April 8, 2023 from 4:00 p.m. to 6:30 p.m. Pacific Time](https://timeanddate.com/s/430d). **Registrations are now open** and will be until Thursday, April 6, 2023 at 11:59 p.m. Pacific Time, so [register here while you can](https://calico.cs.berkeley.edu/register)! The contest will take place virtually on our [custom judge platform](https://calicojudge.com/).
The California Informatics Competition (CALICO) is a semiannual team programming contest organized by students at the University of California, Berkeley. We create original problems to encourage students to grow their problem-solving skills and learn algorithms in fun and exciting ways. Check out our [website](https://calico.cs.berkeley.edu/) to learn more about the contest and join our [discord server](https://discord.gg/RTdxtzXQZ5) to get announcements, make teams...
Hello Codeforces! We are excited to invite you to compete in the California
Informatics
149.
Brazilian Bizarre Adventures at the TST Hello codeforces!
I was reminiscing about the brazilian TST that just happened and figured it was way too crazy not to share with everyone how it went. So as a follow up to [this blog](https://codeforces.com/blog/entry/109950) I'll be going through my experiences at the event. Get ready for a ride, because this is gonna be a long one.
Day of Arrival: Coming out of the closet
------------------
The people of my school all gathered in a bus to go to the hotel we were staying at. That bus made a beeping noise every time we passed 90 km/h, and considering we were travelling at night, we were hearing that noise way too often! While in the ride, I stole [user:LFFB_,2022-12-11]'s laptop and started playing Osu on it. Even though I was playing on the touchpad and the bus was bumping around, I was able to clutch out an S on "Pepsi Man", which was quite a challenge despite being on relax mode.
 =$ the number of edges in the simple path $a \rightarrow b$.
A diameter of the tree $a \rightarrow b$ is the longest path, i.e., the one that maximizes $\text{dist}(a, b)$ over all pairs of nodes. If there are multiple diameters, let's pick any of them.
The same definition is valid for a weighted tree with nonnegative weights (with $\text{dist}(a, b) =$ the sum of the weights of the edges in the simple path $a \rightar...
Hello everyone,
finding the diameter is one of the most frequent ways to solve problems about
151.
Hello Muscat 2023 **<font color="#625bb7">Hello, Codeforces!</font>**
It is the last call to register for the 2nd “Hello Muscat 2023” ICPC programming bootcamp, the continuation of the “Hello” bootcamp series, organised by **<font color="#625bb7">Harbour.Space University</font>**, in collaboration with **<font color="#625bb7">PhazeRo</font>**, **<font color="#625bb7">Gutech</font>**, **<font color="#625bb7">UK Oman Digital Club</font>**, **<font color="#625bb7">Leagues of Code</font>**, **<font color="#625bb7">Gutech CS Club</font>** and **<font color="#625bb7">Codeforces</font>**!
We are inviting all of you to join us from **<font color="#625bb7">March 8th to March 16th, 2023 in Muscat, Oman for an intense 8 days of programming</font>**! It is not only a great opportunity to train but also a chance to discover a new amazing country. **March is an especially great time to visit Oman if you want to enjoy nice beach weather — don’t miss it!**
As always, we can’t wait to see you there to l...
Hello Muscat 2023, **Hello, Codeforces!** It is the last call to register for the 2nd, , smoothing your road towards the joined World Finals 2022 and 2023 in Egypt!, 2022 and 2023 to join our Bootcamp for FREE online. Please register using a
promo code
152.
Educational Codeforces Round 125 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1657] [contest:1657] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-03-21] Dalabaev, Vladimir [user:vovuh,2022-03-21] Petrov, Ivan [user:BledDest,2022-03-21] Androsov, Mak...
Hello Codeforces! On [contest_time:1657] [contest:1657] will start. Series of
Educational
Announcement of Educational Codeforces Round 125 (Rated for Div. 2)
153.
Testlib: tests + CI Hello, Codeforces.
I have wanted for a long time and now, finally, I sat down and did it.
Many of you are familiar with my [Testlib](https://github.com/MikeMirzayanov/testlib) project. This is a library that helps you develop problems if you are using C++.
In the case of problems for Codeforces rounds, its use is mandatory. It seems to me that it is almost a de facto standard for preparing materials for completely different olympiads and competitions.
The history of С++-Testlib is almost lost in centuries, I published the first version in 2005.
Nowadays, making edits to Testlib has become tricky. The code grown to thousands of lines, also it has too long a history.
This increases the likelihood of accidentally changing some aspect of behavior, which will jeopardize the holding of a Codeforces round or another important competition.
In short, making a bug in this code or changing behavior anywhere is highly discouraged.
So I recently took the plunge and wrote some test...
Hello, Codeforces. I have wanted for a long time and now, finally, I sat down
and did it
154.
Happy New Year! **Hello guys!**
**The new year is coming to an end, so I wish everyone a happy New year!**
This post is the [conclusion](http://codeforces.com/blog/entry/108044) of this mini-competition, just summing up the results :). In the last post, I couldn't mention everyone who left their comments, but I hope I didn't forget about anyone in this one! From below you can see how your rank has changed since the beginning of this mini-competition(Left one — Old, Right one — New), I hope that almost everyone has been able to achieve their goals, and those who have not achieved them will have another wonderful year for this!
### **Happy New Year Codeforces!**
### International grandmaster!
[user:Vercingetorix,2022-10-17] • [user:Vercingetorix,2023-01-01]!
### Grandmasters!
[user:jjang36524,2022-10-17] • [user:jjang36524,2023-01-01]!
[user:SecondThread,2022-10-17] • [user:SecondThread,2023-01-01]!
[user:anpoli99,2022-10-17] • [user...
**Hello guys!** **The new year is coming to an end, so I wish everyone a happy
New year
155.
Help the Egyptian girls fly to EGOI 2022! Hello Codeforces,
My name is Shahd. I am a bronze medalist in EOI (Egyptian Olympiad in Informatics) 3 times in a row, a silver medalist in the ACPC girls, 5th place in the AFPC in Jordan and 1st place in the IIOT onsite qualifications.
I am a member of the Egyptian EGOI 2022 team. We have practiced very hard for this particular competition. [user:Bakry,2022-09-30] [user:Ahmadsm2005,2022-09-30] [user:AbdelmagedNour,2022-09-30] are training us for EGOI 2022.
Unfortunately, due to the high registration fees for non-European countries, we are unable to cover our costs. We attempted to contact some Egyptian tech companies but there are no updates until now.
We decided to create a [crowdfunding campaign](https://gogetfunding.com/help-the-egyptian-girls-team-fly-to-egoi-2022-2/) as we don't have any other option.
Please donate [here](https://gogetfunding.com/help-the-egyptian-girls-team-fly-to-egoi-2022-2/)
By sharing this blog or donating, you are helping the Egyptian team ...
Help the Egyptian girls fly to EGOI 2022!, Hello Codeforces,
156.
Codeforces Round #848 (Div. 2) Hello, Codeforces!
[user:adnan_toky,2023-01-23] and I are super thrilled to invite everyone to participate in [contest:1778], which will be held on [contest_time:1778].
This round is rated for the participants with ratings strictly **lower than 2100**. You will be given **6 problems** and **2 hours** to solve them. All the problems are authored and prepared by [user:adnan_toky,2023-01-25] and me. To get the 6 problems approved, we needed to propose 12 problems in total <a href="https://emoji.gg/emoji/6390-sneaky-wink-catto"><img src="https://cdn3.emoji.gg/emojis/6390-sneaky-wink-catto.png" width="16px" height="16px" alt="sneaky_wink_catto"></a>.
**UPD:** Score distribution: $500-1000-1250-1750-2250-2750$
We would like to thank:
- [user:darkkcyan,2022-02-12] for incredible coordination and help with the problem preparation
- [user:Alexdat2000,2022-07-16] for the Russian translations and precious help regarding the statements and limits
- [user:KAN,2023-01-30] for upgrad...
Hello, Codeforces! [user:adnan_toky,2023-01-23] and I are super thrilled to
invite everyone to
Announcement of Codeforces Round 848 (Div. 2)
157.
XXII Open Cup. Grand Prix of Daejeon Hello!
[XXII Open Cup. Grand Prix of Daejeon](https://official.contest.yandex.ru/opencupXXII/contest/35265/enter) will be held in [2022/03/27 Sunday, 17:00 KST (UTC+9)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=GP+of+Daejeon+2022&iso=20220327T17&p1=3999&ah=5). **The date of March 27 is final**.
Daejeon is home to [KAIST](https://en.wikipedia.org/wiki/KAIST), but the contest itself has little to do with it, it just inherits the spirit of 2019 Daejeon GP.
The contest was used as a Day 2 Contest for Petrozavodsk Winter Camp 2022. I'm sorry for the camp participants over the lack of editorial. I will work to publish the full editorials right after the GP.
Problems were authored by [user:ko_osaga,2022-02-26], [user:GyojunYoun,2022-02-26], [user:nell_jwk,2022-02-26], [user:Diuven,2022-02-26], [user:queued_q,2022-02-26], [user:jh05013,2022-02-26]. Special thanks to [user:xiaowuc1,2022-02-26] for reviewing the statements.
For external accounts, the contest is re...
Hello! [XXII Open Cup. Grand Prix of
Daejeon](https://official.contest.yandex.ru/opencupXXII
Announcement of XXII Open Cup, Grand Prix of Daejeon
158.
Educational Codeforces Round 126 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1661] [contest:1661] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-04-08] Dalabaev, Vladimir [user:vovuh,2022-04-08] Petrov, Ivan [user:BledDest,2022-04-08] Androsov, Mak...
Hello Codeforces! On [contest_time:1661] [contest:1661] will start. Series of
Educational
Announcement of Educational Codeforces Round 126 (Rated for Div. 2)
159.
Educational Codeforces Round 130 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1697] [contest:1697] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-06-11] Dalabaev, Vladimir [user:vovuh,2022-06-11] Petrov, Ivan [user:BledDest,2022-06-11] Androsov, Mak...
Hello Codeforces! On [contest_time:1697] [contest:1697] will start. Series of
Educational
Announcement of Educational Codeforces Round 130 (Rated for Div. 2)
160.
Codeforces Round #765 (Div. 2) Hello, Codeforces!
We invite you to [Codeforces Round #765 (Div. 2)](https://codeforces.com/contest/1625), which will take place in [contest_time:1625]. Note the unusual contest start time. <b>This round will be rated for all the participants whose ratings are lower than 2100.</b>
You will have to solve 5 problems in 2 hours. One of the problems will be divided into easy and hard version. The round is based on the problems from Belarusian Regional olympiad. <b>We kindly ask all Belarusian pupils who participated in this olympiad, to refrain from taking part in this round and discussing the problems publicly before the round ends.</b>
Thanks to everyone who helped to prepare this contest:
- Our coordinators, [user:KAN,2022-01-11] and [user:isaf27,2022-01-11] for good coordination.
- [user:Wind_Eagle,2022-01-11], [user:gepardo,2022-01-11], [user:VEGAnn,2022-01-11], [user:andrew,2022-01-11] for help in preparing the round.
- [user:programmer228,2022-01-11], [user:Vladik,2022...
Hello, Codeforces! We invite you to [Codeforces Round #765 (Div.
2)](https://codeforces.com
Announcement of Codeforces Round 765 (Div. 2)
161.
GeeksforGeeks's Code India Code Hello Codeforces,
I am happy to invite you to GeeksforGeeks's Pan-India Coding Contest – Code India Code. Showcase your coding skills and win rewards up to **INR 7 Lakhs**.
Contest Details are as follows:
**Qualification Round:** ([Register Here](https://practice.geeksforgeeks.org/contest/gfg-mega-contest-qualification-round/?utm_source=CF&utm_medium=CF-inf&utm_campaign=CF-CIC))
- **Sunday, 6th March 2022**, 12:00 AM (IST) to 7th March 2022,12:00 AM (IST)
- In order to qualify in the first round, the participant needs to solve a minimum of 1 question out of 4 in 24 hours.
**Final Round:**
- **Thursday, 10 March 2022**, 7:30 PM to 10:00 PM IST
- Only those who qualify in the first round will receive a link to the final round.
**Prizes:**
- Rank 1: Macbook Pro + Course voucher worth INR 12,000
- Rank 2: iPad Air + Course voucher worth INR 7,000
- Rank 3: Smart Watch + Course Voucher worth INR 3,000
- Rank 4-25: Tablets + Course Voucher upto INR 1500
- Ra...
Hello Codeforces, I am happy to invite you to GeeksforGeeks's Pan-India Coding
Contest – Code
162.
Invitation to Spybits CP Contest, Udyam'22 — IIT(BHU) Varanasi Hello Everyone!<br>
We would like to invite you all to participate in the [SPYBITS2022 CONTEST-2](https://www.codechef.com/SPY22022) aka the Spybits CP Contest, under the banner of Udyam'22, IIT (BHU) Varanasi. The contest will be held on [5th April 2022 at 19:05 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=SPYBITS+2022+CONTEST-2&iso=20220405T1905&p1=176&ah=2&am=30).
Udyam is the annual technical fest of the Department of Electronics Engineering, Indian Institute of Technology (BHU),Varanasi. To know more about Udyam, please visit the official website of [Udyam'22](https://www.udyamfest.com/).
We would like to thank our Title Sponsor, Cisco and Event Sponsor, Nullcon.
Spybits CP Contest is the second round of the SPYBITS event, in which your algorithmic problem solving skills are tested. This contest is open to everyone, so you can appear in the contest even if you haven't registered for the SPYBITS event.
All the problems have been prepared by [user:X...
Hello Everyone!
We would like to invite you all to participate in the [SPYBITS2022 CONTEST-2
163.
Educational Codeforces Round 134 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1721] [contest:1721] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-08-26] Dalabaev, Vladimir [user:vovuh,2022-08-26] Petrov, Ivan [user:BledDest,2022-08-26] Androsov, Mak...
Hello Codeforces! On [contest_time:1721] [contest:1721] will start. Series of
Educational
Announcement of Educational Codeforces Round 134 (Rated for Div. 2)
164.
Educational Codeforces Round 137 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1743] [contest:1743] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Ivan [user:BledDest,2022-10-16] Androsov, Alex [user:fcspartakm,2022-10-16] Frolov and me. Also huge thanks to Mike [user:MikeMirza...
Hello Codeforces! On [contest_time:1743] [contest:1743] will start. Series of
Educational
Announcement of Educational Codeforces Round 137 (Rated for Div. 2)
165.
California Informatics Competition (CALICO) Fall '22 Hello Codeforces!
We are excited to invite you to compete in the California Informatics Competition (CALICO Fall ‘22)! The contest will take place on [Saturday, November 26, 2022 from 4:00 p.m. to 7:00 p.m. Pacific Time](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CALICO+Fall+%2722+Online&iso=20221126T16&p1=791). **Registrations are now open** and will be until Wednesday, November 23, 2022 at 11:59 p.m. Pacific Time, so [register here while you can](https://forms.gle/WdN5RGoHTP4g4Gjz8)! The contest will take place virtually on our [custom judge platform](https://calicojudge.com/).
The California Informatics Competition (CALICO) is a semiannual team programming contest organized by students at the University of California, Berkeley. We create original problems to encourage students to grow their problem-solving skills and learn algorithms in fun and exciting ways. Check out our [website](https://calico.berkeley.edu/) to learn more about the contest and join our [disc...
Hello Codeforces! We are excited to invite you to compete in the California
Informatics
166.
My Experience at ICPC Dhaka World Finals 2022 Hello, Codeforces!
I participated at the Dhaka World Finals last month, and decided to write a blog about it. It's been a while since I've written, so I also decided to talk about a few other things: Indian regionals, Moscow World Finals, NAC, etc. So read on to know how I qualified for 3 World Finals across 2 continents and 6 different teammates, how my teammates got COVID at Moscow (and I was about to participate solo), getting the best rank IIT Bombay has ever gotten with a man down, and absolute devastation at Dhaka. I try to give an insight into the non-programming aspects as far as possible, while also trying to highlight the things to take away from the programming parts.
The blog can be found [here](https://thesestraythoughts.blogspot.com/2022/12/icpc-world-finals-dhaka-2022.html). Thanks to [user:aryanc403,2022-12-27] and [user:lucasxia01,2022-12-27] for testing the blog. Please let me know what you think!
<spoiler summary="Self-plug">
If you're interested in fol...
My Experience at ICPC Dhaka World Finals 2022, Hello, Codeforces!
167.
Codeforces Round #849 (Div. 4) Hello Codeforces!
[user:flamestorm,2022-08-28], [user:SlavicG,2023-02-01], [user:MikeMirzayanov,2022-07-11] and I want to invite you to [contest: 1791].
It starts on [contest_time: 1791].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants...
Hello Codeforces! [user:flamestorm,2022-08-28], [user:SlavicG,2023-02-01],
[user:MikeMirzayanov
Announcement of Codeforces Round 849 (Div. 4)
168.
Infoleague Winter 2022 Round 1 Announcement Hello Codeforces!
We would like to invite you to the first official round of Infoleague Winter 2022, starting Saturday, January 8th at 14:00 GMT.
This contest will have 2 divisions, each containing 3 problems, which are not necessarily sorted in increasing order of difficulty. Div 2 is recommended for low-Experts and below (i.e. <1700), while Div 1 is recommended mainly for high experts, CMs and Masters.
Contest links [Div1]( https://codeforces.com/gym/103505), [Div2]( https://codeforces.com/gym/103503)
Contest duration:
- Div 1: 5 hours
- Div 2: 3 hours
Scoring distribution (for both divisions): **100-100-100**
The scoring system is IOI-esque, with full feedback. All problem statements will be available in English.
Problemsetters: [user:Gheal,2022-01-08], [user:tibinyte,2022-01-08], [user:cadmiumky,2021-10-31]
Testers: [user:andrei_boaca,2022-01-08], [user:IacobTudor,2022-01-08], [user:RaresFelix,2022-01-08]
**Upd 1:** The Div. 2 round is over! Co...
Infoleague Winter 2022 Round 1 Announcement, Hello Codeforces!
Announcement of Infoleague Winter 2022 Round 1 Div. 2
Announcement of Infoleague Winter 2022 Round 1 Div. 1
169.
It's time to say goodbye, but not fairwell, to codeforces Hello everyone. I am a codeforcer for two and half years. I took part more than 130 contests, write hundreds of comments and blogs. Now it's time to say goodbye, but not fairwell, to contests. My English is not very good, but my words are sincere.
As a Physics PhD new grad try to become a sofeware engineer, I took part in my first codeforces contest in 2020. My initial reason for the codeforces, is to practice algorithm, since I found it difficult to solve the hard tag problem in leetcode weekly contest, and a experience leetcoder told me: "if you want to solve harder problem in leetcode, try codeforces, and if you can solve 2400 rating problem in codeforces, leetcode problem is just piece of cake. "
So I took part my first contest: educational codeforces 97. The results was very good, I solved four problems and get a ranking of 600+. However, my second contest is a disaster and give me huge lesson. I found it difficult even for reaching blue. I keep practicing, foc...
Hello everyone. I am a codeforcer for two and half years. I took part more than
130 contests
170.
Spain Olympiad in Informatics 2022 Online Mirror Hello!
I invite you to participate in the 26th Spain's Olympiad in Informatics' Online Mirror. This is the first year we are doing the mirror contest and we hope it will be a success. The two contests will start on [2022 April 2 16:00 CEST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Concurso+Espejo+OIE+2022+D%C3%ADa+1&iso=20220402T16&p1=141&ah=4) and [2022 April 3 16:00 CEST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Concurso+Espejo+OIE+2022+D%C3%ADa+2&iso=20220403T16&p1=141&ah=4) and will last 4 hours each.
Contest facts:
- Two 5-tasks contests with OI scoring (subtasks).
- Statements in English and Spanish.
- Problems are **not** ordered by difficulty.
- Problem authors: [user:FelixMP,2022-03-13] [user:EdgarMM19,2022-03-13] [user:BlancaHM,2022-03-13] [user:gog.gerard,2022-03-13]
- The problems will cover a wide range of difficulties, and the subtasks make it possible to progress in all problems, so it should be an interesting contest for p...
Spain Olympiad in Informatics 2022 Online Mirror, Hello!
171.
Codeforces Round #823 (Div. 2) Hello, Codeforces!
We invite you to [contest:1730] which will be held on [contest_time:1730]. You will be given **2 hours** to solve **6 problems**.
The problems were invented and prepared by [user:shnirelman,2022-09-24], [user:Lankin,2022-09-24] and me.
We would like to thank:
- [user:isaf27,2022-09-24] for coordinating the round.
- [user:KAN,2022-09-24] for the help during preparation of the contest.
- [user:kevinxiehk,2022-09-24], [user:74TrAkToR,2022-09-24], [user:Aleks5d,2022-09-24], [user:cadmiumky,2022-09-24], [user:satyam_343,2022-09-24], [user:gothic_kobra,2022-09-24], [user:NikitaSemenov,2022-09-24], [user:tibinyte,2022-09-24] for testing the round.
- [user:MikeMirzayanov,2022-09-24] for Codeforces and Polygon.
Wish you good luck and high rating!
The scoring distribution will be announced closer to the beginning of the round.
**UPD**: Scoring distribution: **500 — 1000 — 1500 — 2250 — 2250 — 3000**.
**UPD2**: Edit...
Hello, Codeforces! We invite you to [contest:1730] which will be held on
[contest_time:1730
Announcement of Codeforces Round 823 (Div. 2)
172.
Codeforces Round #773 editorial Hello, codeforces!
We deeply apologize for the weak pretests in the problem [problem:1642C]. Anyway, we believe that you liked at least one problem from the contest :)
Thanks to [user:Mangooste,2022-02-23] for the problem [problem:1641E]!
[tutorial: 1642A]
Solution: [submission:147513897]
[tutorial: 1642B]
[Video-tutorial](https://youtu.be/OD6nZeMinl0) by [user:ak2006,2022-02-23]
Solution: [submission:147513934]
[tutorial: 1642C]
[Video-tutorial](https://youtu.be/iVqD9wlXn7s) by [user:ak2006,2022-02-23]
Solution: [submission:147513962]
`Vector` solution: [submission:147513974]
[tutorial: 1642D]
$\mathcal{O}(2n^2)$ insertions solution: [submission:147514019]
$\mathcal{O}(n^2)$ insertions solution: [submission:147514028]
[tutorial: 1642E]
Solution: [submission:147514055]
`Set` solution: [submission:147514064]
[tutorial: 1642F]
Solution: [submission:147514090]
`Bitset` solution: [submission:147514108]
[tutorial: 1641E]
Solu...
Hello, codeforces! We deeply apologize for the weak pretests in the problem
[problem:1642C
Tutorial of Codeforces Round 773 (Div. 1)
Tutorial of Codeforces Round 773 (Div. 2)
173.
Invitation to ‘Chingari’ CodeChef March Cook-Off (Rated for all) — 5th March ನಮಸ್ಕಾರ ಕೋಡ್ಫೋರ್ಸಸ್ (Hello Codeforces)!
We invite you to participate in CodeChef’s [March Cook-Off](https://www.codechef.com/COOK139?utm_source=codeforces_blog&utm_medium=organic&utm_campaign=COOK139), this Saturday, 5th March, rated for all.
Time: [8 PM — 10:30 PM IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=March+Cook-off+2022&iso=20220305T20&p1=44&ah=2&am=30). Note the [new schedule](https://blog.codechef.com/2022/02/28/were-celebrating-our-birthday-month-and-theres-some-exciting-news-for-you/).
Web3 giant Chingari is onboard to pick their recruits in the areas of Machine Learning, Rust and Web3.
These job openings are for Indians, and Non-Indians (who can work from home), and are experienced in any of the following: Rust, React, Golang,C/ C++, Python, Machine Learning, Deep Learning, Data Mining, Recommendation Systems etc. You’re also a desirable candidate if you have a deep understanding of the blockchain and cryptocurrency space and smart co...
ನಮಸ್ಕಾರ ಕೋಡ್ಫೋರ್ಸಸ್ (Hello Codeforces)! We invite you to participate in
CodeChef’s [March Cook
174.
Codeforces Global Round <strong>22</strong> Hello, Codeforces Addicts!
On [contest_time:1738] we will host [contest:1738]. **<img src="/predownloaded/2e/e2/2ee2f0f95f05aae6ca6f47812dae2dc2aabf277b.png" style="width: 200.0px;float: right;margin: 0 1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">**
[Codeforces Global Round **22**](https://codeforces.com/contest/1738) is the ${\textbf{2}} \cdot {\textbf{2}} = 4$-th round of a 20<strong>22</strong> series of [Codeforces Global Rounds](https://codeforces.com/blog/entry/65002). The rounds are open and rated for everybody.
The prizes for this round:
- 30 best participants get a t-shirt.
- 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.
The prizes for the 6-round series in 20<strong>22</strong>:
- In each round top-100 participants get points according to the [table](https://pastebin.com/QT5sXEaT).
- The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highe...
Hello, Codeforces Addicts! On [contest_time:1738] we will host [contest:1738].
**
Announcement of Codeforces Global Round 22
175.
Invitation to Spybits Number Theory Contest, Udyam'22 — IIT (BHU) Varanasi (Unrated) Hello Everyone!<br>
We would like to invite you all to participate in the [SPYBITS2022 CONTEST-1](https://www.codechef.com/SPYB2022) aka the Spybits Number Theory Contest, under the banner of Udyam'22, IIT (BHU) Varanasi. The contest will be held on [28th Jan 2022 at 20:00 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=SPYBITS2022+CONTEST-1&iso=20220128T20&p1=176&ah=2&am=15).
Udyam is the annual technical fest of the Department of Electronics Engineering, Indian Institute of Technology (BHU),Varanasi. To know more about Udyam, please visit the official website of [Udyam'22](https://www.udyamfest.com/).
Spybits Number Theory Contest is the first round of the SPYBITS event, in which your Number Theory knowledge is tested along with your programming skills. This contest is open to everyone, so you can appear in the contest even if you haven't registered for the SPYBITS event.
All the problems have been prepared by [user:XORring-Samurai,2022-01-21], [user:Laz...
Hello Everyone!
We would like to invite you all to participate in the [SPYBITS2022 CONTEST-1
176.
Invitation to Codechef Starters 65 (InfInITy 2k22) Hello Codeforces !!
We invite you to participate in CodeChef’s [Starters 65](https://www.codechef.com/START65?utm_source=codeforces_blog&utm_medium=organic&utm_campaign=START65) (InfInITy 2k22), this Wednesday, 16th November. This contest is organized by InfInITy 2k22, IIIT Pune.
Time: [8 PM — 11:00 PM IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CodeChef%20Starters%2065&iso=20221116T20&p1=44&ah=3)
The contest is **Rated till 6 Stars** on Codechef.
Joining us on the problem setting panel are:
- Setters: Reyaan [user:reyaan44,2022-11-15] Jagnani, Apoorv [user:apoorv_me,2022-11-15] Kumar, Nishit [user:nishit.sharma,2021-12-28] Sharma, Sahil [user:still_me,2022-11-15] Tiwari, Daksh [user:freaking_fab,2022-07-13] Nahar, Ashu [user:ashu_2004,2022-11-15] Mittal, Amaan [user:amaan0016,2022-11-15] Parvez, Arvind [user:arvind26,2022-11-15] Khandelwal.
- Testers: Utkarsh [user:u...
Hello Codeforces !! We invite you to participate in CodeChef’s [Starters
65](https
177.
Educational Codeforces Round 129 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1681] [contest:1681] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-05-22] Dalabaev, Vladimir [user:vovuh,2022-05-22] Petrov, Ivan [user:BledDest,2022-05-22] Androsov, Mak...
Hello Codeforces! On [contest_time:1681] [contest:1681] will start. Series of
Educational
Announcement of Educational Codeforces Round 129 (Rated for Div. 2)
178.
JOI 2021/2022 Final Round Online Contest Hello, everyone!
[The 21st Japanese Olympiad in Informatics (JOI 2021/2022) Final Round Online Contest](https://contests.ioi-jp.org/joi-ho-2022/index-en.html) will be held from [February 13, 07:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+2021/2022+Final+Round&iso=20220213T07&p1=1440) to [February 13, 11:00 GMT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=JOI+2021/2022+Final+Round&iso=20220213T11&p1=1440). The contest information is as follows:
* Contest duration: **4 hours**
* Number of problems: **5 problems**
* Max score for each task: **100 points**
* Style: **IOI-Style** (There may be some partial scores)
* Problem statement: **Japanese & English**
The registration page will be announced **10 minutes (Fixed)** before the contest start. Details are available in [the contest information page](https://contests.ioi-jp.org/joi-ho-2022/index-en.html).
We welcome all participants. Good luck and have fun!
JOI 2021/2022 Final Round Online Contest, Hello, everyone!
179.
CodeTON Round 8 (Div. 1 + Div. 2, Rated, Prizes!) Hello Codeforcers!
==================
We are pleased to invite you to participate in [contest:1942]. This round will start on [contest_time:1942] and will be **rated for all participants**. There will be $8$ problems to be solved in $3$ hours, with one divided into two subtasks. Similar to [USACO](https://usaco.org/), you will help Farmer John and his cows resolve a series of first world problems. Be there or be square.
This round was cooked up by [user:smax,2024-03-10], [user:sum,2024-03-10], [user:oursaco,2024-03-10], [user:cry,2024-03-13], and [user:buffering,2024-03-10].
We would like to thank the following people for making the round possible:
- Our favorite cherry [user:TheScrasse,2024-03-10] for the wonderful and speedy coordination.
- Our MVP testers, [user:Benq,2024-03-10], [user:Geothermal,2024-03-26], and [user:rainboy,2024-03-26], for dedicating so much time to reviewing problems, providing essential feedback, and perfecting the problemset.
- The rest of ...
Hello Codeforcers! ================== We are pleased to invite you to
participate in [contest
Announcement of CodeTON Round 8 (Div. 1 + Div. 2, Rated, Prizes!)
180.
Invitation to Goodbye Renyin Hello, Codeforces!
It’s our pleasure to invite you to [Goodbye Renyin](https://uoj.ac/contest/80), which takes place on [Friday, January 20, 2023 at 13:00<sup title="timezone offset" style="font-size:8px;">UTC+8</sup>](https://www.timeanddate.com/worldclock/fixedtime.html?msg=The+contest+will+hold+at&iso=20230120T13&p1=33&ah=5).
You will have 5 hours to solve 5 problems sorted roughly by difficulty. Each problem is worth 100 points and may have several subtasks. There might be interactive or output-only problems. The contest is open to everyone, though Codeforces-Div. 1-level contestants are more likely to enjoy it. For details, you may check last year’s [Goodbye Xinchou](https://uoj.ac/contest/74) (only available in Chinese, Simplified).
The problems are authored by [user:changruinian2020,2023-01-17], [user:ix35,2023-01-17], [user:flowerletter,2023-01-17], [user:Melania,2023-01-17] and [user:qingyu,2023-01-17].
The competition format will be similar to (but a bit different...
Hello, Codeforces! It’s our pleasure to invite you to [Goodbye
Renyin](https://uoj.ac/contest/80
181.
CodeTON Round 6 (Div. 1 + Div. 2, Rated, Prizes!) ### Hello, Codeforces!
[user:SomethingNew,2023-09-16] and I are glad to invite you to [contest:1870], which will take place on [contest_time:1870]. You will have 2 hours 15 minutes to solve 8 problems. The round will be rated for everyone.
We would like to thank:
- [user:74TrAkToR,2023-09-16] for coordinating this round.
- [user:isaf27,2023-09-16], [user:ugly2333,2023-09-16], [user:DataStructures,2023-09-16], [user:Little09,2023-09-16], [user:bashkort,2023-09-16], [user:Kieray,2023-09-16], [user:fishy15,2023-09-16], [user:Vladithur,2023-09-16], [user:Dart-Xeyter,2023-09-16], [user:pakhomovee,2023-09-16], [user:makrav,2023-09-16], [user:meowcneil,2023-09-16], [user:127.0.0.1,2023-09-16], [user:Nanani,2023-09-16], [user:nnv-nick,2023-09-16], [user:SomethingDifferent,2023-09-17], [user:vl342,2023-09-16], [user:shiv_codegen,2023-09-17], [user:M1lkas,2023-09-16], [user:allmath,2023-09-16], [user:sdyakonov,2023-09-17] for testing the round and providing useful feedback.
- [user:Mike...
### Hello, Codeforces! [user:SomethingNew,2023-09-16] and I are glad to invite
you to [contest
Announcement of CodeTON Round 6 (Div. 1 + Div. 2, Rated, Prizes!)
182.
Codeforces Round #798 (Div. 2) Hello Codeforces!
We are glad to invite you to [contest:1689] which will start on [contest_time:1689]. **Please notice the unusual time.** You will be given **5** problems and **2** hours to solve them.
The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially in the round.
All problems are prepared by [user:n0sk1ll,2022-06-07] and me. We would like to thank:
- [user:TheScrasse,2022-06-07], [user:nor,2022-06-07], [user:Riblji_Keksic,2022-06-07], [user:AlperenT,2022-06-07], [user:Sarvesh10,2022-06-07] for testing this round and providing valuable feedback!
- [user:DmitryGrigorev,2022-06-07] for coordinating!
- [user:MikeMirzayanov,2022-06-07] for creating amazing Codeforces and Polygon platforms!
Thanks to <a href="https://near.org/">NEAR</a> for supporting this round, details can be found in <a href="https://codeforces.com/blog/entry/101398">this post</a>.
We are looking forward to y...
Hello Codeforces! We are glad to invite you to [contest:1689] which will start
on [contest_time
Announcement of Codeforces Round 798 (Div. 2)
183.
FIICode Contest 2022 Hello CodeForces!
I would like to announce the 7th edition of FIICode – a contest organized by the Faculty of Computer Science Iași.
This year, the contest will be held on CSAcademy and will consist of two rounds, on the 14th and 15th of May. Each round will have 5-6 problems of various difficulties – something like a CF Div 2. The final ranking will be computed by summing up the scores in each of the two rounds.
There will be 7 Romanian and Moldavian winners (read [here](https://fiicode.asii.ro/algoritmica) about prizes), but also the top 5 international competitors will receive T-shirts and other goodies!
The problems are prepared by [user:cristian1997,2022-04-15], [user:Gheal,2022-04-15], [user:lungualex00,2022-04-15], [user:Fanurie,2022-04-15], [user:a_dumi,2022-04-15], [user:vmnechita,2022-04-15], [user:Brodicico,2022-04-15], [user:RazvanPanaite,2022-04-15], [user:IulianOleniuc,2022-04-15], [user:ApetriiRadu,2022-04-15].
**To officially take part in the contest, and...
FIICode Contest 2022, Hello CodeForces!
184.
Shaastra Programming Contest 
Hello Everyone!
On [Saturday, December 26, 2022, at 18:00<sup>UTC+5.5</sup>](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Shaastra+Programming+Contest&iso=20221226T18&p1=553&ah=2), Coding and Logic vertical of [Shaastra](https://shaastra.org/) will be hosting **Shaastra Programming Contest**, and we would like to invite all of you for the same.
Contest Link: [click here]( cutt.ly/SPC_Prelims )
cutt.ly/SPC_Prelims
Fill this form to be considered eligible for participation certificate and prizes — [click here](https://forms.gle/UEpZ6MnV6F5xw3en9) **Note**: Registration on unstop is compulsory but not sufficient.
It will be a combined **unrated** round for all divisions. You can participate in a team of 2 or individually.
[Click here](https://cutt.ly/SPC_Registration) to register for the contest.
**Note**: Only students who have registered will be eligible for prizes.
The...
 Hello
Everyone! On, Hello Everyone! On [Saturday, December 26, 2022, at 18:00UTC+5.5](https
185.
CoDeft 2.0, organised by CP Club, AIT Pune Hello Codeforces,<br>
**Competitive Programming Club, AIT Pune** is excited to invite you to [**CoDeft 2.0**](https://www.codechef.com/CDFT2022) which will take place on [Monday, April 18, 2022 at 21:00 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=CoDeft+2.0&iso=20220418T21&p1=176&ah=2). This contest will be an **ICPC styled** contest to provide an exciting learning platform to showcase your CP skills.
Many thanks to all the people who made this contest possible:
- Problem Setters: [user:RohitRKS,2022-04-13], [user:marksman_,2022-04-13], [user:_AbRn_,2022-04-13] and [user:Free_Electron_,2022-04-13].
- [user:unstoppable_N,2022-04-13], [user:codeict,2022-04-13], [user:fake_name,2022-04-13] and [user:_hecxoc,2022-04-13] for testing and providing detailed feedback that improved the quality and balance of the round significantly.
- [user:CodeSlayer007,2022-04-13] for coordinating the event!
This event will be held in 2 stages:
**Qualifiers**
- Date & Time...
Hello Codeforces,
**Competitive Programming Club, AIT Pune** is excited to invite you to
186.
Invitation to Open Contest Series (topicwise practice contests) Hello Codeforces,
We at [Programming and Algorithms Group, IIT Roorkee](https://www.facebook.com/sdspag) conduct Open Contest Series every year. It will consist of topicwise contests, interspersed with contests with mixed topics. These are aimed at people who want to strengthen their basic concepts via regular practice.
**The problems used in the contests will be past codeforces problems**, and the level of contests will be close to a Div. 3 contest. The duration of contests will vary from 2 to 3 hours.
We welcome you all to join the contests if you believe they can be helpful for you.
Join the group [here](https://codeforces.com/group/T99c3atS1n).
The first contest will be held at [21:00 IST, 13th December 2021](https://www.timeanddate.com/worldclock/fixedtime.html?msg=OCS+Contest-1&iso=20211213T21&ah=2). Further schedule will be updated in the group blog as well as in this blog.
Contest-2: Number Theory -- [9PM IST, 17th December 2021](https://www.timeanddate....
Hello Codeforces, We at [Programming and Algorithms Group, IIT
Roorkee](https://www.facebook.com
187.
Invitation to Tough Duo, April 2022 Hello, Codeforces community!
We are thrilled to invite you to participate in the first-ever rated team contest of **Toph.co**: [Tough Duo, April 2022](https://toph.co/c/tough-duo-april-2022) on April 14, [02:00 PM BST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Tough+Duo%2C+April+2022&iso=20220414T14&p1=73&ah=3). To participate you will have to form a team of 2 members and be registered on [Toph](https://toph.co). You can create an account [here](https://toph.co/register).
The contest is rated for all participants. There are also prizes for the students of Bangladeshi academic institutions:
- 1st place: Toph goodies and 250 GB Portable SSD
- 2nd and 3rd place: Toph goodies
The authors of the contest are [user:upobir,2022-04-09], [user:shefin.cse16,2022-04-09], [user:adnan_toky,2022-04-09], [user:thisIsMorningstar,2022-04-09], [user:rifatrraazz,2022-04-09], [user:Black_Be4rD,2022-04-09], [user:Short_Bit,2022-04-09] , [user:TarifEzaz,2022-04-09] and [user:Joty...
Invitation to Tough Duo, April 2022, Hello, Codeforces community!
188.
Helping the Tunisian National Team participate in the on-site IOI 2022 Hello Codeforces community,
[Click here to Donate](https://www.cha9a9a.tn/fund/detail/the-international-olympiad-in-informatics-ioi-329777)
My name is Amir Elarbi and I'm a member of the Tunisian IOI 2022 team along with Amine Ouesleti ([user:StrawHatWess,2022-07-05]), Hedi Chehaidar ([user:HediChehaidar,2022-07-05]) and Mohamed Ali Saidane ([user:MohamedAliSaidane,2022-07-05]).
I want to start by expressing my sincere gratitude for this opportunity. Representing Tunisia in one of the most important **international science Olympiads** has been a dream of mine ever since I started my journey with the national team.
Of course, **participating in the IOI wouldn't be the same without the on-site experience.**
Naturally, the goal of IOI goes beyond the competition itself and instead centers on the complete experience, which includes meeting others who share your interests, discovering new cultures, going on excursions, and much more.
As you may know, travel expenses to r...
Helping the Tunisian National Team participate in the on-site IOI 2022, Hello Codeforces community,
189.
Invitation to Replay of BUET Inter University Programming Contest 2022 Hello Codeforces,
We are glad to invite you to the online [Replay of BUET Inter University Programming Contest 2022](https://toph.co/c/buet-inter-university-2022-r), which will be hosted on [2 August 15:00 BST (UTC+6)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Replay+of+BUET+Inter+University+Programming+Contest+2022&iso=20220802T15&p1=73&ah=5). Duration of the contest is 5 hours. The main contest took place onsite this Friday organized by BUET. This is an ICPC style contest comprising of 10 problems of varying difficulties. The problemset can be thought as a 4-star gym set.
- Authors of this contest are [user:_Ash__,2022-08-01], [user:Anachor,2022-08-01], [user:Arg_007,2022-08-01], [user:imAnik,2022-08-01], [user:irri,2022-08-01], [user:MYNAMEISSHARIFUL,2022-08-01], [user:_no0B,2022-08-01], [user:rebornplusplus,2022-08-01], [user:upobir,2022-08-01] and me. It was additionally tested by [user:mahdi.hasnat,2022-08-01], [user:moidda,2022-08-01], [user:ramisa.alam,20...
Invitation to Replay of BUET Inter University Programming Contest 2022, Hello Codeforces,
190.
TJIOI 2022 Results <div style="text-align: center;"> <img src="/predownloaded/c4/33/c4336afbf01f8e8ebf4c5dfaa3d36f584fcc4057.png" width="50%" class="center"> </div>
Hello everyone!
We are super thankful for everyone who participated in the contest, and hope everyone enjoyed it! Here are the top finishers in the contest:
1. [user:timmyfeng,2022-06-12] — 8/8
2. [user:PurpleCrayon,2022-06-12] — 8/8
3. [user:thenymphsofdelphi,2022-06-12] — 7/8
4. [user:penguinhacker,2022-06-12] — 7/8
5. [user:BucketPotato,2022-06-12] — 7/8
Congrats to our winners, as well as everyone else who participated!
We would like to hold TJIOI again next year, and would greatly appreciate feedback on how we can improve. **Please fill out this survey if you have something to say about the contest: [Survey Link](https://forms.gle/JgWiMBFsoi7cD3H39)**
**Problem solutions will be posted shortly on the [TJIOI website](https://activities.tjhsst.edu/tjioi/).** The contest will remain public...
TJIOI 2022 Results, /c4336afbf01f8e8ebf4c5dfaa3d36f584fcc4057.png" width="50%" class="center"> Hello
everyone! We are super thankful for, Hello everyone!
191.
Mirror of the first stage of the National Computer Science Olympiad 2022-2023 Hello, Codeforces!
Congratulations to the 22 on the start of the new olympiad season! I wish your olympiad season a good one. I especially wish success to 11th graders, who will have to choose universities and apply for them this year.
I would like to invite you to participate in the mirror phase 1 of the National Olympiad in Informatics. The mirror will be held on codeforces.
This competition will be interesting rather for weaker participants (grey — turquoise on codeforces). The contest should not be difficult for experienced competitors.
The [contest_time:392106] will take place at [contest:392106].
- The competition is by IOI standards (partial points, test groups). You will be given 4 tasks for 5 hours
- **Unrated round**
- Use of any material published before the round is permitted.
Tasks together with me were proofread for errors and tested by [user:Irsanik,2022-10-04], [user:xyz.,2022-10-04], [user:I_love_my_Nadysha,2022-10-04], [user:ma_sad,2022-...
Mirror of the first stage of the National Computer Science Olympiad 2022-2023, Hello, Codeforces!
192.
Invitation USP Try-outs 2022 Hello, Codeforces!
On September 17 we held the University of São Paulo's Try-outs competition to select the teams that will represent the university in the Brazilian Regionals. On 1 October, 14:00 (UTC-3, São Paulo time) we will have a mirror competition in Codeforces Gym. This competition will be available afterward.
The link for the competition
https://codeforces.com/contestInvitation/b1511836e437c0205cee1f06890fddec6b30e82b
Competitors should follow ICPC Rules (i.e., 1 computer, teams of 3, etc...). We hope problems are challenging and interesting.
The authors of the contest are: Enrique [user:Byakko,2022-09-26] Junchaya, Giovanna [user:kobus,2022-09-26] Kobus, Jiang [user:kokosha,2022-09-26] Zhi, Lucas [user:lucas3h,2022-09-26] Harada, Pedro [user:pedroteosousa,2022-09-26] Souza, Renzo [user:renzo1805,2022-09-26] Gomez, Victor [user:VLamarca,2022-09-26] Lamarca, and myself.
We would like to thank the testers for their time and valuable feedback:
Bernardo ...
Invitation USP Try-outs 2022, Hello, Codeforces!
Announcement of 2022 USP Try-outs
193.
Educational Codeforces Round 119 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1620] [contest:1620] will start. **Please, note the unusual start time.**
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2021-12-17] Dalabaev, Vladimir [user:vovuh,2021-12-17] Petrov, Ivan...
Hello Codeforces! On [contest_time:1620] [contest:1620] will start. **Please,
note the unusual
Announcement of Educational Codeforces Round 119 (Rated for Div. 2)
194.
Invitation to Criterion 2022 Round 15 Hello, Codeforces community! <br>I'm glad to invite you to **Criterion 2022 Round 15** which will be held on [February 25, 2022, at 20:30 +0600 ](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Criterion+2022+Round+15&iso=20220225T2030&p1=73&ah=2&am=30) and will run for 2 hours 30 minutes.
The contest will take place at **Toph.co**
This contest is rated for all participants. You can register for the contest [here](https://toph.co/c/criterion-2021-round-15).
Problems of this contest were prepared and tested by [user:cryptid, 2020-07-04], [user:jackal_1586,2016-09-07], [user:adnan_toky,2021-07-03], [user:TarifEzaz,2016-01-17], [user:ishtupeed,2022-02-24], [user:ihumaunkabir,2016-07-01] and me.
Thanks to [user:TarifEzaz,2016-01-17] for his unconditional support and [user:hjr265,2021-04-08] for the best contest programming platform in Bangladesh.
We're inviting you all to participate in this contest. Hope you will enjoy the problem set. <br>There will be an editori...
Invitation to Criterion 2022 Round 15, Hello, Codeforces community!
I'm glad to invite you to **Criterion 2022 Round 15** which will
195.
The 1st Universal Cup. Stage 6: Taiwan Hello Codeforces! The 6th Stage of the 1st Universal Cup is coming. It will be held from Mar 4th to 5th.
The contest is based on an official ICPC Asia Pacific regional contest. It has been used in the 2022 ICPC Asia Taoyuan Regional Programming Contest, which was held on November 19, 2022 — November 21, 2022. Thanks to the judges and authors for preparing this great contest and sharing with us as a Universal Cup Stage.
As usual, we have three time windows for participating. You can participate in the contest in the following three time windows:
* Mar 4th 13:00 — 18:00 (UTC +8)
* Mar 4th 19:00 — 24:00 (UTC +8)
* Mar 5th 02:00 — 07:00 (UTC +8)
Please note that you can see two scoreboards in DOMjudge. The 'Local Scoreboard' shows the standings ONLY IN THE CURRENT TIME WINDOW. And the 'Combined Scoreboard' shows all participants, including the onsite participants, and the cup participants in the previous time windows.
Contest link: https://domjudge...
Hello Codeforces! The 6th Stage of the 1st Universal Cup is coming. It will be
held from Mar 4th to
196.
Codeforces Round #773 Hello, Codeforces!
We are glad to invite everyone to participate in [contest:1641] and [contest:1642], which will be held on [contest_time:1641]. **Notice the unusual time!** The round will be rated for both divisions. Each division will have **6** problems, and you will have **2 hours** to solve them. We recommend you read all the problems!
Tasks are based on [RocketOlymp](https://codeforces.com/blog/entry/99689), and were written and prepared by [user:__silaedr__,2022-02-21], [user:Allvik06,2022-02-21], [user:alegsandyr,2022-02-21], [user:ilyakrasnovv,2022-02-21], and [user:Isaf27,2022-02-21].
We are very thankful to
- [user:Isaf27,2022-02-21] for the great coordination, valuable advice, and patience.
- [user:Renatyss,2022-02-21], [user:stepanov.aa,2022-02-21], [user:_tryhard,2022-02-21], [user:Siberian,2022-02-21], [user:kirill.kligunov,2022-02-21], [user:arbuzick,2022-02-21] for the help during discussing and preparing problems.
- Our testers: [user:AlperenT,2022...
Hello, Codeforces! We are glad to invite everyone to participate in
[contest:1641] and [contest
Announcement of Codeforces Round 773 (Div. 1)
Announcement of Codeforces Round 773 (Div. 2)
197.
Educational Codeforces Round 140 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1767] [contest:1767] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-12-15] Dalabaev, Vladimir [user:vovuh,2022-12-15] Petrov, Ivan [user:BledDest,2022-12-15] Androsov, Mak...
Hello Codeforces! On [contest_time:1767] [contest:1767] will start. Series of
Educational
Announcement of Educational Codeforces Round 140 (Rated for Div. 2)
198.
Criterion 2022 Round 19 Invitation Hello Codeforces!
We are glad to invite everyone to participate in [Criterion 2022 Round 19](https://toph.co/c/criterion-2022-round-19), which will be held on [Friday, September 09, 2022 at 20:00(UTC+06:00)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Criterion+2022+Round+19&iso=20220909T20&p1=73&ah=2&am=30). You will be given **5 to 6 problems** and 2 hours and 30 minutes to solve them. The difficulty is expected to be similar to **Codeforces Div. 2 rounds**.
The problems were invented and reviewed by [user:rebornplusplus,2022-09-04], [user:ishtupeed,2022-09-04], [user:curly_braces,2022-09-04], [user:Atondro_Wahid,2022-09-04] and [user:gola,2022-09-04].
Thanks to [user:TarifEzaz,2022-09-04] for his unconditional support and [user:hjr265,2022-09-04] for the best contest programming platform in Bangladesh.
The contest will take place at [Toph](https://toph.co/). It will be [rated](https://help.toph.co/toph/rating-system/) for all the participants.
This conte...
Criterion 2022 Round 19 Invitation, Hello Codeforces!
199.
Codeforces Round 911 (Div. 2) Hello, Codeforces!
[user:Riblji_Keksic,2023-11-25] and I are glad to invite you to [contest:1900], which will start on [contest_time:1900]. You will be given **6** problems and **2** hours to solve them.
The round will be rated for participants of Division 2 with a rating lower than **2100**. Division 1 participants can participate unofficially.
All problems are invented and prepared by [user:Riblji_Keksic,2023-11-25] and me.
Special thanks go to [user:n0sk1ll,2023-11-25] and [user:TimDee,2023-11-25] for their great work during the testing process of the round.
And of course, I would love to thank the people who made this round possible:
- [user:pashka,2023-11-25] for his great coordination of the round!
- [user:IgorI,2023-11-25] for helping host the round!
- [user:Alexdat2000,2023-11-25] for helping translate the round!
- [user:prvocislo,2023-11-25], [user:wxhtzdy,2022-06-02], [user:valeriu,2023-11-25], [user:satyam343,2023-11-25], [user:n0sk1ll,2023-11-25...
Hello, Codeforces! [user:Riblji_Keksic,2023-11-25] and I are glad to invite you
to [contest:1900
Announcement of Codeforces Round 911 (Div. 2)
200.
ZJCPC2022 in the Gym! Hello! The 19th Zhejiang Provincial Collegiate Programming Contest has been uploaded to the Gym.
The link is [The 19th Zhejiang Provincial Collegiate Programming Contest](https://codeforces.com/gym/103687) .
This contest also serves as Contest 5, Div.A in this year's Moscow Pre-Finals Workshop 2022, with problems A, B, C, and G replaced. Note that the contest version in Gym is different from the original version used in ZJCPC. We deleted some of the data constraints in K to make the problem more fun.
Authors: [user:Claris,2022-05-09], [user:lxlxl,2022-05-09], [user:Suika_predator,2022-05-09], [user:oipotato,2022-05-09], [user:lwn_16,2022-05-09], [user:pb0207,2022-05-09]
Testers: [user:J.T.J.L.,2022-05-09], [user:chenjb,2022-05-09], [user:syvjjp416,2022-05-09], [user:Eden_CY,2022-05-09], [user:Sky_miner,2022-05-09], [user:Todobe,2022-05-09], [user:ILoveSetsuna,2022-05-09]
Official Scoreboard: [Official Scoreboard](https://board.xcpcio.com/provincial-contest/2022/zjcpc)
...
Hello! The 19th Zhejiang Provincial Collegiate Programming Contest has been
uploaded to the Gym
Announcement of The 19th Zhejiang Provincial Collegiate Programming Contest
201.
NITS Hacks 5.0 Inter College Coding Competition (Prizes worth 100K INR) Hello World!
Whether you're a beginner, a pro, or somewhere in between, Coding is always for everyone. No //comments about it, so let’s spice things up with a coding contest. **NITS HACKS 5.0** is back in association with **Coding Club NIT Silchar**, traversing you to an **Inter College Coding Competition** to develop your coding, real problem-solving abilities, and experience worth remembering.
The coding competition is open to all undergraduate programmers in India, although everyone is encouraged to participate in it. It will be split into preliminary and final rounds according to ICPC guidelines.
20 teams (Top 15 teams and 5 NITS teams) will be invited to participate in the on-site final round. These teams will be given travelling expenses (up to 1K INR per person), accommodation, local hospitality, and basic facilities by the institute.
**Rules:**
- A team of 2-3 members from the same college is required to participate in the contest.
- An eligible individual may ...
Hello World! Whether you're a beginner, a pro, or somewhere in between, Coding
is always for
202.
Codeforces Round 898 (Div. 4) Hello Codeforces!
[user:flamestorm,2023-09-20], [user:MikeMirzayanov,2022-07-11] and I want to invite you to [contest: 1873].
It starts on [contest_time: 1873].
The format of the event will be identical to Div. 3 rounds:
- 5-8 tasks;
- ICPC rules with a penalty of 10 minutes for an incorrect submission;
- 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
- after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
- by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).
We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.
Only _trusted participants of the fourth division_ wi...
Hello Codeforces! [user:flamestorm,2023-09-20], [user:MikeMirzayanov,2022
-07-11] and I want to
Announcement of Codeforces Round 898 (Div. 4)
203.
Invitation to Exun 2021-22 (Rated for Div.2 & Div.3) Hello, Codeforces!
We would like to invite you all to participate in the [Exun 2021-22 Competitive Programming](https://www.codechef.com/EXUN2021) contest this [Wednesday, 12th January 2022 from 8 PM to 11 PM IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Exun+2021-22+Competitive+Programming&iso=20220112T20&p1=176&ah=3).
The contest is rated for both division 2 and 3. Participants of division 1 are also encouraged to participate unofficially to get a chance for prizes. The contest, authored by me and [user:halemon123,2022-01-11], will feature 7 problems in all divisions.
I would like to thank:
- Our contest admin, [user:nishant403,2022-01-11], for providing invaluable feedback on the problem set.
- [user:knightron00,2022-01-11] for helping with preparation.
- [user:iscsi,2022-01-11] for testing.
- [user:aujasvit_datta,2022-01-11], [user:vedantsingh1,2022-01-11], [user:DumbbAlgo,2022-01-11] and
[user:halemon123,2022-01-11] for helping with testing and ...
Hello, Codeforces! We would like to invite you all to participate in the [Exun
2021-22
204.
CF-Predictor news Hello all!
I have some news to share about CF-Predictor (a service that allows you to view rating changes before official results). This extension [was launched](https://codeforces.com/blog/entry/50411) almost 6 years ago. Number of users has grwon from a couple hundreds to nearly 50k! I'm very proud that this service is used by so many people!
One of the cool features of mine extension is that it is friendly to codeforces API :) All the request to codeforces are sent from just one backend server. Therefore, users don't overload codeforces with extra API calls.
I was using Heroku as a cloud provider to run my servers. Unfortunately, they are closing their free accounts on Nov 28th. So, I decided to take down my servers on heroku. Thus, starting from 2022-11-27 [cf-predictor-frontend.herokuapp.com](https://cf-predictor-frontend.herokuapp.com) and [cf-predictor.herokuapp.com](https://cf-predictor.herokuapp.com) will **not** work.
On a bright side, I though that upsetting 50k ...
Hello all! I have some news to share about CF-Predictor (a service that allows
you to view
205.
Historic moment Hello, today in CodeTON round #3, one of the most epic moments in cf history has happened. It's about [user:tourist,2022-11-06].
Did he finally cross 4000 rating? No.
Today, he got owned by his archenemy, python gigachad [user:conqueror_of_tourist,2022-11-06].
Congratulations to [user:conqueror_of_tourist,2022-11-06]. Good job, king!
Hello, today in CodeTON round #3, one of the most epic moments in cf history
has happened. It's
206.
A look at Competitive Programming post-hibernation Hello friends!
As I've recollected in a previous [post](https://codeforces.com/blog/entry/97566), I am an old competitor who hadn't really participated since ~2014, and recently got a bout of nostalgia to return to Competitive Programming. So, I did a couple Topcoder SRMs, suffered through some SNWS rounds, participated in [three regional 5hr competitions](https://contest.yandex.ru/3QF2021) on three consecutive days, and dozed off at every Codeforces contest I tried to wake up for.
A lot of things are still the same as 8 years ago: [user:tourist,2022-01-26] is still at the top, grey coders still ask for how many minutes to solve a problem before reading the editorial, Russian university teams [continue winning](https://icpc.global/worldfinals/results) ACM ICPC, and Snarknews never gives up on his alternate competition formats. But in this post, I want to focus on the new patterns that emerged since my last time around.
#### #1: Codeforces rounds timing
Did you know that t...
Hello friends! As I've recollected in a previous
[post](https://codeforces.com/blog/entry/97566
207.
Codeforces Round #840 (Div. 2) and Enigma 2022 — Cybros LNMIIT Hello, Codeforces!
Cybros, the competitive programming club of LNMIIT Jaipur, is happy to invite you to participate in [contest:1763] which will be held on [contest_time:1763].
[<img src="https://iili.io/Hx3h6s1.png" width="250px" height="300px" align="middle" marginLeft="120px" style="float: right;"/>]()
You will be given **6 problems** and **2 hours** to solve them. The round will be rated for participants with rating **strictly less than 2100**. Division 1 participants can also participate unofficially in the round.
The problems were prepared by me, [user:DreadArceus,2022-12-17], [user:nobita1729,2022-12-17], [user:warks,2022-12-17], [user:.utk.,2022-12-17], and [user:gupta6007,2022-12-17]. We would like to thank:
- [user:Aleks5d,2022-12-17] for coordinating the round and translating the statements into Russian,
- [user:svince,2022-12-17], [user:tankman890,2022-12-17], [user:SoCloseButStillSoFar,2022-12-17], [user:shiviDON,2022-12-17], [user:abhigyan10,2022-12-17...
Codeforces Round #840 (Div. 2) and Enigma 2022 — Cybros LNMIIT, Hello, Codeforces!
Announcement of Codeforces Round 840 (Div. 2) and Enigma 2022 - Cybros LNMIIT
208.
My long and lonely way to specialist I started competitive programming in July 2021. After two and half years, that's a long time, I just reached specialist. After every wins and losses, I always thought my coder life is like a road without any ends. I wanted to give up more than one time, but the charm of competitive programming always kept me going, on the long and lonely way.
In the first year of competitive programming, I just learned binary search, greedy and some other algorithms. But I couldn't use them proficiently. I even failed in the first round of CSP-Junior (An primary competition in China). Although China was strong in competitive programming, there were only three coders in my school, and two of them were retired in the 9th grade. I felt lonely at that time because no one could teach me to improve except my programming teacher (my friends did't know anything about programming at all) until I found Codeforces.
Under the guidance of Luogu users, I created my CF account in October 2022. And I took part i...
Under the guidance of Luogu users, I created my CF account in October 2022. And
I took part in my
209.
[Tutorial] Polygon.Codeforces Tutorial — A Guide to Problem Preparation [Part 1] Hello Codeforces!
I am a author of [a Codeforces contest](https://codeforces.com/blog/entry/98385), and recently, I became a coordinator for [a Codeforces round](https://codeforces.com/blog/entry/100368) as well. After those two rounds, there are a some problems arise when preparing a problem. Thinking about the solutions to these problems, I decided to gather them into a blog series. Hopefully, this series will be helpful to the future problem setters, or people who want to create problems in general.
I have finished the first part of this series. It aims to introduce the Polygon platform to the new problem setters, and guide them through the basic steps on creating a new problem from scratch. In the post, I have explained the concepts and practices that a problem setter need to know in order to use Polygon to prepare problems.
Here is the link to the blog post: [Polygon.Codeforces Tutorial — A Guide to Problem Preparation [Part 1]](https://quangloc99.github.io/posts/po...
Hello Codeforces! I am a author of [a Codeforces
contest](https://codeforces.com/blog/entry
210.
Codeforces Round #910 (Div. 2) Hello, Codeforces!
[user:ELDRVD,2023-11-15] and I are glad to invite you to [contest:1898], which will start on [contest_time:1898]. You will be given **6** problems and **2** hours to solve them.
The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially.
All problems are invented and prepared by [user:ELDRVD,2023-11-15] and me. Special thanks go to [user:Sofija06,2023-11-15] and [user:NemanjaSo2005,2023-12-04], our two most dedicated testers. We would also like to honor:
- [user:prvocislo,2023-11-15], [user:wuhudsm,2023-11-15], [user:Marckess,2023-11-15], [user:MateoCV,2023-11-15], [user:Wibo,2023-11-15], [user:curly_braces,2023-11-15], [user:LucaLucaM,2023-11-15], [user:null0124,2023-11-15], [user:OAleksa,2023-11-15], [user:AlphaMale06,2023-11-15], [user:FireFrog418,2023-11-15], and [user:sahaun,2023-11-15] for testing this round and providing valuable feedback!
- [user:IgorI,2023-11-15] f...
Hello, Codeforces! [user:ELDRVD,2023-11-15] and I are glad to invite you to
[contest:1898
Announcement of Codeforces Round 910 (Div. 2)
211.
Codeforces blocking my account for a fake cheating accuse Requested to publish from [user:Basilhijaz,2023-10-09]:
"
Hello, I am [user:Basilhijaz,2023-10-09]. I participated in lots of Codeforces rounds and the last one I did was [contest:1879]. Unfortunately, I was trying to login to my account today and got the message "User is disabled by administrators". I checked my email and it looks like I was accused of cheating in that specific round. Apparently my Submission on Problem B [submission:224888371] is so close to [user:LetsPractice,2023-10-09]'s Submission [submission:224901176].
This problem we both got accused of copying from each other is B in an Educational round which means solutions can get actually really close and if you notice the solutions are so short which increases the probability of matching.
Previous Accuses of Cheating Attempts (Problem, My Submission, Similar Submission/s)(problem classification):
- ([problem:1462D], [submission:101301240], [submission:101299306]) (D div3).
- ([problem:1670A], [submi...
Requested to publish from [user:Basilhijaz,2023-10-09]: " Hello, I am
[user:Basilhijaz,2023
212.
[Suggest] Reduce cheating Hello contestants and Mr. [user:MikeMirzayanov,2022-11-25], 👋
We all see that cheating is spreading so much in the contests, there are a lot of people complaining that they didn't cheat in the contest the solution of them are skipped due to the similarity between their solution and another solution, I think that happened because `Div2, Div1, and Global` the system is we get a pretest passed and can lock our problem and open our room and see other contestants solutions in the room, so the cheater can send the solutions to other people and the got skipped their solution without cheating.
I know that is the system of the site, I don't say that codeforces must change it, I try to pass this information on to Mr. [user:MikeMirzayanov,2022-11-25] to help to find any solution to it.
I don't know why they use this type of checking, not like `Div3, Div4, and EDU` and making hacking phase 12 hours, so I will not ask for that because Mr. Mike surely has his reasons.
But let's g...
Hello contestants and Mr. [user:MikeMirzayanov,2022-11-25], 👋
213.
The 1st Universal Cup. Stage 8: Slovenia Hello Codeforces! The 8th Stage of the 1st Universal Cup is coming. It will be held from Mar 18th to 19th.
The contest is based on an official ICPC European regional contest. It has been used in the 2022 ICPC Central Europe Regional Programming Contest, which was held on November 25, 2022 — November 27, 2022 in Ljubljana, Slovenia. Please, don't participate if you are already familiar with the problem set.
Thanks to the authors of the problem set: [user:thocevar,2023-03-16], [user:koci,2023-03-16], [user:jureslak,2023-03-16], [user:jklepec,2023-03-16], [user:nbasic,2023-03-16], [user:MKoding,2023-03-17] and others.
As usual, there are three time windows in which you can participate in the contest:
* [Mar 18th 13:00 — 18:00 (UTC +8)](https://www.timeanddate.com/worldclock/fixedtime.html?msg=The+1st+Universal+Cup.+Stage+8%3A+Slovenia+%28time+slot+1%29&iso=20230318T13&p1=3910&ah=5)
* [Mar 18th 19:00 — 24:00 (UTC +8)](https://www.timeanddate.com/worldclock/f...
Hello Codeforces! The 8th Stage of the 1st Universal Cup is coming. It will be
held from Mar 18th
214.
New Year's round... Hello, Codeforces!
------------------
So an unforgettable, rather difficult $2022$ year is coming to the end... However, it is about to be replaced by the long-awaited $2023$, which, I hope, will bring a lot of good both to you, people, and Codeforces...
I, [user:Ilya_Is2022,2022-12-24], am glad to invite you to [contest: 417995] , which will take place already [contest_time: 417995] . Everyone will be able to take part in this round, regardless of the division :)
In the round, you will be expected **5 — 8** tasks on New Year's theme (´｡• ᵕ •｡`). The round will take only **2** hour and **5** minutes, so I **would** **like** you to solve as many problems as possible! The competition will be held in the **ICPC** format, and testing of your solutions will be carried out on the full set of tests provided for the task (⌒‿⌒).
I would like to thank:
- [user:nekstas,2022-12-24] for help in making tasks.
- [user:Alexfil,2022-12-24], [user:Anton_Wars,2022-12-26] for tes...
Hello, Codeforces! ------------------ So an unforgettable, rather difficult $
2022$ year is
215.
Invitation to Code-MAT'22 Hello codeforces!!
**Mathematics and Computing Society (MACS) IIT BHU** is glad to invite you to our programming event **Code-MAT'22**. The contest will take place on Codechef [5th November, 17:30 IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Code-MAT%2722&iso=20221105T1730&p1=1045&ah=2). You will be given 2 hours to solve 6-8 problems of varying difficulty which is bound to keep you on your toes.
**Contest link** : https://www.codechef.com/CMAT2022
The problem set has been authored and prepared by [user:pd_codes,2022-11-03], [user:brahma_afk,2022-11-03], [user:Gokussjz,2022-11-03], [user:wasted-light,2022-11-03], [user:world_classic,2022-11-03], [user:stunner45,2022-11-03], [user:Akshat_bhalawat,2022-11-03] and me.
We would like to thank [user:ayu_19,2022-11-03], [user:akshat.shah.mat20,2022-11-03] and [user:Harshjain4001,2022-11-03] for helping with the problem preparation.
The problems have been tested by [user:saatvik10,2022-11-03], [user:Ayrt_Samura...
Hello codeforces!! **Mathematics and Computing Society (MACS) IIT BHU** is glad
to invite you to
216.
[Gym] Invitation to Abakoda 2022 Beginner-Friendly Long Contest Hello all! I have another contest to share with you all.
Abakoda was an initiative by NOI.PH (the Philippines' olympiad) to run a series of beginner-friendly weekly contests, which ultimately culminated in a long contest. Contestants were given a little under 10 days to solve 13 problems. We have decided to share these problems with the general Codeforces community.
I feel very strongly that good beginner contests are required in order to lower the barrier to competitive programming. And I'm quite proud of the set that I ended up writing! The problems should be approachable for beginners... but that said, I think there are a handful of problems that more experienced contestants might find interesting anyway :)
The contest link is here: https://codeforces.com/gym/104146
Enjoy!
Thanks to [user:verngutz,2023-01-19] for helping me set one of the problems, and thanks to [user:ongyiumark,2023-01-19] and [user:lyreloi,2023-01-19] and [user:cerebi,2023-01-19] for helping me w...
[Gym] Invitation to Abakoda 2022 Beginner-Friendly Long Contest, Hello all! I have another contest to share with you all.
217.
Invitation to Toph Criterion 2022 Round 17 Hello good people,
I am delighted to invite you all to the [Toph Criterion 2022 Round 17](https://toph.co/c/criterion-2022-round-17)!
To participate you have be registered on [Toph](https://toph.co/).
Toph is a leading competitive programming platform in Bangladesh hosting various programming contests.
The author of the contest are [user:upobir,2022-06-23], [user:shefin.cse16,2022-06-23], [user:rifatrraazz,2022-06-23], [user:adnan_toky,2022-06-23], [user:thisIsMorningstar,2022-06-23], [user:Short_Bit,2022-06-23], [user:Black_Be4rD,2022-06-23] and [user:TarifEzaz,2022-06-23].
Special thanks to [user:TarifEzaz,2022-06-23] for coordinating this contest and [user:hjr265,2022-06-23] for the **Toph** platform.
You will be given **6-7** problems. The contest will follow **standard ICPC rules**.
We've tried to create very engaging problems and robust datasets for this contest. We hope you will enjoy the problem set.
Also, there will be an editorial shortly after the contes...
Invitation to Toph Criterion 2022 Round 17, Hello good people, I am delighted to invite you all to the [Toph Criterion 2022
Round 17](https
218.
Personal olympiad for 6th — 9th grades Hello, Codeforces!
**Due to Educational round, olympiad will start at 10 april**
**The mirror will start tomorrow, 11 of april, at 16:35**
**Registration closed**
**Final results were published. Diplomas are out**
At [contest_time:368205] will be held [contest:368205]. Everyone can participate in the mirror of the contest. If you are a student of 6th — 9th forms, then fill the form to participate officially.
Contest will follow the IOI rules (test groups, partial solutions). You will be given from 5 to 7 tasks for 3 hours. Standings will be shown after ending of the round.
Thanks [user:kefaa,2022-03-30] for amazing coordination of the round.
Tasks are checked and tested by [user:oleh1421,2022-03-30], [user:gepardo,2022-03-30], [user:kartel,2022-03-30], [user:xyz.,2022-03-30], [user:Wind_eagle,2022-03-30], [user:OpPo,2022-04-02], [user:Vlad.cpp,2022-03-30], [<font style="color:#111111"> **sadfun**</font>](https://sort-me.org/profile/1), [user:Irpacci,2022-0...
Hello, Codeforces! **Due to Educational round, olympiad will start at 10
april** **The mirror
219.
Replay of Battle of Brains 2022, University of Dhaka Hello, Codeforces!
We're excited to invite you to [Replay of Battle of Brains 2022, University of Dhaka](https://codeforces.com/contestInvitation/be6b5daea285c235307d55725f9b80340f4d5923), a yearly intra-university programming contest between the freshers and sophomores of the **University of Dhaka**. The problemset will have difficulty in between Division 2 and Division 3. Get ready for some brain-teasing fun!
- Number of Problems: **10**
- Date and Time: [contest_time:104679]
- Contest format: Individual
- Contest Duration: **4 hours**
The problems are prepared and tested by: [user:aymanrasheed7,2023-10-06], [user:_timelord,2023-10-06], [user:Turnogen,2023-10-06], [user:frosted,2023-10-06], [user:GandhiG,2023-10-06], Wakilur Islam, [user:serotonin,2023-10-06], [user:_skb_,2023-10-06], [user:Alpha_Q,2023-10-06], [user:DrSwad,2023-10-06], [user:fahimcp495,2023-10-06], [user:ZED_,2023-10-06], [user:akifpathan,2023-10-06].
See you on the ranklist!
Update: [Editoria...
Replay of Battle of Brains 2022, University of Dhaka, Hello, Codeforces!
Announcement of Replay of Battle of Brains 2022, University of Dhaka
220.
Educational Codeforces Round 133 [Rated for Div. 2] Hello Codeforces!
On [contest_time:1716] [contest:1716] will start.
Series of Educational Rounds continue being held as [Harbour.Space University](https://harbour.space/) initiative! You can read the details about the cooperation between [Harbour.Space University](https://harbour.space/) and Codeforces in the <a href="http://codeforces.com/blog/entry/51208">blog post</a>.
This round will be **rated for the participants with rating lower than 2100**. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.
You will be given **6 or 7 problems** and **2 hours** to solve them.
The problems were invented and prepared by Adilbek [user:adedalic,2022-08-03] Dalabaev, Vladimir [user:vovuh,2022-08-03] Petrov, Ivan [user:BledDest,2022-08-03] Androsov, Mak...
Hello Codeforces! On [contest_time:1716] [contest:1716] will start. Series of
Educational
Announcement of Educational Codeforces Round 133 (Rated for Div. 2)
221.
[PRIZES] Invitation to Yet Another Contest 6 Hello Codeforces!
Yet another time, this is yet another blog post, with yet another announcement regarding yet another invitation to [Yet Another Contest 6](https://dmoj.ca/contest/yac6), which will be hosted by DMOJ from [Friday, December 23 00:00 EST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Yet%20Another%20Contest%206&iso=2022-12-23T05:00:00) to [Tuesday, December 27 00:00 EST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Yet%20Another%20Contest%206&iso=2022-12-27T05:00:00). Participants will be given a 3-hour window to solve 6 problems with varying difficulty, with the difficulty being approximately Div. 2 level. **Unlike the previous YAC, this contest will be rated for all users with ratings less than 2800.**
Also, this contest has prizes, for both rated and unrated users, one of which is randomly selected. These prizes include Discord Nitro and steam codes for Sid Meier’s Civilization VI. See the [contest page](https://dmoj.ca/contest/yac6) for...
Hello Codeforces! Yet another time, this is yet another blog post, with yet
another announcement
222.
DMOPC '22 September Contest Hello, Codeforces!
We are excited to announce that the first DMOJ Monthly Open Programming Competition (DMOPC) of the 2022 season has started today!
[](https://dmoj.ca/contest/dmopc22c1)
The contest takes place on Friday, September 30th, from [midnight EDT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=DMOPC+%2722+September+Contest&iso=2022-09-30T04%3A00%3A00%2B00%3A00), lasting 4 days until [midnight EDT](https://www.timeanddate.com/worldclock/fixedtime.html?msg=DMOPC+%2722+September+Contest&iso=2022-10-04T04%3A00%3A00%2B00%3A00) on Tuesday, October 4th. Within this 4 day window, you will have **3 hours** to complete the contest. For more details on the contest format, please visit the [contest page](https://dmoj.ca/contest/dmopc22c1).
The DMOPC consists of **6 problems** with a wide range of difficulties, and you can get partial marks for partial solutions in the form of **subtasks**. If you cannot sol...
Hello, Codeforces! We are excited to announce that the first DMOJ Monthly Open
Programming
223.
APIO 2022 Open Contest Invitation Hello Codeforces,
APIO 2022 is going to take place in a few days. As usual, we invite everyone to join the open contest this year. It'll have the same problem set as APIO 2022 and will be held using CMS the same system the official contest will use.
The contest window will start from [Monday, 30 May 2022 — 00:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?iso=20220530T00) till [Tuesday, 31 May 2022 — 00:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?iso=20220531T00). The contest duration is 5 hours and each user can participate any time within that window.
You can register using the following link: [link](https://forms.gle/bZ3taKzPkJDh6pz4A)
**UPD: Registeration for the open contest will close at [Monday, 29 May 2022 — 00:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?iso=20220529T00) in about 7 hours.**
Regards,
APIO 2022 Scientific Committee.
APIO 2022 Open Contest Invitation, Hello Codeforces, APIO 2022 is going to take place in a few days. As usual, we
invite everyone
224.
UFDS Mentoring 2024 Hello everyone,
We hope you are doing well. We are here to announce that we are now opening sign-ups for UFDS 2024. The program is designed to train students for [ZCO, INOI and IOITC](https://www.iarcs.org.in/inoi/).
The following students (and mentors) were all a part of UFDS 2023:
- All 4 students selected for IOI.
- All 6 students who represented India at the APIO. They won 2 gold and 2 bronze medals.
- 1 student reached IOI 2023 with just 10 months of Competitive Programming experience.
- 9 out of the 10 students who got gold in INOI.
The server also surrounds you with like-minded people, so everyone can help each other.
If you join the program, we will help you by:
- Setting contests to improve your skills
- Compiling useful practice problem sets to introduce you to a variety of different techniques
- Selecting problems to practice with
- Providing hints to solve problems in practice
- Discussing problems after a contest
- Recommending similar problems (...
Hello everyone, We hope you are doing well. We are here to announce that we are
now opening sign
225.
Training Round #1 (2022-2023) Hello!
~~~~~
cout<<"Hello!";
~~~~~
We are proud to finally invite you to participate in Codeforces Training Round #1[Round link access after registering down](http://codeforces.com/contests/404622) which will start on Monday, October 31th, 2022, 14:35 UTC You will be given 6 problems and 2.5 hours to solve them. We greatly recommend to read all the problems.
[See results here](https://codeforces.com/spectator/ranklist/cbdc2dab27e7b625d75b5322b7d87e2e)
Joining problem setting panel are:
Setters: [user:andrei_iorgulescu,2022-10-18] (Andrei Iorgulescu), [user:andreifilimon,2022-10-18] (Andrei Popescu Filimon)
A share will help us having more participants in this round!
Good luck & have fun & the third part!
**UPD1: Winners!**
1. [user:MateiKing80,2022-10-31]
2. [user:ericutz,2022-10-31]
3. [user:CezarForces,2022-10-31]
4. [user:tone_alexandru,2022-10-31]
5. [user:Tedic,2022-10-31]
6. [user:AdelinaVioleta,2022-10-31]
7. [user:rebeeg,2022...
Training Round #1 (2022-2023), Hello! ~~~~~ cout<<"Hello!"; ~~~~~ We are proud to finally invite you to
participate in
226.
[Tutorial] Product Trick Hello everyone,<br>
in this tutorial we will see a trick that can be useful in combinatorics and/or DP tasks. In particular, you can use it when the statement says something similar to "the score of an array is the product of its elements, find the sum of the scores over all the possible arrays".
Prerequisites: basic combinatorics and DP
The trick
------------------
The trick is very simple.
"The score of an array $a$ is $\prod_{i=1}^n a_i$" can be rephrased as "if there are $n$ boxes, and the $i$-th box contains $a_i$ distinguishable balls, the score of $a$ is equal to the number of ways to color a ball for each box".
This is quite obvious, but it can be extremely powerful. Let's see some problems that are trivialized by this trick.
[Dwango Programming Contest 6th, problem C](https://atcoder.jp/contests/dwacon6th-prelims/tasks/dwacon6th_prelims_c) (rating: 2618)
------------------
<spoiler summary="Hint 1">
You have to output the sum of the happiness over all po...
Hello everyone,
in this tutorial we will see a trick that can be useful in combinatorics and
227.
Invitation to Alohomora [Editorial Update]        <img src="https://s3.amazonaws.com/discourseproduction/original/3X/e/2/e2202389add9196506e4e92f814c5ef6c336dd27.jpeg" width = "500" />
Hello Codeforces!
_From the infinite possibilities of the multiverse, Spider Man has found out the one and only one way to save the world from collapsing. You being his comrade must assist him in saving the world in the best possible way !_
[RECursion](https://recursionnitd.in/) presents you [**Alohomora**](https://www.codechef.com/ALMR2022) — an ICPC-styled team coding contest where you would have to assist Spiderman in teams of **at most 3** people against an unwanted disaster.
The contest will start on [April 10 2022 at 9:00 PM IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Alohomora&iso=20220410T21&p1=1993&ah=2&am=30). Contest duration is 2 hours 30 minutes.
We are also giving away prizes for top performing teams of our contest as follows :
* Cash prize of **Rs 5000** a...
/original/3X/e/2/e2202389add9196506e4e92f814c5ef6c336dd27.jpeg" width = "500" />
Hello Codeforces
228.
Moldova IOI and EGOI teams Hello codeforces. As you could probably see in my previous posts, recently team selections ended in our country.
Now the teams for IOI/BOI and EGOI are defined:
IOI/BOI team:
[user:SlavicG,2022-05-04] [user:KrowSavcik,2022-05-04] [user:RedFlea,2022-05-04] [user:_Vanilla_,2022-01-30]
EGOI team:
[user:SlavicG,2020-04-03] [user:KrowSavcik,2021-01-04] [user:RedFlea,2020-11-01] [user:_Vanilla_,2022-01-30]
Hello codeforces. As you could probably see in my previous posts, recently team
selections ended in
229.
Invitation to CodeCracker 2022 **Hello Codeforces,**
**Team Aavishkar, NIT Durgapur** invites you to participate in the 6th edition of **CodeCracker, the coding competition of our annual Tech Fest, Aarohan '22**.
The contest will be an **ACM style** contest and will consist of **5 problems**.
- **Contest Link** — [CodeCracker 2022](https://codecracker.in/)
- **Start time** — [05 March 2022 22:30:00 IST](https://www.timeanddate.com/countdown/generic?iso=20220305T2230&p0=54&msg=CodeCracker+2022&font=cursive)
- **Duration** — 2 hours
**Prizes:** Cash prizes up to INR 15,000 will be distributed among the top contestants (Globally.)
In order to be eligible for prizes, you need to register [here](https://codecracker.in/)
The contest will be held on our very own online judge — [CodeCracker](https://codecracker.in/), which is completely open-source.
The site is live, so you may register and check out the platform using a soon to be live test contest. Comment here if you found any bug, have queries, or h...
Invitation to CodeCracker 2022, **Hello Codeforces,**
230.
Invitation to the contest Hello, Codeforces! We with [user:sdyakonov,2022-05-13] invite you to [contest:382218], which will take place at [contest_time:382218]. We invite everyone. The contest will be **not** rated. The competition will be held according to ICPC rules. There will be 11 tasks in total. The contest will be of most interest to experts or below. But we invite purple and above to participate. The contest will be in [this group](https://codeforces.com/group/cBrcov20zj/blog).
Tasks have been prepared by [user:sdyakonov,2022-05-12], [user:kirill020708,2022-05-12], [user:onlytrall,2022-05-12]
**Statements will be in English and Russian**
Thanks for preparing the contest to the following people:
1. Testers: [user:valerikk,2022-05-17], [user:sokol080808,2022-05-12], [user:adepteXiao,2022-05-12], [user:makrav.io,2022-05-12], [user:onlytrall,2022-05-12], [user:Splatjov,2022-05-12], [user:Gamer_kotik,2022-05-12], [user:MrDlop,2022-05-12], [user:akatevsw,2022-05-12 ].
2. Special thanks to [user...
Hello, Codeforces! We with [user:sdyakonov,2022-05-13] invite you to
[contest:382218], which will
231.
The 2nd Universal Cup. Stage 13: Shenyang Hello! I'm happy to announce The 2nd Universal Cup. Stage 13: Shenyang, which will be held on December 9th, 2023.
This contest is an official ICPC Regional Contest — The 2023 ICPC Asia Shenyang Regional Contest. It is the 9th consecutive year that Northeastern University has hosted the ICPC Asia Shenyang Regional Contest. Great thanks to the host school for preparing the Regional, and the hard work done by all staff and volunteers for this contest.
<img src="/predownloaded/24/83/2483ceaf571339751e32ed2e5401c5d08bd6db18.jpg" width="35%" height="35%" /> <img src="/predownloaded/e3/fb/e3fb46fa993b6b46dadb89ee7b0aac495abb5d29.jpg" width="27%" height="27%" /> <img src="/predownloaded/00/8c/008c2d13555c6d9b32427762cc02559356f52e08.jpg" width="35%" height="35%" />
The authors for preparing the contests: [user:Sulfox,2023-12-06], [user:quailty,2023-12-06], [user:lzr_010506,2023-12-06], [user:calabash_boy,2023-12-06], [user:Gromah,2023-12-06].
The testers for their valuable advice: ...
Hello! I'm happy to announce The 2nd Universal Cup. Stage 13: Shenyang, which
will be held on
232.
Hi neoyg! Hello, community!
Recently, not my friend [user:neoyg,2022-10-03] posted a blog about with a Title-
**IMP: Sharing screenshots of code from the room during contests**
where he posted that
_I discovered that people are now sharing other people's codes who are in their room since, after locking, we can see other people's solutions. Those screenshots were circulated in Discord groups._
Cool, he helped the community.
But wait, how did he know about the discord community since he posted a screenshot of a message from the discord group? Was he a part of the group?
Secondly, I saw his recent submissions from CF Round #824 and found out that his submissions were similar to those of the leaked ones.
[Proof- Compare his submissions for Problem C and D from the solution in this link](https://codeforces.com/blog/entry/107556#comment-959113)
One interesting question, how can someone code Problem D in python when he always coded in CPP?
His only submission in Python/Pypy is y...
Hello, community! Recently, not my friend [user:neoyg,2022-10-03] posted a blog
about with a
233.
FMI No Stress 11 Hello everyone,
I would like to announce a new edition of FMI No Stress.
FMI No Stress contest is organized by members of the Faculty of Mathematics and Computer Science at the University of Bucharest.
This year we hold the 11th edition of the competition, and the first year in which we host the contest on Codeforces.
Link: https://codeforces.com/group/GBHgtTKxyY/contests (join here as participant).
The round will start on [Sunday, October 30, 2022 at 10:00](https://www.timeanddate.com/worldclock/fixedtime.html?day=30&month=10&year=2022&hour=11&min=0&sec=0&p1=166) and will follow IOI rules.
You will be given 13-15 problems and 5 hours to solve them.
Students of the Faculty of Mathematics and Informatics can participate onsite in Pompeiu, Google, Laboratory 221 rooms. The top first year students that participate onsite will receive prizes.
Top 10 last year highschool students (12th grade) will be automatically qualified for the final round of MateInfoUB.
The p...
Hello everyone, I would like to announce a new edition of FMI No Stress. FMI No
Stress
Announcement of FMI No Stress 11
234.
The 2nd Universal Cup. Stage 23: Shanghai (ICPC Asia EC Finals 2023) Hello everyone!
We are thrilled to invite you to **The 2nd Universal Cup, Stage 23: Shanghai**, taking place on February 17th, 2024.
This stage is based on The 2023 ICPC Asia East Continent Final Contest, which is the last contest in the Asia EC Region in this season. 280 official teams participated in the onsite contest competed for the last WF slots of the season.
I would like to thank all task writers for their efforts on preparing the contest. They are [user:dXqwq,2024-02-16], [user:jqdai0815,2024-02-16], [user:Kubic,2024-02-16], [user:littlelittlehorse,2024-02-16], [user:MagicalFlower,2024-02-16], [user:Qingyu,2024-02-16], [user:QuietBeautifulThoughts,2024-02-16], [user:unputdownable,2024-02-16], and [user:xyz2606,2024-02-16].
Also a big thank you to all the people who tested the contest and gave their valuable advice: [user:__ZMF__,2024-02-16], [user:antontrygubO_o,2024-02-16], [user:chenjb,2...
Hello everyone! We are thrilled to invite you to **The 2nd Universal Cup, Stage
23: Shanghai
235.
Invitation for IISc AlgoRush (Cash Prizes worth ₹50K) Hello Codeforces!
We are glad to introduce **IISc AlgoRush**, an ACM ICPC-style programming event as a part of [Rhapsody'22 (IISc's Mega Annual Fest)](https://rhapsodyiisc.com/)
<spoiler summary="Contest Poster">
</spoiler>
IISc AlgoRush consists of a preliminary online round cooked in the kitchen of CodeChef, followed by an on-site round to be held at the IISc campus with **exciting cash prizes worth Rs 50K.**
The preliminary online round will be held on [28th June 2022, 10:30 PM — 29th June 12:45 AM IST](https://www.timeanddate.com/worldclock/fixedtime.html?msg=IISc+AlgoRush&iso=20220628T2230&p1=438&ah=2&am=15).
The top 15 non-IISc teams and top 10 IISc teams will be invited for the on-site final round to be held on 8th July.
A team can have at most two members.
*To be eligible for the final round, the participants must be students of the same Institute/School (recent 2022 batch pass-ou...
Hello Codeforces! We are glad to introduce **IISc AlgoRush**, an ACM ICPC-style
programming
236.
2021-2022 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC Rules, Teams Preferred) Hello.
In the meantime, the onsite event has already begun. You can follow the results at the link https://nerc.itmo.ru/archive/2021/standings.html (refrain from viewing if you want to plan to write a mirror and want the conditions as close as possible to the participants in the competition).
There is great news. This year it was possible to get together without any online participation. Teams write from one computer! Good old ICPC.
And I suggest you join the online mirror. It is designed for team participation by those who have passed the qualifying competitions. Ready to try? Use the link: [contest:1666].
Good luck!
2021-2022 ICPC, NERC, Northern Eurasia Onsite (Unrated, Online Mirror, ICPC
Rules, Teams Preferred), Hello.
Codeforces (c) Copyright 2010-2024 Mike Mirzayanov
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