#### UPD: (28 April, 2022)
→ Pay attention
→ Top rated
| # | User | Rating |
|---|---|---|
| 1 | ecnerwala | 3649 |
| 2 | Benq | 3581 |
| 3 | orzdevinwang | 3570 |
| 4 | Geothermal | 3569 |
| 4 | cnnfls_csy | 3569 |
| 6 | tourist | 3565 |
| 7 | maroonrk | 3531 |
| 8 | Radewoosh | 3521 |
| 9 | Um_nik | 3482 |
| 10 | jiangly | 3468 |
→ Top contributors
| # | User | Contrib. |
|---|---|---|
| 1 | maomao90 | 174 |
| 2 | awoo | 164 |
| 3 | adamant | 162 |
| 4 | TheScrasse | 159 |
| 5 | nor | 158 |
| 6 | maroonrk | 156 |
| 7 | -is-this-fft- | 151 |
| 8 | SecondThread | 147 |
| 9 | orz | 146 |
| 10 | pajenegod | 145 |
→ Find user
→ Recent actions
You can use several words in query to find by all of them at the same time. In addition, if you are lucky search understands word forms and some synonyms. It supports search by title and author. Examples:
305— search for 305, most probably it will find blogs about the Round 305andrew stankevich contests— search for words "andrew", "stankevich" and "contests" at the same timeuser:mikemirzayanov title:testlib— search containing "testlib" in title by MikeMirzayanov"vk cup"— use quotes to find phrase as istitle:educational— search in title
Results
1.
Codeforces Round #752 #### UPD: (28 April, 2022)
<spoiler summary="Donated Finally">
Details: [here](https://codeforces.com/blog/entry/96333?#comment-907470)
</spoiler>
আবার চলে এসেছি! (That's Bengali for "I am back! (in Terminator mode)")
I am super excited to invite you to participate in [contest:1603] and [contest:1604] which will be held on [contest_time:1604]. This round is rated for both divisions.
You will be given $6$ problems in each division and $2$ hours to solve them. All the problems are authored and prepared by me.
I would like to thank -
- [user:antontrygubO_o,2021-10-26] for his breathtaking(<strike>literally</strike>) coordination of the round. <i style="color:White;"> no funny text this time</i>
- [user:Alpha_Q,2021-10-26], [user:Anachor,2021-10-26] and [user:antontrygubO_o,2021-10-26] for putting up with my dumb ranting and helping with the problems.
- [user:Um_nik,2021-10-26], [user:gamegame,2021-10-26], [user:kefaa2,2021-10-26], [user:dorijanlendvaj,2021-10-26], [u...
Announcement of Codeforces Round 752 (Div. 1)
Announcement of Codeforces Round 752 (Div. 2)
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...
solutions of [user:SelectorUnlimited,2022-02-02], [user:WaggleCollide,2022
-02-02], and, witnessing a confrontation between [user:tourist,2022-02-02] and AI in near
future. What do you think?, You should read solutions of [user:SelectorUnlimited,2022-02-02],
[user:WaggleCollide,2022-02-02
3.
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...
The first tester tested on 10 October **2022**. , ], [user:bensonlzl,2024-01-02] for testing a subset of the problems in 2022. -
[user:MikeMirzayanov,2023
Announcement of Hello 2024
4.
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!, that 2022 is pronounced like "2020 too". Not that. I want a completely
different year! Anyway, we, to the round coordinators and writers! You make our community richer. Please
make us happy in2022!, Hello, 2022!, Oh yes, 2021 ends! I recently realized that 2022 is pronounced like "2020 too".
Not that. I want a
5.
Educational Codeforces Round 121 [рейтинговый для Div. 2] Привет, Codeforces!
В [contest_time:1626] состоится [contest:1626].
Продолжается серия образовательных раундов в рамках инициативы [Harbour.Space University](https://harbour.space/)! Подробности о сотрудничестве [Harbour.Space University](https://harbour.space/) и Codeforces можно прочитать <a href="http://codeforces.com/blog/entry/51208">в посте</a>.
Этот раунд будет **рейтинговым для участников с рейтингом менее 2100**. Соревнование будет проводиться по немного расширенным правилам ICPC. Штраф за каждую неверную посылку до посылки, являющейся полным решением, равен 10 минутам. После окончания раунда будет период времени длительностью в 12 часов, в течение которого вы можете попробовать взломать абсолютно любое решение (в том числе свое). Причем исходный код будет предоставлен не только для чтения, но и для копирования.
Вам будет предложено **6 или 7 задач на 2 часа**. Мы надеемся, что вам они покажутся интересными.
Задачи вместе со мной придумывали и готовили Адилбек [...
[user:adedalic,2022-01-15] Далабаев, Владимир [user:vovuh,2022-01-15] Петров,
Иван [user:BledDest, hours** to solve them. The problems were invented and prepared by Adilbek
[user:adedalic,2022-01, The problems were invented and prepared by Adilbek [user:adedalic,2022-01-15]
Dalabaev, Vladimir, Задачи вместе со мной придумывали и готовили Адилбек [user:adedalic,2022-01-15]
Далабаев, Владимир
Announcement of Educational Codeforces Round 121 (Rated for Div. 2)
6.
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! We ([user:Nanako,2022-12-27], [user:m_99,2022-12-27],
[user:huangxiaohua,2022, * [user:errorgorn,2022-12-27], for useful guidance and brilliant advice during
the coordination, 1. [user:Benq,2022-12-30] 2. [user:maroonrk,2022-12-30] 3. [user:Radewoosh,2022
-12-30] 4, We ([user:Nanako,2022-12-27], [user:m_99,2022-12-27], [user:huangxiaohua,2022
-12-27, We hope you enjoy our problems and say Goodbye to your 2022 happily!
7.
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]...
are evaluating the period
from the summer of 2022 to the summer of 2023 in comparison to the, version, and our data collection broke. We are evaluating the period
from the summer of 2022 to
8.
Self-deception: maybe why you're still grey after practicing every day I generally don't like to give much advice on "how to practice", but recently I have been thinking a lot about this and I realized that there is something that I believe affects a lot of people (though it is admittedly hard to tell) that barely gets talked about: self-deception.
Self-deception is a devious thing. It can be very hard to detect, yet can be fatal to improvement.
This blog is mainly directed to greys, greens and cyans that can't get out of these categories. Most examples are given with that in mind. That being said, I believe others have something to think about as well.
This is my first blog on such "psychological issues" and I don't know if I'll ever make another one. It's certainly a difficult topic to write about because for most of the blog, the message is "your practice is not as good as you think it is" or even "you aren't as good as you think you are" which can of course be a hard thing to hear. Thus, I have to somehow be very gentle while getting the poin...
. I want to thank [user:poomas,2022-01-02], [user:nor,2022-01-02],
[user:SlavicG,2022-01-02] and, I want to thank [user:poomas,2022-01-02], [user:nor,2022-01-02], [user:SlavicG,
2022-01-02] and
9.
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...
** to solve them. All problems were written and prepared by [user:Cirno_9baka,
2022-07-23, - [user:3.141592653,2022-07-25], [user:emorgan5289,2022-07-25], [user:errorgorn,
2022-07-25, - [user:74TrAkToR,2022-07-25] for his excellent round coordination and help
with preparation, - [user:MikeMirzayanov,2022-07-08] for great systems Codeforces and Polygon, - [user:MinakoKojima,2022-07-26], [user:Ynoi,2022-07-26], [user:Suiseiseki,2022
-07-26] for, - [user:magnus.hegdahl,2022-07-26] for strengthening the data of one problem
(but because the, 1. [user:tourist,2022-08-01] 2. [user:jiangly,2022-08-01] 3.
[user:ksun48,2022-08-01] 4, All problems were written and prepared by [user:Cirno_9baka,2022-07-23],
[user:CoupDeGrace,2022-07
Announcement of CodeTON Round 2 (Div. 1 + Div. 2, Rated, Prizes!)
10.
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...
July 2022, [we have been supporting](https://codeforces.com/blog/entry/104544)
Codeforces as a title, _Since July 2022, [we have been
supporting](https://codeforces.com/blog/entry/104544) Codeforces as
Announcement of CodeTON Round 5 (Div. 1 + Div. 2, Rated, Prizes!)
11.
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!
12.
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, ; margin:0 1em 1em 1em;"/> Hello, Codeforces! The year 2022 is finally coming
to an end. Let's be, 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.
13.
VK Cup '22/23 — Отбор (Engine) и Codeforces Round #844 (Div. 1 + Div. 2) Привет!
[contest:1781] начнётся уже скоро: [contest_time:1781]. Это соревнование предназначено для тех, кто решил хотя бы 6 задач из 8 в квалификационном раунде [VK Cup 2022](https://codeforces.com/vkcup2022). Раунд будет рейтинговым.
Остальных приглашаем на открытый для всех [contest:1782], который начнётся в то же время и тоже будет рейтинговым.
Все задачи придуманы и подготовлены мной. Также этот раунд стал лучше благодаря [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].
Участникам будет предложено 8 задач и 3 часа на их решение.
64 лучших участника закрытого отборочного раунда получат фирменные футболки VK Cup, а 16 лучших пройдут в финал и смогут побороться за призы 4-5 февраля очно в офисе VK или онлайн:
- 1-е место — 300 000 рублей;
- 2-е место — 250 000 рублей;
- 3-е место — 150 000 рублей;
- 4-е место — 100 000 рублей.
...
combined rated round for both divisions and open to everyone. This round is a
mirror of VK Cup2022, для тех, кто решил хотя бы 6 задач из 8 в квалификационном раунде [VK Cup 2022
](https, решил хотя бы 6 задач из 8 в квалификационном раунде [VK Cup 2022
](https://codeforces.com/vkcup2022, This round is a mirror of VK Cup 2022 Elimination — annual programming
championship for Russian
Announcement of VK Cup 2022 - Отборочный раунд (Engine)
14.
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...
a 2022 series of [Codeforces Global
Rounds](https://codeforces.com/blog/entry/65002) supported by, раунд 2022 года из серии [Codeforces Global
Rounds](https://codeforces.com/blog/entry/65002, - [user:DmitryGrigorev,2022-02-09] for the great coordinating and helping us
with preparing, - [user:DmitryGrigorev,2022-02-09] за великолепную координацию раунда и помощь
при подготовке задач, 1. [user:tourist,2022-02-12] 1. [user:Um_nik,2022-02-12] 1.
[user:Maksim1744,2022-02-12] 1, It is the first round of a 2022 series of [Codeforces Global
Rounds](https://codeforces.com/blog, The presents for the 6-round series in 2022:, The problems were written and prepared by [user:Mangooste,2022-02-09],
[user:TeaTime,2022-02-09, Задачи раунда были придуманы и подготовлены [user:Mangooste,2022-02-09],
[user:TeaTime,2022-02-09, Призы в серии из 6 раундов в 2022 году:, Это первый раунд 2022 года из серии [Codeforces Global
Rounds](https://codeforces.com/blog/entry
Announcement of Codeforces Global Round 19
15.
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...
I'm happy to announce that starting July 2022, we have the option to increase
problem writer, The TON Foundation has already supported the CodeTON Round 1 earlier in March
2022. More than 22K
16.
Codeforces Global Round 20 On [contest_time:1672], we will host [contest:1672].
**Note the unusual timing, it is 30 minutes earlier.** <strong><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%;"></strong>
This is the second round of the 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.
T...
%;"> This is the second round of the 2022 series of [Codeforces Global
Rounds](https, - [user:antonTrygubO_o,2022-04-20] for coordinating our round and somehow only
rejecting 2 div2As, All problems were written and prepared by [user:errorgorn,2022-04-20],
[user:maomao90,2022-04-20, Also, please upvote the blog so that I can get more contribution than
[user:antonTrygubO_o,2022-04, PS: We would like to take this opportunity to congratulate [user:rotavirus,2022
-04-20] or, Thanks to XTX, which in 2022 supported the global rounds initiaitive!, The prizes for the 6-round series in 2022:, This is the second round of the 2022 series of [Codeforces Global
Rounds](https://codeforces.com
Announcement of Codeforces Global Round 20
17.
Copied problem in Codeforces Round #819 (Div. 1 + Div. 2) and Grimoire of Code Annual Contest 2022 While solving random problems on DMOJ I found this problem: [Problem](https://dmoj.ca/problem/tle16c8p6), [Contest the problem appeared in](https://dmoj.ca/contest/tle16c8). I only read the statement and decided it was not for me, so I moved on. Today after the round I remembered this problem because it seemed similar to [problem:1726F]. Not only are the problems exactly the same, they even share the same sample and the explanation of the sample is also the same:
Together with the fact that [user:little_angel,2022-09-06] has solved this problem on DMOJ:
I am convinced that the authors of [contest:1726] have purposefully copied the problem and didn't even try to hide it. I don't think the contest should be unrated, because the impact was not that big. But ...
Copied problem in Codeforces Round #819 (Div. 1 + Div. 2) and Grimoire of Code
Annual Contest2022, /4794d5ba35c2ac6a04c57f5e5dd4e6a26477d93d.png) Together with the fact that
[user:little_angel,2022-09-06] has solved this, Together with the fact that [user:little_angel,2022-09-06] has solved this
problem on DMOJ:
18.
Codeforces Round #770 (Div. 2) Приветствуем всех людей и роботов на этом сайте!
[user:sevlll,2022-01-23], [user:crazyilian,2022-02-03], [user:Mangooste,2022-02-03], [user:imachug,2022-02-03] и <a class="rated-user user-orange" href="/profile/Alexdat2000" title="Международный мастер Alexdat2000">я</a> приглашаем всех принять участие в [Codeforces Round #770 (Div. 2)](https://codeforces.com/contests/1634), который состоится в это [contest_time:1634]. **Этот раунд будет рейтинговым для всех участников с рейтингом строго меньше 2100.** У вас будет **2 часа 30 минут** на то, чтобы решить 6 задач. В раунде будет интерактивная задача, поэтому рекомендуем новичкам ознакомиться с [руководством по интерактивным задачам](https://codeforces.com/blog/entry/45307).
Традиционный список благодарностей:
- Спасибо [user:antontrygubO_o,2022-02-03] за то, что <s>терпел</s> координировал нас в течение очень долгого времени и помог улучшить одну из задач
- Спасибо [user:alexxela12345,2022-02-03] за задачи, которые не дожили до ...
- Thanks to [user:antontrygubO_o,2022-02-03] for coordinating us for a very
long time and helping, - Спасибо [user:antontrygubO_o,2022-02-03] за то, что терпел координировал нас
в течение, Greetings to all humans and robots on this site! [user:sevlll,2022-01-23],
[user:crazyilian,2022, [user:sevlll,2022-01-23], [user:crazyilian,2022-02-03], [user:Mangooste,2022
-02-03], [user:imachug, Приветствуем всех людей и роботов на этом сайте! [user:sevlll,2022-01-23],
[user:crazyilian,2022
Announcement of Codeforces Round 770 (Div. 2)
19.
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, - [user:74traktor,2022-01-18] for great coordination of the round and
translating the statements, [user:magnus.hegdahl,2022-01-18] and I are glad to invite you to [contest:1628]
and [contest:1629
Announcement of Codeforces Round 767 (Div. 1)
Announcement of Codeforces Round 767 (Div. 2)
20.
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
21.
Codeforces Round #812 (Div.2) Hi Codeforces!
==================
[user:_dlbm17,2022-06-25], [user:Demen100ns,2022-06-25], [user:Spyofgame,2022-06-25] and I are delighted to invite you to participate in [Codeforces Round #812 (Div. 2)](https://codeforces.com/contests/1713).
- Start time: [contest_time:1713]
- Duration: **120 minutes**.
- Number of tasks: **6**, including at least **one interactive** problem. Make sure to read [this blog](https://codeforces.com/blog/entry/45307) and familiarize yourself with these types of problem before the round!
<spoiler summary="This contest is brought to you by:">
- <a href = "https://www.facebook.com/HocvienPTIT">PTIT</a>, my university.
- <a href = "https://discord.gg/vKjE9xan">Code Mely</a>, a Vietnamese fanpage for Computer Science.
</spoiler>
<img align="right" src="https://i.ibb.co/VLCYnxH/received-1102672770650793-1.png" width="60%" height="60%">
Special thanks to:
- <span>[user:errorgorn,2022-08-02] for wonderful coordination</span><span style="col...
- [user:errorgorn,2022-08-02] for wonderful coordination by, 2. [user:A_G,2022-08-07], 2. [user:Xylenox,2022-08-07], 3. [user:5cd,2022-08-07], 3. [user:kotatsugame,2022-08-07], 4. [user:jiangly,2022-08-07], 5. [user:Imot,2022-08-07], 5. [user:Rubikun,2022-08-07], Hi Codeforces! ================== [user:_dlbm17,2022-06-25], [user:Demen100ns,
2022-06-25, [user:_dlbm17,2022-06-25], [user:Demen100ns,2022-06-25], [user:Spyofgame,2022
-06-25] and I are
Announcement of Codeforces Round 812 (Div. 2)
22.
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 ...
1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;">** It is the third
round of a2022, - [user:irkstepanov,2022-06-23] for coordination, and [user:Kan,2022-06-23] for
helping as well, 1. [user:ksun48,2022-06-26] 2. [user:jiangly,2022-06-26] 3. [user:Um_nik,2022
-06-26] 4, It is the third round of a 2022 series of [Codeforces Global
Rounds](https://codeforces.com/blog, Thanks to XTX, which in 2022 supported the global rounds initiative!, The prizes for the 6-round series in 2022:
Announcement of Codeforces Global Round 21
23.
Codeforces Round #777 (Div. 2) Привки, Кодефорсес (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧
------------------
<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] и я рады пригласить вас поучаствовать в [contest:1647] _(шутка про казино)_, все задачи которого будут про маленькую девочку Мадоку. Он состоится в [contest_time:1647]. Раунд будет **рейтинговым** для всех участников с рейтингом строго меньшим **2100**. И у вас будет **2 часа**, чтобы решить **6 задач**.
Также хочется выразить благодарность следующим лицам:
- Нашему милому координатору [user:Artyom123,2022-03-10].
- Милым тестерам за милый фидбек по милым задачам: [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,2022-03-09], [user:Kon567889,2022-03-09], [user:Rened...
1.0em 1.0em 1.0em;max-width: 100.0%;max-height: 100.0%;"> [user:Igorbunov,2022
-03-10] and **I** are, tasks: [user:FelixDzerzhinsky,2020-09-14], [user:lesssia,2022-03-09],
[user:eyakm1,2022-03-09, милым задачам: [user:FelixDzerzhinsky,2020-09-14], [user:lesssia,2022-03-09],
[user:eyakm1,2022-03-09, %;max-height: 100.0%;"> [user:Igorbunov,2022-03-10] и я рады пригласить вас
поучаствовать в, **Div 1+2**
1 [user:MiracleFaFa,2022-03-11] 9457, **Div 2**
1 [user:shnirelman,2022-03-11] 6955 , [user:Igorbunov,2022-03-10] and **I** are happy to invite you to participate in
[contest:1647, [user:Igorbunov,2022-03-10] и я рады пригласить вас поучаствовать в
[contest:1647] _(шутка про
Announcement of Codeforces Round 777 (Div. 2)
24.
SWERC 2021-2022 <img src="/predownloaded/4a/fc/4afcde700751b1ef849737c2edd64e52901e8df3.png" style="width:250px; float:right; margin: 0 1em 1em 1em"/>
The Southwestern Europe Regional Contest will take place on the 23rd of April.
It is the ICPC regional contest (i.e., the winning teams will advance to the ICPC World Finals) for teams from France, Israel, Italy, Portugal, Spain, and Switzerland.
The mirror contest [contest:1662] will be held on Codeforces at [contest_time:1662] and will last 5 hours.
The mirror contest will contain all the problems from the official competition plus some additional problems.
I am the chief judge for the competition and I want to thank:
- The amazing set of judges who proposed and prepared the problems: [user:cescmentation_folch,2022-04-04], [user:cip999,2022-04-04], [user:Delfad0r,2022-04-04], [user:gangsterveggies,2022-04-04], [user:giove,2022-04-04], [user:gog.gerard,2022-04-04], [user:majk,2022-04-04],
[user:Petr,2022-04-04], [user:Simon,2022-04-04...
SWERC 2021-2022, Here is a comment by none other than [user:antontrygubO_o,2022, judges who proposed and prepared the problems: [user:cescmentation_folch,2022
-04-04, - The amazing set of judges who proposed and prepared the problems:
[user:cescmentation_folch,2022, 1. [user:tourist,2022-04-25], [user:ksun48,2022-04-25] 2. [user:jiangly,2022
-04-25] 3
25.
Codeforces Round #796 Hi Codeforces! Happy Dragon Boat Festival!
We are glad to invite you to our first Codeforces Round [contest:1687] and [contest:1688] which will be held on [contest_time:1687]. This round will be rated for participants of both divisions. Participants in each division will be offered 6 problems and 2 hours to solve them. The two divisions will share 3 problems.
In this round, as the best friend of the characters in Touhou Project, you are going to help them solve the problems they meet.
The problems are prepared by [user:xiaoziyao,2022-05-30], [user:Yakumo_Ran,2022-05-30], [user:SSerxhs,2022-05-30], [user:Cocoly1990,2022-05-30], [user:LilyWhite,2022-05-30], [user:Elegia,2022-05-30] and me. We hope you will enjoy this round.
Great thanks to:
- [user:74TrAkToR,2022-05-30] for good coordination of this round and translating all statements to Russian,
- [user:Yakumo_Ran,2022-05-30] for providing most tasks,
- [user:SSerxhs,2022-05-30] for preparing most tasks,
- [user:L...
- [user:74TrAkToR,2022-05-30] for good coordination of this round and
translating all statements to, . The problems are prepared by [user:xiaoziyao,2022-05-30], [user:Yakumo_Ran,
2022-05-30, 1. [user:Hanasaki,2022-06-02] 2. [user:tkended,2022-06-02] 3.
[user:avgstuBoboge,2022-06-02] 4, 1. [user:Teating_,2022-06-02] 2. [user:AgafonovArtem,2022-06-02] 3.
[user:luogubot,2022-06-02] 4, 1. [user:Um_nik,2022-06-02] 2. [user:slime,2022-06-02] 3. [user:jiangly,2022
-06-02] 4, The problems are prepared by [user:xiaoziyao,2022-05-30], [user:Yakumo_Ran,2022
-05-30
Announcement of Codeforces Round 796 (Div. 1)
Announcement of Codeforces Round 796 (Div. 2)
26.
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 ...
The first contest will be the 2022-2023 ICPC Shenyang Regional on January 28th.
The second contest
27.
How to use Codeforces [GUIDE] I see a lot of newcomers struggling to use the website to it's fullest, so I decided to write a blog that has all important information about how to use Codeforces in a single place. I will update it with time, so feel free to write your suggestions/questions in case I missed something and I will be glad to add it to the post!
I would like to thank [user:_Vanilla_,2022-02-05] and [user:mesanu,2022-02-05] for helping me write the blog, and [user:Monogon,2022-02-05], [user:down,2022-02-05] and [user:AlperenT,2022-02-05] for proofreading and giving suggestions.
#### Navigating through pages
It's possible to navigate through most pages of Codeforces using the bar on the top, I will talk about what each tab does more in depth below:
#### The Help Page
The help page contains the answer to a lot of questions about Codeforces, such as rati...
I would like to thank [user:_Vanilla_,2022-02-05] and [user:mesanu,2022-02-05]
for helping me write
28.
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...
by [user:funer,2022-05-05], [user:dark_light,2022-05-05],
[user:FreshP_0325,2022-05-05, - [user:74TrAkToR,2022-05-05] for excellent coordination of this round! And
translating the, - [user:Elder_Giang,2022-05-05], [user:ddytxdy,2022-05-05], [user:volan.de.mort,
2022-05-05, - [user:Heltion,2022-05-05] for giving valuable advice and helping us to fix
some statements., - [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, 1. [user:Kakki_Haruka,2022-05-08], 1. [user:maroonrk,2022-05-08], 2. [user:WA_On_Pretest2_Forces,2022-05-08], 2. [user:tourist,2022-05-08], 3. [user:eecs,2022-05-08], 3. [user:ouql,2022-05-08], 4. [user:KroosTheKeenGlint,2022-05-08], 4. [user:ainta,2022-05-08], 5. [user:duality,2022-05-08], The problems were written and prepared by [user:funer,2022-05-05],
[user:dark_light,2022-05-05
Announcement of Codeforces Round 789 (Div. 1)
Announcement of Codeforces Round 789 (Div. 2)
29.
Huawei IOI Camp 2022 Hi. I'm organizing an online IOI-preparation camp in collaboration with Huawei.
Every day will be a 5-hour virtual contest, then my problem analysis, and sometimes a lecture.
There will be at least 4 contests and 2 lectures.
We will do some old IOI contests (2013?) from the [IOI archive](https://codeforces.com/blog/entry/104593), CEOI (2015-2016?), or maybe JOI/JOISC — to be decided this weekend.
I don't want to do recent years like 2021 because most participants already covered it.
The example lecture topics are those from Range Queries or Trees in [Usaco Guide Platinum](https://usaco.guide/plat).
The camp is free for IOI 2022 participants.
For everybody else, the video recordings will be posted on Youtube after the camp.
By participating you get the live experience (Discord, asking questions, competing with others, leaderboards).
**Dates**: 25.07-2.08 (updated)
**Time** of every analysis/lecture: [14:00 UTC / 16:00 CEST](https://www.timeanddate.com/worldclock...
Huawei IOI Camp 2022, If you're an IOI 2022 participant or team-leader, reach out, **Schedule:** 25.07 — CEOI 2016 day 1 26.07 — CEOI 2022 day 1 + lecture 27.07, ://usaco.guide/plat). The camp is free for IOI 2022 participants. For everybody
else, the video, The camp is free for IOI 2022 participants. For everybody else, the video
recordings will be
30.
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...
_Since July 2022, [we have been supporting](/blog/entry/104544) Codeforces as a
title sponsor. This
Announcement of CodeTON Round 7 (Div. 1 + Div. 2, Rated, Prizes!)
31.
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...
разработчикам задач: Васильев [user:Allvik06,2022-08-17] Алексей, Денис
[user:Kapt,2022-08-17] Мустафин, ,2022-08-17] Mustafin, Ivan [user:__silaedr__,2022-08-17] Podvorniy, Ilya
[user:ilyakrasnovv,2022-08, ,2022-08-17] Кунявский, Дмитрий [user:cdkrot,2022-08-17] Саютин, Алеся
[user:AlesyaIvanova,2021-09, - [user:Kan,2022-08-17] for the help during preparation of the contest, - [user:Kan,2022-08-17] за помощь при разработке задач, - [user:MikeMirzayanov,2022-08-17] and [user:geranazavr555,2022-08-18] for
codeforces and polygon, - [user:MikeMirzayanov,2022-08-17] и [user:geranazavr555,2022-08-18] за
отличные системы Codeforces, - [user:Monogon,2022-08-17] for the great coordination, valuable advice, and
patience, - [user:Monogon,2022-08-17] за прекрасную координацию, полезные советы и
терпение, - task authors and developers: Vasilyev [user:Allvik06,2022-08-17] Alexey,
Denis [user:Kapt,2022-08, - testers for good proposals and important feedback: [user:zer0brain,2022-08-17, - to the wonderful teachers who made this round happen: Pavel
[user:PavelKunyavskiy,2022-08-17, - авторам и разработчикам задач: Васильев [user:Allvik06,2022-08-17] Алексей,
Денис [user:Kapt,2022, - тестерам, за хорошие предложения и важный фидбэк: [user:zer0brain,2022-08-17, 1. [user:jiangly,2022-08-20] 2. [user:kotatsugame,2022-08-20] 3.
[user:hitonanode,2022-08-20] 4, 1. [user:william556,2022-08-20] 2. [user:infurnity,2022-08-20] 3.
[user:huge_waxberry,2022-08-20
Announcement of Codeforces Round 816 (Div. 2)
32.
Codeforces Round #774 (Div. 2) Hola Codeforces!
I am happy to invite you to [contest:1646], which will take place on [contest_time:1646]. **Notice the unusual time!** **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:darkkcyan,2022-02-26] for coordination and help in problem preparation.
- [user:KAN,2022-02-26] for translating the statements.
- [user:antontrygubO_o,2022-02-26], [user:errorgorn,2022-02-26], [user:mjhun,2022-02-26], [user:wxhtzdy,2022-02-26], [user:generic_placeholder_name,2022-02-26], [user:Supermagzzz,2022-02-26], [user:ta4p,2022-02-26], [user:fishy15,2022-02-26], [user:polarity-,2022-02-26], [user:MarcosK,2022-02-26], [user:TeaTime,2022-02-26], [user:Stepavly,2022-02-26], [user:SebaMarin,2022-02-26], [user:CarusoX,2022-02-26], [user:dbsic211,2022-02-26], [user:ak2006,2022-02-26], [user:De...
- [user:darkkcyan,2022-02-26] for coordination and help in problem preparation.
- [user:KAN,2022, 1. [user:Vercingetorix,2022-3-3] 2. [user:Um_nik,2022-3-3] 3.
[user:hank55663,2022-3-3] 4, 1. [user:lydia1,2022-3-3] 2. [user:mjhmjh1104,2022-3-3] 3. [user:sbzhangjianjun,
2022-3-3] 4, : - [user:darkkcyan,2022-02-26] for coordination and help in problem
preparation. - [user:KAN,2022-02-26] for
Announcement of Codeforces Round 774 (Div. 2)
33.
April Fools Day Contest 2022 With [user:Nickolas,2022-03-29] not writing a contest this year, [user:magnus.hegdahl,2022-03-29] and I have decided to take up this sacred duty :). We would like to invite everyone on Codeforces to the [contest: 1663]. Special thanks to [user:BucketPotato,2022-03-29] for volunteering to test this contest!
The 10th April Fools Day Contest will take place on [contest_time:1663]. 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'll be given several weird problems and 2 hours to solve them. 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), and it will be unrated. 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 contests of the past years: [2012](https://codeforces.com/contest/171), [2013](htt...
April Fools Day Contest 2022, | [user:MatrixCascade_qwq,2022-04-01] | 7 (330) | 2 |
[user:kk19212,2022-04-01] | 7 (339, With [user:Nickolas,2022-03-29] not writing a contest this year,
[user:magnus.hegdahl,2022-03-29
Announcement of April Fools Day Contest 2022
34.
Codeforces Round #831 (Div. 1 + Div. 2, based on COMPFEST 14 Final) <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%;">
Halo, **Codeforces**! 🥰🥰🥰🥰
COMPFEST 14 is happy to invite you to participate in [contest:1740] on [contest_time:1740]. **Note the unusual time of the round**. The round will be **rated for everyone**. You will be given **2 hours and 45 minutes** to solve **9 problems**.
The problems are written by [user:NeoZap,2022-10-26], [user:Nyse,2022-10-26], [user:Pyqe,2022-10-26], and [user:steven.novaryo,2022-10-26].
Scoring distribution: **500 — 1000 — 1500 — 1750 — 2000 — 2500 — 2750 — 3000 — 3500**
We would like to thank:
- [user:KAN,2022-10-26] for helping to host the round;
- [user:errorgorn,2022-10-26] for the based coordination and help with the problem preparation;
- [user:Zappeko,2022-10-26] for helping with the ...
problems are written by [user:NeoZap,2022-10-26], [user:Nyse,2022-10-26],
[user:Pyqe,2022-10-26], and, - [user:KAN,2022-10-26] for helping to host the round; - [user:errorgorn,2022
-10-26] for the based, 1. [user:jiangly,2022-10-28] 2. [user:heno239,2022-10-28] 3. [user:maroonrk,2022
-10-28] 4, The problems are written by [user:NeoZap,2022-10-26], [user:Nyse,2022-10-26],
[user:Pyqe,2022-10-26
Announcement of Codeforces Round 831 (Div. 1 + Div. 2)
35.
Codeforces Round #764 (Div. 3) Привет! В [contest_time:1624] начнётся [contest:1624] — очередной Codeforces раунд для третьего дивизиона. В этом раунде будет 7-8 задач, которые подобраны по сложности так, чтобы составить интересное соревнование для участников с рейтингами до 1600. Однако все желающие, чей рейтинг 1600 и выше могут зарегистрироваться на раунд вне конкурса.
Раунд пройдет по правилам образовательных раундов. Таким образом, во время раунда задачи будут тестироваться на предварительных тестах, а после раунда будет 12-ти часовая фаза **открытых взломов**. Мы постарались сделать приличные тесты — так же как и вы, мы будем расстроены, если у многих будут падать решения после окончания контеста.
Вам будет предложено **7-8 задач** и **2 часа 15 минут** на их решение. Одна из задач интерактивная. Не забудьте прочитать [инструкцию по интерактивным задачам](https://codeforces.com/blog/entry/45307).
**Штраф** за неверную попытку в этом раунде будет равняться **10 минутам**.
[Напоминаем](https://codefo...
work. Problems have been created and written by ITMO University team:
[user:MikeMirzayanov,2022, были придуманы и написаны командой Университета ИТМО: [user:MikeMirzayanov,2022
-01-06, . Problems have been created and written by ITMO University team:
[user:MikeMirzayanov,2022-01-06, We would like to thank: [user:itohdak,2022-01-06], [user:Yogi79,2022-01-06],
[user:smtcoder, Также большое спасибо: [user:itohdak,2022-01-06], [user:Yogi79,2022-01-06],
[user:smtcoder,2022
Announcement of Codeforces Round 764 (Div. 3)
36.
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...
of the problems and his truly wonderful coordination! * [user:KAN,2022-12-31],
for rechecking and, prepare one of the problems and his truly wonderful coordination! * [user:KAN,
2022-12-31], for
Announcement of Hello 2023
37.
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...
would like to thank: - [user:74TrAkToR,2022-02-18] for excellent coordination
of the round and, - [user:74TrAkToR,2022-02-18] for excellent coordination of the round and
translating the, 1. [user:MiracleFaFa,2022-02-20] 2. [user:eecs,2022-02-20] 3. [user:YanZhuoZLY,
2022-02-20] 4, 1. [user:YanZhuoZLY,2022-02-20] 2. [user:MeliodasIRA,2022-02-20] 3.
[user:rainboy,2022-02-20] 4
Announcement of Codeforces Round 772 (Div. 2)
38.
Codeforces Round #766 (Div. 2) omg hi Codeforces!
[user:ScarletS,2022-01-12], [user:flamestorm,2022-01-12], [user:fishy15,2022-01-13], [user:saarang,2022-01-12], <a class="rated-user user-orange" href="/profile/lookcook" title="Did no work and cried for name to be here">lookcook</a> and I are glad to invite you to our Codeforces round, [contest:1627], which will be held on [contest_time:1627]. **This round will be rated for participants with rating lower than 2100**.
We would like to thank:
- [user:Monogon,2022-01-12] senpai for excellent coordination of the contest.
- [user:MikeMirzayanov,2022-01-12], for creating the amazing Codeforces and Polygon platforms!
- [user:KAN,2022-01-15], for Russian translations!
- [user:dorijanlendvaj,2022-01-12], [user:errorgorn,2022-01-12], [user:PurpleCrayon,2022-01-12], [user:generic_placeholder_name,2022-01-12], [user:blue,2022-01-12], [user:polarity-,2022-01-12], [user:atharv,2022-01-12], [user:epicxtroll,2022-01-12], [user:dbsic211,2022-01-12], [user:StArChAn...
- [user:KAN,2022-01-15], for Russian translations!, - [user:MikeMirzayanov,2022-01-12], for creating the amazing Codeforces and
Polygon platforms!, - [user:Monogon,2022-01-12] senpai for excellent coordination of the contest., - [user:dorijanlendvaj,2022-01-12], [user:errorgorn,2022-01-12],
[user:PurpleCrayon,2022-01-12, 1. [user:neal,2022-01-17], 1. [user:yxh_loves_lxr,2022-01-14], 2. [user:Alan_boyfriend,2022-01-14], 3. [user:hitonanode,2022-01-17], 4. [user:raingirl,2022-01-14], [user:ScarletS,2022-01-12], [user:flamestorm,2022-01-12],
[user:fishy15,2022-01-13], [user:saarang, omg hi Codeforces! [user:ScarletS,2022-01-12], [user:flamestorm,2022-01-12],
[user:fishy15,2022
Announcement of Codeforces Round 766 (Div. 2)
39.
[Tutorial] Collection of little techniques #### Introduction
There are a number of "small" algorithms and facts that come up again and again in problems. I feel like there I have had to explain them many times, partly because there are no blogs about them. On the other hand, writing a blog about them is also weird because there is not that much to be said. To settle these things "once and for all", I decided to write my own list about about common "small tricks" that don't really warrant a full tutorial because they can be adequately explained in a paragraph or two and there often isn't really anything to add except for padding.
This blog is partly inspired by [user:adamant,2022-03-15]'s [blog](48417) from a few years ago. At first, I wanted to mimic adamant's blog structure exactly, but I found myself wanting to write longer paragraphs and using just bolded sentences as section headers got messy. Still, each section is short enough that it would not make much sense to write separate blogs about each of these things.
A...
This blog is partly inspired by [user:adamant,2022-03-15]'s [blog](48417) from
a few years ago. At
40.
Codeforces Round #813 (Div. 2) #####Привет, Codeforces!
Мы с [user:Igorfardoc,2022-08-07] рады представить вам наш [contest:1712], который пройдет в [contest_time:1712]. **Этот раунд будет рейтинговым для участников, чей рейтинг ниже, чем 2100.**
Мы хотим выразить благодарность:
- [user:DishonoredRighteous,2022-08-07] за координацию раунда.
- [user:Um_nik,2022-08-11], [user:Ormlis,2022-08-07], [user:errorgorn,2022-08-07], [user:FairyWinx,2022-08-07], [user:golikovnik,2022-08-07], [user:74TrAkToR,2022-08-07], [user:thenymphsofdelphi,2022-08-08], [user:lox123,2022-08-07], [user:Kon567889,2022-08-07], [user:AlperenT,2022-08-07], [user:Alexdat2000,2022-08-07], [user:MagentaCobra,2022-08-07], [user:welleyth,2022-08-07], [user:_dlbm17,2022-08-08], [user:satyam_343,2022-08-07], [user:thanhchauns2,2022-08-07], [user:SlavicG,2022-08-07], [user:_Vanilla_,2022-08-07], [user:jampm,2022-08-07], [user:QuangBuiCP,2022-08-08], [user:LeCaToX,2022-08-08] за тестирование раунда и полезный фидбэк.
- [user:MikeMirzayanov,2022...
#####Hi, Codeforces! [user:Igorfardoc,2022-08-07] and I are pleased to invite
you to our, #####Привет, Codeforces! Мы с [user:Igorfardoc,2022-08-07] рады представить вам
наш [contest, - [user:DishonoredRighteous,2022-08-07] for coordinating the round. -
[user:Um_nik,2022-08-11, - [user:DishonoredRighteous,2022-08-07] за координацию раунда. - [user:Um_nik,
2022-08-11, 1. [user:iztrax,2022-08-13] 2. [user:TrungNotChung,2022-08-13] 3.
[user:Akemi-Homura,2022-08-13, 1. [user:tourist,2022-08-13] 2. [user:m_99,2022-08-13] 3. [user:jiangly,2022
-08-13] 4, [user:Igorfardoc,2022-08-07] and I are pleased to invite you to our
[contest:1712], which will be, Мы с [user:Igorfardoc,2022-08-07] рады представить вам наш [contest:1712],
который пройдет в
Announcement of Codeforces Round 813 (Div. 2)
41.
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...
4. [user:He_ren,2022-03-08], [user:orzdevinwang,2023-04-22] for our red suns
testing the round.
Announcement of Codeforces Round 872 (Div. 1)
Announcement of Codeforces Round 872 (Div. 2)
42.
Codeforces Round #829 (Div.1, Div.2, based on Moscow Team Olympiad, rated) Hi everybody,
This Sunday there will be a XX Moscow Team Olympiad, high school students competition based in Moscow that is an elimination contest for All-Russian Team Olympiad. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Open 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">51...
[user:Tikhon228,2022-10-22], [user:teraqqq,2022-10-22], [user:Ormlis,2022
-10-22], [user:sevlll777,2022-10, **UPD2:** Great thanks to the testers: [user:Um_nik,2022-10-23],
[user:dorijanlendvaj,2022-10-23, **UPD2:** Большое спасибо тестерам: [user:Um_nik,2022-10-23],
[user:dorijanlendvaj,2022-10-23, 1. [user:jiangly,2022-10-23] 2. [user:Rebelz,2022-10-23] 2.
[user:heno239,2022-10-23] 4, 1. [user:jiangly,2022-10-23] 2. [user:Rebelz,2022-10-23] 3.
[user:heno239,2022-10-23] 4, 1. [user:kzyKT,2022-10-23] 2. [user:Vitinha,2022-10-23] 3. [user:qtpk,2022
-10-23] 4, Also thanks to [user:KLPP,2022-10-22] and [user:TheOneYouWant,2022-10-22] for
providing and, Problems of this competition were prepared by [user:Tikhon228,2022-10-22],
[user:teraqqq,2022-10-22, Задачи соревнования были подготовлены [user:Tikhon228,2022-10-22],
[user:teraqqq,2022-10-22, Спасибо [user:DishonoredRighteous,2022-10-22] и [user:KAN,2022-10-22] за
координацию раунда, Также спасибо [user:KLPP,2022-10-22] и [user:TheOneYouWant,2022-10-22] за
предоставление и
Announcement of Codeforces Round 829 (Div. 1)
Announcement of Codeforces Round 829 (Div. 2)
43.
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...
- Setters: Gheorghies [user:Gheal,2022-06-17] Alexandru, Cozma [user:tibinyte,
2022-06-17] Tiberiu, - Testers: [user:LucaIlie,2022-06-17], [user:borgar02,2022-06-17],
[user:freak93,2022-06-17, - Vip-Testers: [user:Um_nik,2022-06-17], [user:antontrygubO_o,2022-06-17],
[user:BlueDiamond,2022, - [user:First_Brave_Niuniu, 2022-07-03] - [user: fAKelyh, 2022-07-03] - [user:
ifzw,2022-07-03, - [user:SSRS_,2022-07-04] - [user:heno239,2022-07-04] - [user:jiangly,2022-07-04, - [user:intrusiv,2022-06-28] for not deserving to be publicly named -
[user:tibinyte,2022-06-17, /blog/entry/103966), which will start on [Monday, July 4th, 2022, 14:35
UTC](https, /entry/103966), which will start on [Monday, July 4th, 2022, 14:35
UTC](https://www.timeanddate.com
Announcement of Codeforces Round 804 (Div. 2)
44.
SNWS 2022 streams Tune in at [twitch.tv/the__tourist](https://twitch.tv/the__tourist) at around [22:30 MSK, 11 Jan 2022](https://www.timeanddate.com/worldclock/fixedtime.html?msg=touristream:+SNWS+R1&iso=20220111T2230&p1=3396) to watch me solving [SnarkNews Winter Series 2022 Round 1](https://contest.yandex.com/snws2022/contest/23957/enter) live! First I will do the round competitively without much interaction, and I'll be up for discussing the problems on stream afterwards.
SnarkNews Winter/Summer Series (SNWS/SNSS) is organized by [user:snarknews,2022-01-11] and consists of 5 rounds. Each round is a virtual 6-problem 80-minute contest open for 10 days. The series is open to all, but problem statements are in Russian only. On stream, I'll read the problem statements automatically translated to English.
To make the stream more fun and for easier understanding of what will be going on, you're welcome to do the round yourself beforehand! If you don't understand Russian, you can also compete using au...
SNWS 2022 streams, Jan 2022
](https://www.timeanddate.com/worldclock/fixedtime.html?msg=touristream:+SNWS+R2&iso, 2022
](https://www.timeanddate.com/worldclock/fixedtime.html?msg=touristream:+SNWS+R1&iso=20220111T2230, SnarkNews Winter/Summer Series (SNWS/SNSS) is organized by [user:snarknews,2022
-01-11] and consists
45.
Codeforces Round #793 (Div. 2) Hi Codeforces!
I am pleased to invite you to [Codeforces Round #793 (Div. 2)](https://codeforces.com/contest/1682 "Adhocforces Round"), which will take place on [contest_time:1682]. 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 in the round.
All problems in this round were prepared by me and [user:rivalq,2022-05-19]. We have worked on this round for a long time and hope you find every problem interesting.
I would like to thank:
- [user:antontrygubO_o,2022-05-19] for marvellous coordination of the round.
- [user:errorgorn,2022-05-19], [user:kclee2172,2022-05-19], [user:AmShZ,2022-05-19], [user:nvmdava,2022-05-19], [user:TheScrasse,2022-05-19], [user:aryanc403,2022-05-19], [user:koderkushy,2022-05-19], [user:PurpleCrayon,2022-05-19], [user:nor,2022-05-19], [user:AlperenT,2022-05-19], [user:towrist,2022-05-19], [user:...
round. All problems in this round were prepared by me and [user:rivalq,2022
-05-19]. We have, - [user:antontrygubO_o,2022-05-19] for marvellous coordination of the round. -
[user:errorgorn, 1. [user:beduardo,2022-05-22], 1. [user:jiangly,2022-05-22], superfast AK!, 2. [user:Beduardo,2022-05-22], 2. [user:Brewess,2022-05-22], 3. [user:Kizuna_AI,2022-05-22], 3. [user:SSRS_,2022-05-22], 4. [user:MY_aespa,2022-05-22], 4. [user:neal,2022-05-22], 5. [user:csyakuoi,2022-05-22], 5. [user:turmax,2022-05-22], All problems in this round were prepared by me and [user:rivalq,2022-05-19]. We
have worked on this, Special mention to [user:AwakeAnay,2022-05-22] for the only Indian to AK the
round!
Announcement of Codeforces Round 793 (Div. 2)
46.
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 ...
- [user:Kuroni,2022-03-25] for being the problemsetter team's caretaker the, - [user:MikeMirzayanov,2022-03-25] for great Codeforces and Polygon platforms., - [user:Monarchuwu,2022-03-25] for breathing and [user:SPyofgame,2022-03-25]
for being the team's, - [user:Spyofgame,2022-03-25] and myself for setting problems and
[user:_FireGhost_,2022-03-25, - [user:_FireGhost_,2022-03-25], [user:Mewnian,2022-03-25], [user:_LEOS_,2022
-03-25] and, - [user:antontrygubO_o,2022-03-25] for providing the idea for one of the
problems., - [user:antontrygubO_o,2022-03-25], [user:Kuroni,2022-03-25],
[user:thenymphsofdelphi,2022-03-25, - [user:errorgorn,2022-03-25] for rejecting 20 problems from , - [user:unreal.eugene,2022-03-26], [user:geranazavr555,2022-03-26] and
[user:MikeMirzayanov,2022-03, 1. [user:tourist,2022-04-05] 2. [user:MeliodasIRA,2022-04-05] 3.
[user:A-SOUL_Official,2022-04-05, Me, [user:_FireGhost_,2022-03-25] and [user:Spyofgame,2022-03-25] are glad to
invite you to, Xin chào, Codeforces! (Hello, Codeforces!) ٩ (◕‿◕｡) ۶ Me, [user:_FireGhost_,2022
-03-25] and
Announcement of Codeforces Round 779 (Div. 2)
47.
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...
also like to thank: - Our red sun [user:orzdevinwang,2022-11-19], the youngest
TOP10 coder in, - Our red sun [user:orzdevinwang,2022-11-19], the youngest TOP10 coder in
history, for illuminating, - [user:tourist,2022-11-21] - [user:dorijanlendvaj,2022-11-21] - [user:mnbvmar,
2022-11-21
Announcement of Pinely Round 1 (Div. 1 + Div. 2)
48.
Codeforces Round #800 Hi Codeforces!
[user:Keshi,2022-06-13], [user:alireza_kaviani,2022-06-13] and I are delighted to invite you to participate in [contest:1693] and [contest:1694].
- Start time: [contest_time:1693]
- Duration: $120$ minutes
- Number of Tasks: $6$ for both divisions
- Rated range: ($-\infty$,$1899$] for Div2, [$1900$, $\infty$) for Div1
We are honored to have set the 800th Codeforces round. We wish this wonderful platform all the best along with many other exciting rounds.
Huge thanks to the following people:
- [user:antontrygubO_o,2022-06-13] for his breath-taking coordination.
- Our testers [user:um_nik,2022-06-13], [user:errorgorn,2022-06-13], [user:koosha_mv,2022-06-13], [user:irkstepanov,2022-06-13], [user:ArchUser84,2022-06-13], [user:sohsoh,2022-06-13], [user:fatemetmhr,2022-06-13], [user:Dorost,2022-06-13], [user:nor,2022-06-13], [user:pooya-shams,2022-06-13], [user:Arnch,2022-06-13], [user:Kahou,2022-06-13] and [user:mosaev,2022-06-13] for testing the round an...
- Our testers [user:um_nik,2022-06-13], [user:errorgorn,2022-06-13],
[user:koosha_mv,2022-06-13, - [user:MikeMirzayanov,2022-06-13] for the amazing platforms Codeforces and
Polygon!, - [user:Radiohead,2022-06-15] because we got inspiration from them while coming
up with task names., - [user:antontrygubO_o,2022-06-13] for his breath-taking coordination., Hi Codeforces! [user:Keshi,2022-06-13], [user:alireza_kaviani,2022-06-13] and I
are delighted to, [user:Keshi,2022-06-13], [user:alireza_kaviani,2022-06-13] and I are delighted
to invite you to
Announcement of Codeforces Round 800 (Div. 1)
Announcement of Codeforces Round 800 (Div. 2)
49.
Codeforces Round 794 Announcement We will hold [contest:1685] and [contest:1686].
<ul>
<li> Contest URLs: <a href="https://codeforces.com/contest/1685">https://codeforces.com/contest/1685, <a href="https://codeforces.com/contest/1686">https://codeforces.com/contest/1686 </li>
<li> <b> Unusual </b> start time: [contest_time:1685] </li>
<li> Duration: 135 minutes </li>
<li> Number of Tasks: 6 for Div2, 5 for Div1 </li>
<li> Rated range: $(-\infty, 1899]$ for Div2, $[1900, \infty)$ for Div1 </li>
<li> Writer: [user:antontrygubO_o,2022-05-22] </li>
<li> Testers: [user:golions,2022-05-22], [user:oleh1421,2022-05-22], [user:Geothermal,2022-05-22], [user:nor,2022-05-22], [user:TheScrasse,2022-05-22], [user:timreizin,2022-05-22], [user:emorgan5289,2022-05-22], [user:Um_nik,2022-05-22], [user:mhq,2022-05-22], [user:Kuroni,2022-05-24], [user:ak2006,2022-05-24] </li>
<li> VIP-tester: [user:errorgorn,2022-05-22] </li>
<li> Coordinator and author of one problem without which round would be unbalanced: [user:dario...
**1.** [user:lmqzzz,2022-05-26], **1.** [user:slime,2022-05-26], **2.** [user:Teating_,2022-05-26], **2.** [user:jiangly,2022-05-26], **3.** [user:ecnerwala,2022-05-26], **3.** [user:lunchbox,2022-05-26], **4.** [user:gamegame,2022-05-26], **5.** [user:demacia,2022-05-26], **5.** [user:maroonrk,2022-05-26], , \infty)$ for Div1
* Writer: [user:antontrygubO_o,2022-05-22]
* Testers, : [user:antontrygubO_o,2022-05-22]
* Testers: [user:golions,2022-05-22], [user:oleh1421,2022-05-22
Announcement of Codeforces Round 794 (Div. 1)
Announcement of Codeforces Round 794 (Div. 2)
50.
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 ...
is the sixth round of a 2022 series of [Codeforces Global
Rounds](https://codeforces.com/blog/entry, - [user:errorgorn,2022-11-25] for 🥵 and 🥶 coordination. - [user:KAN,2022-11-25, Thanks to XTX, which in 2022 supported the global rounds initiative!, The prizes for the 6-round series in 2022:, The problems were written and prepared by [user:Cocoly1990,2022-11-25],
[user:waaitg,2022-11-25
Announcement of Codeforces Global Round 24
51.
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...
_Since July 2022, [we have been supporting](/blog/entry/104544) Codeforces as a
title sponsor. This
Announcement of CodeTON Round 4 (Div. 1 + Div. 2, Rated, Prizes!)
52.
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...
- [user:AquaMoon,2022-10-31], [user:mejiamejia,2022-10-31],
[user:ugly2333,2022-11-05, - [user:Benq,2022-11-06] - [user:zh0ukangyang,2022-11-06] - [user:WYZFL,2022
-11-06, - [user:Lemur95,2022-10-31], [user:Gheal,2022-10-31], [user:Perpetually_Purple,
2022-10-31, - [user:MikeMirzayanov,2022-10-31] for great platforms,
[**codeforces**](https://codeforces.com, - [user:errorgorn,2022-10-31] for being a VIP-tester.
Announcement of CodeTON Round 3 (Div. 1 + Div. 2, Rated, Prizes!)
53.
AtCoder World Tour Finals 2022 Announcement (with Rated Mirrors) We will hold AtCoder World Tour Finals 2022.
List of Finalists:
<table border="1">
<tr align="center"><td>AtCoder ID</td><td>Codeforces ID</td><td>Advanced Years</td></tr>
<tr align="center"><td>[tourist](https://atcoder.jp/users/tourist)</td><td>[user:tourist,2023-09-06]</td><td>2019,2020,2021,2022</td></tr>
<tr align="center"><td>[ksun48](https://atcoder.jp/users/ksun48)</td><td>[user:ksun48,2023-09-06]</td><td>2019,2021,2022</td></tr>
<tr align="center"><td>[Benq](https://atcoder.jp/users/Benq)</td><td>[user:Benq,2023-09-06]</td><td>2020,2021</td></tr>
<tr align="center"><td>[Um_nik](https://atcoder.jp/users/Um_nik)</td><td>[user:Um_nik,2023-09-06]</td><td>2019,2020</td></tr>
<tr align="center"><td>[apiad](https://atcoder.jp/users/apiad)</td><td>[user:amiya,2023-09-06]</td><td>2019,2021,2022</td></tr>
<tr align="center"><td>[Stonefeang](https://atcoder.jp/users/Stonefeang)</td><td>[user:Radewoosh,2023-09-06]</td><td>2020</td></tr>
<tr align="center"><td>[ecnerwala](https...
AtCoder World Tour Finals 2022 Announcement (with Rated Mirrors), AtCoder World Tour Finals 2022 is an international onsite contest. We have
invited top-runners of, We will hold AtCoder World Tour Finals 2022.
54.
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!), [user:rivalq,2022-12-15]., solve them. All problems were written and prepared by [user:Ecrade_,2022-12-14, 1. [user:Um_nik,2022-12-18] 2. [user:maroonrk,2022-12-18] 3. [user:tourist,2022
-12-18] 4, All problems were written and prepared by [user:Ecrade_,2022-12-14],
[user:Little09,2022-12-14, And thanks to [user:dorijanlendvaj,2022-12-14], [user:gisp_zjz,2022-12-14],
[user:gamegame,2022-12
Announcement of Polynomial Round 2022 (Div. 1 + Div. 2, Rated, Prizes!)
55.
Codeforces Round #788 (Div. 2) <spoiler summary="عيد سعيد(Happy Eid), Codeforces!">
<img src="https://i.imgur.com/frdxaAH.png" />
</spoiler>
I'm glad to invite you to [contest:1670], which will be held on [contest_time:1670].
This round is rated for the participants with rating lower than 2100.
You will be given **6 problems** and **2 hours** to solve them. All problems were prepared by me, [user:Hemose,2022-05-04] and [user:ZerooCool,2022-05-04].
I would like to thank:
- [user:Monogon,2022-05-04], for a lot of things (awesome coordination, helping in preparation, rejecting only not interesting tasks and a lot of useful discussions).
- [user:I_Love_Slim,2022-05-04] for teaching us <s>BLABIZO</s> useful concepts.
- Our army of testers [user:YahiaSherif,2022-05-04], [user:DeadlyPillow,2022-05-04], [user:TheScrasse,2022-05-04], [user:Bakry,2022-05-04], [user:IsaacMoris,2022-05-04], [user:TeaTime,2022-05-04], [user:magnus.hegdahl,2022-05-04], [user:generic_placeholder_name,2022-05-04], [user:...
**6 problems** and **2 hours** to solve them. All problems were prepared by
me, [user:Hemose,2022-05, , [user:Hemose,2022-05-04] and [user:ZerooCool,2022-05-04]., - Our army of testers [user:YahiaSherif,2022-05-04], [user:DeadlyPillow,2022
-05-04
Announcement of Codeforces Round 788 (Div. 2)
56.
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...
- [user:_gxyd,2022-12-15] - [user:NoPotato,2022-12-15] - [user:Alphaqwq_,2022
-12-15, - [user:errorgorn,2022-12-13] for amazing coordination and help with the
problem preparation, - [user:jiangly,2022-12-15] - [user:antontrygubO_o,2022-12-15] -
[user:Hyperbolic,2022-12-15, Hello, Codeforces! [user:amurto,2022-12-13] and I are glad to invite everyone
to participate in
Announcement of Codeforces Round 838 (Div. 2)
57.
Codeforces Round #809 (Div. 2) Hi Codeforces,
We're excited to invite you to [contest:1706], which will take place at [contest_time:1706]. All problems were created and prepared by [user:lunchbox,2022-07-16], [user:lce4113,2022-07-16], and me. It will be rated for all participants with ratings lower than 2100.
Thanks to the people that made this round possible:
- [user:IgorI,2022-07-16] for coordinating the round, patiently guiding us through the preparation process, and translating all statements to Russian.
- [user:KAN,2022-07-16], for guiding and assisting [user:IgorI,2022-07-16] in the coordination.
- [user:Apple_Method,2022-07-16], [user:izhang,2022-07-16], [user:lethan3,2022-07-16], [user:moo.,2022-07-16], [user:null_awe,2022-07-16], and [user:ezraft,2022-07-16] for proposing problems that didn't make it to the final version of the round.
- [user:PurpleCrayon,2022-07-16] for feedback and suggestions in the early stages of the round.
- Our testers, for their time and feedback: [user:EnDeRBeaT,2022-...
[contest_time:1706]. All problems were created and prepared by [user:lunchbox,
2022-07-16], [user:lce4113,2022, #### Everyone 1. [user:tourist,2022-07-18] 2. [user:SSRS_,2022-07-18] 3.
[user:WYZFL,2022-07-18, #### Official 1. [user:WYZFL,2022-07-18] 2. [user:c8k,2022-07-18] 3.
[user:tiger1926,2022-07-18, - [user:IgorI,2022-07-16] for coordinating the round, patiently guiding us
through the preparation
Announcement of Codeforces Round 809 (Div. 2)
58.
Polynomial Round 2022 (Div. 1 + Div. 2) Editorial Thanks for your participation! I am so sorry for my careless review. We were preparing for this round for many months and made some problems which writers and testers are all like. We do want to give everyone a good time to enjoy the contest. But carelessness is deadly. In problem B, some test cases should have been made, but we missed them in not only the pretests but also the final tests. In fact, we had not noticed it until some suspicious hacks appeared. I and all co-authors sincerely regret our mistake and hope you can forgive us.
Besides, few people are cyberbullying authors, please do not do so. If you have a bad experience, you can downvote me because of our fault.
[problem:1774A]
Idea: [user:cirno_9baka,2022-12-17]
<spoiler summary="Solution">
The answer is the number of $1$s modulo $2$.
We can get that by adding '-' before the $\text{2nd}, \text{4th}, \cdots, 2k\text{-th}$ $1$, and '+' before the $\text{3rd}, \text{5th}, \cdots, 2k+1\text{-th}$ $1$.
</spoiler...
Polynomial Round 2022 (Div. 1 + Div. 2) Editorial, [problem:1774A] Idea: [user:cirno_9baka,2022-12-17], [problem:1774B] Idea: [user:cirno_9baka,2022-12-17], [problem:1774D] Idea: [user:mejiamejia,2022-12-17] and [user:AquaMoon,2022
-12-17], [problem:1774E] Idea: [user:cirno_9baka,2022-12-17], [problem:1774G] Idea: [user:ChthollyNotaSeniorious,2022-12-17] and
[user:DataStructures,2022-12, [problem:1774H] Idea: [user:Ecrade_,2022-12-17]
59.
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...
), [2022](https://codeforces.com/contest/1663),
[2023](https://codeforces.com/contest/1812). (It has
Announcement of April Fools Day Contest 2024
60.
SEERC 2022 and Mirror Contest 
Hi everyone!
2022 Southeastern Europe Regional Contest will take place tomorrow, on December 10. The contest was prepared by [user:bicsi,2021-12-09], [user:antontrygubO_o,2022-12-09], [user:theodor.moroianu,2022-12-09], [user:lungualex00,2022-12-09], [user:eudanip,2022-12-09].
Good luck to the official participants!
There will be a mirror of this contest [this Sunday, December 11, 08:00 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=SEERC+2022+Mirror&iso=20221211T08&p1=1440&ah=5). It will be held by the link [https://seerc2022.eolymp.io/](https://seerc2022.eolymp.io/).
We hope that you will enjoy the contest! See you on the scoreboard.
**UPD1:** Congratulations to the winners of SEERC!
This year, the contest was held on two sites, Ukrainian and Romanian.
[Standings](https://eh211b8fkj.eolymp.space/s/seerc2022-ukr) and **Top 5 of Ukrainian site:*...
SEERC 2022 and Mirror Contest, | | - | - | - | - | - | - | - | | 1 | [Ukraine] LNU Stallions |
[user:Yarema.st,2022-12-10] | [user:mshcherba, .png) Hi everyone! 2022 Southeastern Europe Regional Contest will take place
tomorrow, on, 2022 Southeastern Europe Regional Contest will take place tomorrow, on December
10. The contest was, ] | [user:TadijaSebez,2022-12-10] | [user:stefanbalaz2,2022-12-10] | 11 | 1272
| | 2 | [Cyprus] bird-cherry
61.
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), ,2022-03-03], [user:unreal.eugene,2022-03-03], [user:dk318,2022-03-03] and me.
62.
Northern Eurasia Finals 2022 has concluded Two days ago Northern Eurasia Finals 2022 [took place](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Northern+Eurasia+Finals+2022&iso=20221207T1015&p1=352&ah=5), mirror of which was on Codeforces: [contest:1773]. In the next few hours the [standings](http://nerc.itmo.ru/archive/2022/standings.html) got unfrozen, thereby we know the list of the teams that qualified to the ICPC Finals this year:
**1<sup>st</sup> place 🏆** [MIPT](https://codeforces.com/ratings/organization/38): Yolki-palki ([user:Pechalka,2022-12-09], [user:Kapt,2022-12-09], [user:Tikhon228,2022-12-09])
**2<sup>nd</sup> place 🥇** [HSE](https://codeforces.com/ratings/organization/250): FFTilted ([user:Kirill22,2022-12-09], [user:teraqqq,2022-12-09], [user:Ormlis,2022-12-09])
**3<sup>rd</sup> place 🥇** [SPb SU](https://codeforces.com/ratings/organization/16): Urgant Team ([user:sava-cska,2022-12-09], [user:74TrAkToR,2022-12-09], [user:orz,2022-12-09])
**4<sup>th</sup> place &#...
Northern Eurasia Finals 2022 has concluded, ([user:Kirill22,2022-12-09], [user:teraqqq,2022-12-09], [user:Ormlis,2022
-12-09]), ([user:Xrite,2022-12-09], [user:vmos1999,2022-12-09], [user:nekpot,2022-12-09]), ([user:kartel,2022-12-09], [user:p3rfect,2022-12-09], [user:romarkovets,2022
-12-09]), Team ([user:sava-cska,2022-12-09], [user:74TrAkToR,2022-12-09], [user:orz,2022
-12-09]), together strong ([user:voyrus,2022-12-09], [user:Vladithur,2022-12-09],
[user:revelcoS,2022-12-09]), ): 1: Dungeon Thread ([user:Septimelon,2022-12-09], [user:RED_INSIDE,2022-12-09, ): DeoxyriboNucleic Acid ([user:windazz,2022-12-09], [user:Na2a,2022-12-09],
[user:DimmyT,2022-12-09]), ): U A ([user:Farhod_Farmon,2022-12-09], [user:Mprimus,2022-12-09], [user:Laggy,
2022-12-09]), ): pengzoo ([user:iakovlev.zakhar,2022-12-09], [user:DishonoredRighteous,2022
-12-09], [user:golikovnik,2022, -palki ([user:Pechalka,2022-12-09], [user:Kapt,2022-12-09],
[user:Tikhon228,2022-12-09]), ? ([user:dulatcodes,2022-12-09], [user:CMaster,2022-12-09], [user:krauch,2022
-12-09]), Two days ago Northern Eurasia Finals 2022 [took
place](https://www.timeanddate.com/worldclock
63.
On "is this greedy or DP", forcing and rubber bands #### Introduction
When it comes to "problem-solving techniques", there are roughly 3 levels:
1. Concrete algorithms (Kruskal's algorithm, Li-Chao tree, fast Fourier transform)
2. General patterns (dynamic programming, greedy, square-root decomposition)
3. Meta-strategies ("how do I even go about solving this problem?")
There is some grey area, but in general this classification works well.
[Many tutorials](https://codeforces.com/catalog) have been written about ideas that fall into 1 or 2.
But very little has been written about the third category. On the catalog, I think the
only blogs that really qualify are [this](62730) and [this](20548). There is also
[this](92248?#comment-809401) valuable comment. As to why there is so little written,
I think I can identify two reasons.
- Most strong contestants don't really consciously think about these.
After solving a problem with FFT, it's hard not to know you used FFT.
If you used DP, even if you did it without thinki...
[user:-is-this-fft-,2022-08-24].
64.
SWERC 2022-2023 <img src="/predownloaded/70/37/703737cf76db63e4b7bbb9fd63a01a3dc446371e.png" style="width:250px; float:right; margin: 0 1em 1em 1em"/>
The Southwestern Europe Regional Contest will take place on the 19th of February in Milan.
It is the ICPC regional contest (i.e., the winning teams will advance to the ICPC World Finals) for teams from France, Israel, Italy, Portugal, Spain, and Switzerland.
The mirror contest [contest:1776] will be held on Codeforces at [contest_time:1776] and will last 5 hours.
The mirror contest will contain the problems from the official competition plus some additional problems.
I am the chief judge for the competition and I want to thank:
- The amazing set of judges who proposed and prepared the problems: [user:cescmentation_folch,2023-01-24], [user:cip999,2023-01-24] (vice chief judge), [user:gangsterveggies,2023-01-24], [user:giove,2023-01-24], [user:gog.gerard,2023-01-24], [user:jinlifu1999,2023-01-24],
[user:Petr,2023-01-24], [user:Simon,2023...
SWERC 2022-2023, organization of SWERC, in particular [user:dariost,2022-04-06] \(director) and
[user:edomora97,2022
65.
8-hour Long Stream In Support Of Ukraine (With Great Guests!) **UPD: schedule, list of guests, and [questions form](https://forms.gle/tyQjuHd3bYYwt5dV9) for guests added.**
**UPD2: link to the stream: [https://youtu.be/WZKOdorb1Dg](https://youtu.be/WZKOdorb1Dg)**
I know that lots of you were saying that Codeforces should stay out of politics when there were lots of blog posts supporting Ukraine a couple of weeks ago. Well, I respect your opinion, but I can't agree. If you see a binary search tutorial on the "Top" page, do you complain about it if you're not interested in binary search, or do you just ignore it? And at the end of the day, it's not really about politics, but about people's lives.
Having said that, I'd like to invite you to join my 8-hour long live stream on YouTube against the Russian invasion of Ukraine **next Sunday (27th of March) from 10 AM till 6 PM Ukrainian time** (be careful, 27th of March is a daylight saving start in Ukraine and a lot of other countries, but it may not be the case for your country, so check your ...
10:30-11:00 — Interview with Matt [user:tehqin,2022-03-24] Fontaine (author of
[Algorithms Live, 11:30-12:00 — Interview with Nikita [user:nskybytskyi,2022-03-24] Skybytskyi
(author of [Nikita, 16:00-16:30 — Interview with Anton [user:antontrygubO_o,2022-03-25] Trygub, 16:45-17:15 — Interview with Jay [user:Geothermal,2022-03-24] Leeds (author of
[Jay Leeds, 17:15-17:45 — Interview with Ildar [user:300iq,2022-03-24] Gainullin (IOI 2019
2nd place)
66.
Codeforces Round #832 (Div. 2) Hi Codeforces!
I am pleased to invite you to <strike> Adhocforces</strike>, <strike> Mathforces</strike> [Codeforces Round #832 (Div. 2)](https://codeforces.com/contest/1747), which will take place on [Friday, Nov 4, 2022 at 14:35 UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg=Codeforces+Round+832&iso=20221104T1435&p1=%3A&ah=2). 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 in this round were prepared by me and [user:coderanshu,2022-11-02].
I would like to thank:
- [user:antontrygubO_o,2022-11-02] for coordination of the round.
- [user:ffao,2022-11-02], [user:Everule,2022-11-02], [user:Andreasyan,2022-11-02], [user:koderkushy,2022-11-02], [user:nor,2022-11-02], [user:AlperenT,2022-11-02], [user:the_hyp0cr1t3,2022-11-02], [user:Runtime-Terr0r,2022-11-02], [user:sp005,...
place on [Friday, Nov 4, 2022 at 14:35
UTC](https://www.timeanddate.com/worldclock/fixedtime.html?msg, - [user:antontrygubO_o,2022-11-02] for coordination of the round. - [user:ffao,
2022-11-02, 1. [user:OotoriEmu,2022-11-05] 2. [user:Nephren--Ruq--Insania,2022-11-05] 3.
[user:Silviasylvia, 1. [user:um_nik,2022-11-05] 2. [user:errorgorn,2022-11-05] 3. [user:turmax,2022
-11-05] 4
Announcement of Codeforces Round 832 (Div. 2)
67.
Codeforces Round #800 Editorial ###[problem:1694A]
Idea: [user:AmShZ,2022-06-16]
<spoiler summary="Solution">
[tutorial:1694A]
</spoiler>
<spoiler summary="Implementation">
~~~~~
# include <bits/stdc++.h>
using namespace std;
int t, A, B;
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> t;
while (t --){
cin >> A >> B;
for (int i = 0; i < min(A, B); ++ i)
cout << "01";
for (int i = 0; i < abs(A - B); ++ i)
cout << (A < B ? 1 : 0);
cout << '\n';
}
return 0;
}
~~~~~
</spoiler>
###[problem:1694B]
Idea: [user:AmShZ,2022-06-16]
<spoiler summary="Solution">
[tutorial:1694B]
</spoiler>
<spoiler summary="Implementation">
~~~~~
# include <bits/stdc++.h>
using namespace std;
int t, n;
string S;
long long ans;
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> t;
while (t --){
cin >> n >> S, ans = n;
for (int i = 1; i < n; ++ i)
if (S[i] != S[i - 1])
ans += i;
cout << ans << '\n';
...
Idea: [user:AmShZ,2022-06-16]
Tutorial of Codeforces Round 800 (Div. 1)
Tutorial of Codeforces Round 800 (Div. 2)
68.
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...
-2019, windows-server-2022), * different versions of different C++ compilers (g
++, clang ++, msvc
69.
Google Code Jam 2022 Finalists Google Code Jam 2022 Virtual World Finals will take place today. They have published the [list of finalists](https://developers.googleblog.com/2022/07/meet-the-2022-code-jam-world-finalists.html) recently. For some reason [user:SpyCheese,2022-08-05] and [user:duality,2022-08-05] are not in the list. And there are 26 finalists this year (not 25), here they are:
| GCJ Handle | CF Handle | Country | CF Rating | Finals before| Best place before |
|---------------|--------------|---------|-----------|-------------|--------------------------|
| [Gennady.Korotkevich](https://cphof.org/profile/gcj:Gennady.Korotkevich) | [user:tourist,2022-08-05] | Belarus | 3771 | 8 | Seven times GCJ World Champion (2014-2020) |
| [Benq](https://cphof.org/profile/gcj:Benq) | [user:Benq,2022-08-05] | United States | 3513 | 2 | 5th @ GCJ 2021 |
| [Um_nik](https://cphof.org/profile/gcj:Um_nik) | [user:Um_nik,2022-08-05] | Ukraine ...
Google Code Jam 2022 Finalists, Google Code Jam 2022 Virtual World Finals will take place today. They have
published the [list of, ](https://cphof.org/profile/gcj:Gennady.Korotkevich) | [user:tourist,2022-08-05
70.
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, - [user:darkkcyan,2022-09-17] for his excellent coordination; -
[user:anthony123,2022-09-17] and, 1. [user:GOI_Official,2022-09-23] 2. [user:822E-Liar,2022-09-23] 3.
[user:Second_Brave_Niuniu, 1. [user:GOI_Official,2022-09-23] 2. [user:Um_nik,2022-09-23] 3.
[user:822E-Liar,2022-09-23] 4
Announcement of Codeforces Round 822 (Div. 2)
71.
On Div2ABs 2 years ago, [user:antontrygubO_o,2022-04-27] wrote [a blog](https://codeforces.com/blog/entry/75163) about div2ABs where he expressed his opinions that d2ABs should not be about "here is a statement, please implement what is written there". Thanks to him, the quality of d2ABs (and problem quality in general) have certainly improved. However, I still believe that there still quite large differences between how coordinators/problemsetters view d2ABs and how the intended participants view them.
From the survey made by [user:kpw29,2022-04-27], we can see that most people agree that most people agree that we should **primarily** consider the target audience when proposing a task. I too think if a task is boring to div 1 contestants, we should not think of that as a reason to immediately disqualify a problem from being a d2A.
I think when people judge the interesting-ness of d2As, they try...
Thank you to [user:Monogon,2022-04-27], [user:Um_nik,2022-04-27],
[user:dario2994,2022-04-27
72.
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...
Many thanks to the testers: [user:SixtyWithoutExam,2022-04-19],
[user:magnus.hegdahl,2022-04-19, [user:SlavicG,2022-04-19], [user:flamestorm,2022-04-19], [user:MikeMirzayanov,
2022-04-19
Announcement of Codeforces Round 784 (Div. 4)
73.
Hosting IOI 2022 is already stressful -- I plead everyone not to make us more stressful **Disclaimer: all opinions written in this post are purely personal and not tied with any affiliation, organization, or institutional I am working with, including but not limited to the IOI 2022 organizers.** Several members within IOI 2022 organizers might even try to prevent me from posting this.
Dear IOI Community in Codeforces,
I am writing in Codeforces this time, not in e-mails or IOI 2022 website since I am writing this in personal capacity and should not reflect a formal opinion of the IOI 2022 organizers.
As you all might know, IOI 2022 will be conducted hybrid -- it will be hosted onsite, but we understand that it is impossible for some countries to come to Indonesia due to the [current global pandemic](https://en.wikipedia.org/wiki/COVID-19_pandemic), so these countries are still allowed to officially participate online.
I am going to be very honest and transparent in this post.
This is the first time the IOI has a hybrid setting like this.
This poses huge chal...
Hosting IOI 2022 is already stressful -- I plead everyone not to make us more
stressful, affiliation, organization, or institutional I am working with, including but
not limited to the IOI2022, I am writing in Codeforces this time, not in e-mails or IOI 2022 website since
I am writing this in
74.
Technocup 2022 — Elimination Round 1 and Codeforces Round #749 (Div. 1+Div. 2) Hi all!
This weekend, at [contest_time:1583] we will hold [contest:1586]. It is based on the problems of Technocup 2022 Elimination Round 1 that will be held at the same time.
**Note the unusual start time of the contest.**
Technocup is a major olympiad for Russian-speaking high-school students, so if you fall into this category, please register at <a href="https://technocup.mail.ru/">Technocup website</a> and take part in the Elimination Round.
The Div. 1 + Div.2 edition is open and rated for everyone. Register and enjoy the contests!
The problems were written and prepared by [user:Tlatoani,2021-10-16], [user:golions,2021-10-16], [user:rabaiBomkarBittalBang,2021-10-16], [user:qlf9,2021-10-16], and me.
We would like to express our thanks for [user:antontrygubO_o,2021-10-16], [user:isaf27,2021-10-16], and [user:KAN,2021-10-16] for reviewing our problems and being great coordinators!
Huge thanks to the following users for testing our round:
[user:kefaa2,2021-10-16]...
Technocup 2022 — Elimination Round 1 and Codeforces Round #749 (Div. 1+Div. 2), Technocup 2022 Elimination Round 1 that will be held at the same time.
Announcement of Technocup 2022 - Elimination Round 1
75.
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
Announcement of Good Bye 2021: 2022 is NEAR
76.
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:...
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, 1. [user:Geothermal,2022-09-19] 2. [user:SSRS_,2022-09-19] 3. [user:tabr,2022
-09-19] 4, 1. [user:dengTianliang,2022-09-19] 2. [user:i_will_be_less_than_blue,2022
-09-19] 3
Announcement of Codeforces Round 821 (Div. 2)
77.
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
78.
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...
- [user:MikeMirzayanov,2022-10-31] for great platforms,
[**codeforces**](https://codeforces.com
Announcement of Codeforces Round 875 (Div. 1)
Announcement of Codeforces Round 875 (Div. 2)
79.
Osijek Competitive Programming Camp 2023 winter Hi everyone!
<center><a href="https://ocpc.mathos.unios.hr/index.php"><img src="https://ocpc.mathos.unios.hr/images/ocpc.svg" height="100px"></a></center>
I am happy to announce the [Osijek Competitive Programming Camp](https://ocpc.mathos.unios.hr) that is scheduled to happen on **18-26 February 2023** in Osijek, Croatia. The camp is hosted by the [Department of Mathematics at J. J. Strossmayer University of Osijek](https://www.mathos.unios.hr/index.php/en/) and is brought to you by the organizing team of [user:adamant,2022-12-21] (that's me!), [user:-is-this-fft-,2023-01-06], [user:mblazev,2023-01-06], [user:Tomx,2023-01-06] and [user:antontrygubO_o,2023-01-05].
The camp is inspired by various competitive programming camps that we attended during our active years in ICPC, and is aimed to help college students prepare for ICPC regional contests and finals. The camp will consist of 7 ICPC-style contests and 2 days off.
Up until now, most top competitive programming training...
contest by prime numbers. - [user:conqueror_of_tourist,2023-01-06] — ICPC 2022
world finalist
80.
InterviewForces Contest #1 (Div. 7) Hi Codeforces!
We are pleased to invite you to [contest:383377], which will take place on [contest_time:383377]. You will be given 9 problems and 2 hours to solve them. **Please follow [this link](https://codeforces.com/contestInvitation/b5b8b43069d2d6ea2be442e374a71a84985bae68) in order to register for the contest.** Note that this contest is not an official Codeforces round.
The round will be unrated for all participants. It will be held according to modified ICPC rules.
All problems in this round were written and prepared by [user:dorijanlendvaj,2022-05-22], [user:errorgorn,2022-05-22], [user:juckter,2022-05-22], [user:nor,2022-05-22] and [user:ToxicPie9,2022-05-22]. We have worked on this round for quite a short time and hope you find every problem <s>so easy that even your five year old sibling could solve it</s> interesting.
This round is sponsored by [user:errorgorn,2022-05-22] and [user:Sexpert,2022-05-24] with the following prizes:
- 1st place: 10 lakh VEF
- 2n...
1. [user:Bench0310,2022-05-26] 2. [user:BucketPotato,2022-05-26] 3.
[user:HNO2,2022-05-26] 4
81.
Problems that I authored so far Hi everyone! I wanted to write such a blog for a long time, motivated by similar blogs [by](https://codeforces.com/blog/entry/108940) [user:adamant,2023-02-20] and [by](https://codeforces.com/blog/entry/108595) [user:tibinyte,2023-02-20]; I finally decided to do it after my Universal Cup contest. This is not a super-comprehensive list, I also set some problems for some local contests, but that's most of it.
I want to encourage other setters to write such blogs. For me, it's very interesting to read about the backstories of some problems and also to see all the problems by some author gathered in one place (as most authors give problems to several platforms).
One important point. As you will see from the comments, many of my problems were improved by other people, and I myself improved some problems by other people. I think that it's crucial to have someone to discuss your problems with (apart from the coordinator).
So, here we go.
| # | Date | Problem | Contest | Comment ...
| | | 82 | January 2022 | [Equal Number of Prefix
Maximums](https://www.codechef.com/SNCKFL21/problems, ) | SnackDown 2021 Online Elimination Round | | | 82 | January 2022 | [Equal
Number of Prefix Maximums
82.
Good Bye 2022 -- Editorial ## [problem:1770A]
Idea by [user:m_99,2022-12-30]
<spoiler summary="Hint 1">
Exactly $n$ items out of of $a_1,\ldots,a_n,b_1,\ldots,b_m$ will remain on the whiteboard at the end.
</spoiler>
<spoiler summary="Hint 2">
$b_m$ will always remain on the board at the end.
</spoiler>
<spoiler summary="Hint 3">
Consider the case where $n=2$ and $m=2$. As we mentioned in hint 2, $b_2$ will always be written, but what about $b_1$?
</spoiler>
</details>
<spoiler summary="Solution">
This problem can be solved naturally with a greedy algorithm — for $i = 1, 2, \dots, m$, we use $b_i$ to replace the minimal value among the current $a_1, a_2, \dots, a_n$. The time complexity is $O(nm)$ for each test case.
Alternatively, we can first add $b_m$ to our final sum. For the remaining $(n+m-1)$ integers, we can freely pick $(n - 1)$ out of them and add it to our final sum. This is because if we want a certain $a_i$ to remain on the board at the end, we simply do not touch i...
Good Bye 2022 -- Editorial, Idea by [user:huangxiaohua,2022-12-30] and [user:errorgorn,2022-12-30]
83.
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...
- [user:Arpa,2022-04-12] and [user:KAN,2022-04-12] for coordinating the round!
- [user:KAN,2022-04
Announcement of Codeforces Round 782 (Div. 2)
84.
BOI 2022 
This weekend, the **Baltic Olympiad in Informatics 2022** (BOI 2022) is going to take place! BOI is a programming contest for secondary school students from countries around or close to the Baltic sea. This year, around 70 contestants from Denmark, Estonia, Finland, Germany, Iceland, Latvia, Lithuania, Norway, Poland, Sweden and our guest countries Israel and Ukraine will compete against each other, solving difficult problems of algorithmic nature. Each participating country sends 6 contestants from their national olympiads which take place in the months beforehand.
The contest consists of two days, Saturday and Sunday, on each of which the contestants have 5 hours to solve 3 problems of varying difficulty. Each problem is worth 100 points that are distributed into multiple subtasks with different constraints that allow the participants to earn partial scores. During the contest, each participant receives the...
BOI 2022
Codeforces (c) Copyright 2010-2024 Mike Mirzayanov
The only programming contests Web 2.0 platform
Server time: Apr/25/2024 11:42:20 (j1).
Desktop version, switch to mobile version.
Supported by
