Привет!

В 08.12.2024 17:35 (Московское время) состоится Codeforces Round 992 (Div. 2).

Задачи написал и подготовил Igor_Parfenov.

Я хотел бы поблагодарить всех, кто сделал этот раунд возможным:

• 4mda4mda, zap4eg, triple__a, Non-origination, _Israel_, ApraCadabra, FzArK, Dominater069, ezraft, thenymphsofdelphi, Pervushev, Arthas, Khomutov за тестирование раунда и обратную связь по задачам
• Vladithur, за координацию раунда
• MikeMirzayanov, за системы Codeforces и Polygon
• Всех участников

Этот раунд будет рейтинговым для участников с рейтингом менее 2100.

У вас будет 2 часа для решения 6 задач.

Разбалловка: 500 — 1000 — 1500 — 2000 — 2250 — 2750.

Удачи!

UPD: Разбор

UPD: Поздравления победителям!

Div.2:

1. daniel6202

2. younesg

3. houseof

4. HUST_USELESS

5. FatihCihan

Div.1 + Div.2:

1. jiangly

2. maspy

3. Rubikun

4. BurnedChicken

5. neal

Привет! В 05.12.2024 17:35 (Московское время) начнётся Codeforces Round 991 (Div. 3) — очередной Codeforces раунд для третьего дивизиона. В этом раунде будет 6-8 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, после её завершения все успешные попытки будут перетестированы на успешных взломах. 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 6-8 задач и 2 часа 15 минут на их решение.

Штраф за неверную попытку в этом раунде будет равняться 10 минутам.

Напоминаем, что в таблицу официальных результатов попадут только достоверные участники третьего дивизиона. Как написано по ссылке — это вынужденная мера для борьбы с неспортивным поведением. Для квалификации в качестве достоверного участника третьего дивизиона надо:

• принять участие не менее чем в пяти рейтинговых раундах (и решить в каждом из них хотя бы одну задачу)
• не иметь в рейтинге точку 1900 или выше.

Независимо от того являетесь вы достоверными участниками третьего дивизиона или нет, если ваш рейтинг менее 1600, то раунд для вас будет рейтинговым.

Задачи были придуманы и подготовлены частью команды Интернет-олимпиад по информатике:
AVdovin, DanGolov, kbats183, Vladosiya и pskobx.

Также большое спасибо:

1. MikeMirzayanov за системы Polygon и Codeforces.

2. Vladosiya за координацию раунда.

3. EgorUlin, qsmcgogo, molney, misorin, vladmart, Blinov_Artemii за жёлтое тестирование раунда.

4. snasibov05, FBI за фиолетовое тестирование раунда.

5. artcosec, Pslnd, _icy_, Gabbasov, UniversalAdmin за синее тестирование раунда.

6. dmit_brit, WahidmShafin, Osama.Rafat100 за бирюзовое тестирование раунда.

7. Kaushal_26 за зелёное тестирование раунда.

Всем удачи!

UPD: Разбор опубликован.

Hi Codeforces!

On Dec/03/2024 09:25 (Moscow time) we will hold Codeforces Round 990 (Div. 1) and Codeforces Round 990 (Div. 2). Note the unusual starting time!

The harder problems of this round are based on the problems from the Final round of Yandex Cup 2024, Algorithms track, that will be held at the same time.

The problems are authored by elshiko, Flyce, MrLolthe1st, sokolow, stepanov.aa, TeaTime, Tikhon228, webmonster, 4qqqq with guest problems from myst-6, Vladithur, BledDest and me.

I'd like to thank daubi, Golovanov399, arbuzick, pperm, orz, AgafonovArtem, Qwerty1232, k1r1t0, Itsmylove1, Sofi_, and errorgorn for testing the problems, tourist for helping with the round, and MikeMirzayanov for the Polygon and Codeforces systems.

Because of official Yandex Cup Finals ends later than the round on Codeforces, the upsolving, solutions, and test cases will be closed until the end of the onsite contest, roughly 3 hours after the end of the Codeforces round. It is also forbidden to discuss the problems publicly until the end of the onsite round. Any comments here concerning the problems will be removed.

Good luck!

UPD: The contest has been delayed to make sure the online contest does not start earlier than the onsite one.

Congratulations to the winners!

Div. 1:

1. jiangly
2. hank55663
3. noimi
4. cxm1024
5. Pyqe

Div. 2:

1. RGB_ICPC8
2. timer2024
3. tietieAM
4. ylzxxx7
5. mion_sonozaki

UPD: You are free to discuss the problems now.

UPD: Editorial.

Привет, Codeforces!

Благодаря поддержке Neapolis University Pafos, продолжается серия образовательных раундов. Университет предлагает получение степени бакалавра в области компьютерных наук и искусственного интеллекта со стипендиями JetBrains. Получите передовые навыки в области искусственного интеллекта и машинного обучения, которые подготовят вас к востребованным техническим карьерам. Любопытно? Ознакомьтесь с учебной программой прямо сейчас. Доступно ограниченное количество стипендий. Не упустите свой шанс учиться в Европе бесплатно!

В 02.12.2024 17:35 (Московское время) состоится Educational Codeforces Round 172 (Rated for Div. 2).

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 adedalic Далабаев, Иван BledDest Андросов и Максим Neon Мещеряков. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.

Удачи в раунде! Успешных решений!

UPD: Разбор опубликован

Selamat pagi Codeforces!

We're going to hold The 2024 ICPC Asia Jakarta Regional Contest.

We invite you to join the online mirror contest 2024-2025 ICPC, Asia Jakarta Regional Contest (Online Mirror, Unrated, ICPC Rules, Teams Preferred) on Codeforces. It'll be held on Dec/01/2024 08:05 (Moscow time) and will last for 5 hours.

The mirror will be held using ICPC-style scoring with 10 to 13 problems. The problem statements will only be available in English. We encourage participating as a team using only one computer for coding (as in ICPC contests). The mirror will be unrated.

Some useful links:

• The 2024 ICPC Asia Jakarta homepage
• The regional information in ICPC Global
• The onsite scoreboard

We hope that you'll enjoy the contest. Good luck and have fun!

UPD. The mirror has ended! You can find the editorial here. The onsite scoreboard will be unfrozen after the closing ceremony. Thank you for participating and we hope that you enjoyed the problemset!

UPD2. Mistake in Problem D. Aquatic Dragon

The act of activating a shrine is supposed to be mandatory once you reach an island instead of being optional. During contest preparation, the initial problem had a statement that implies the aforementioned obligation of shrine activation, which the judges had a correct solution for (the one in the editorial). However, when rewriting the problem statement for more clarity with adjustments to the story, we ended up making it such that it's optional, without too much thought about it, thinking it's essentially still the same problem. Unfortunately, as we have recently found out after the contest, it's in fact not the same problem.

The action we're taking now is fixing the statement of the problem after the contest with the correct intended version without changing the judges' solution. We are very sorry for the inconvenience.

👋 Salam, Codeforces!

We are thrilled to invite you to the Rayan Programming Contest 2024 - Selection (Codeforces Round 989, Div. 1 + Div. 2).

The Selection Round is a rated contest for Div. 1 + Div. 2, taking place on Nov/30/2024 17:35 (Moscow time). The problems for this round were crafted and prepared by ArshiaDadras, MohammadParsaElahimanesh, AmShZ, AmirrzwM, and Keshi.

The top 60 trusted participants (with a maximum of three from each country) will qualify for the onsite Final Round in Tehran, in Spring 2025. An additional quota is reserved for the host country. Hotel accommodation, local transportation, and meals will be provided to all finalists. More details about the final contest will be available on the Rayan website.

🏆 Selection Round Prizes:

• The top 50 participants will receive T-shirts. 👕
• Additionally, 50 random participants from ranks 51-1000 will also receive T-shirts.

🏅 Final Round Prizes:

• 1st place: $15,000 💵
• 2nd place: $10,000 💵
• 3rd place: $5,000 💵
• 4th–6th places: $2,000 each
• 7th–10th places: $1,000 each

🙏 Special Thanks:

We would like to extend our deepest gratitude to:

• MikeMirzayanov for enabling this event through the amazing Codeforces platform.
• The one and only KAN for his invaluable support in hosting the round.
• Dear TheScrasse for his dedicated coordination efforts and lots of discussions about the problems and rejecting a big chunk of our problems for Problem C. He also contributed some problems to the contest, one of which was selected by the team!
• Our testers who tested and provided invaluable feedback to improve the problems: peti1234 for being our LGM (VIP) tester, wyrqwq for his great ideas and ignoring his school midterms to test the problems, Error_Yuan for helping us and picking on tough problems for no reason, Hyperbolic, DylanSmith, valeriu, Clan328, powervic08, CepryH9, mispertion20, PineapplesOnPizza, vyshniak.n, ErrorAssassin, nicolasalba, naniim, estoy-re-sebado, mika_uwu, rulerofcakes, AkiLotus, Random_3652, sleepwalking643, Leonardo_Paes, RockSnow, waidenf, and newb_programmer.
• Prof. Hamid Zarrabi Zadeh and Prof. Mohammad Ali Abam, whose leadership and organizational efforts make this event a reality. Thanks to their vision, Rayan is becoming one of the largest competitive programming contests in terms of prizes (and soon participants!).
• You for participating and getting positive delta (and maybe the final prize in the next year 💸😉).

📊 Score distribution: $$$500 - 750 - 1500 - 1500 - 2000 - (2000 + 2000) - (3000 + 3000) - 5000$$$

We look forward to seeing you both online and onsite!

Good Luck & Have Fun! 🎉

Note: Editorial just published here! 🚀🍿

Hello Codeforces!

I am pleased to invite you to participate in 2024 ICPC Asia Taichung Regional Contest (Unrated, Online Mirror, ICPC Rules, Preferably Teams), which will be held on Nov/24/2024 10:05 (Moscow time). This is an online mirror contest for the 2024 ICPC Asia Taichung Regional Contest, and the official offline contest was conducted on November 17th, 2024. The duration of the contest will be 5 hours and the contest is best for teams of three people. The mirror will use the ICPC format.

The contest tasks are proposed by the task authors (baluteshih, waynetuinfor, skylinebaby,samsam2310, hank55663, ltf0501, Jeffrey, Shik, tmt514, Bangye Wu, kasuistry, and Peter Rossmanith), prepared and polished by the judge team (Regional Contest Director Ling-Ju Hung, Chief Judge Peter Rossmanith, kasuistry, Hung-Lung Wang, baluteshih, waynetuinfor, hank55663, cthbst, Sylveon, CindyLinz, marmot0814, tmt514), and tested by the tester team (olmrgcsi, oToToT, jeeeerrrpop, nikilrselvam, Vince729, applepi216). The judges appreciate the testers for their valuable feedback!

We would like to thank MikeMirzayanov for creating the greatest Codeforces platform, and many, many, many helps for making this online mirror contest possible!

This is a photo of the contest venue. Photo Credit: Prof. Jinn-Shyong Yang.

On behalf of the 2024 ICPC Asia Taichung Regional Contest Judge Team, we hope you enjoy this contest and have fun!

Of course, this contest will be unrated.

Updated: the editorial has been released! Please refer to the link in the contest's local website.

কি অবস্থা ব্রো? আবারও চলে এসেছি! (That's Bengali for "What's up bro? I am back again!")

I am super excited to invite you to participate in CodeTON Round 9 (Div. 1 + Div. 2, Rated, Prizes!) which will be held on Nov/23/2024 17:35 (Moscow time). This round is rated for both divisions.

The contest will feature $$$8$$$ problems, with three of them divided into two subtasks each. You will have $$$3$$$ hours to solve as many as you can. The problems are authored and prepared by me and wuhudsm.

I would like to thank -

• TheScrasse and Kaey for their jaw-dropping (literally) coordination of the round, giving valuable feedback and improving lots of problems.
• wuhudsm for being kind enough to use one of his cool problems in the round.
• Alpha_Q and Raiden for discussing tons of problems with me and improving some problems.
• antontrygubO_o for sacrificing his TON by not participating in the round as he knows some of the problems as my past coordinator.
• dorijanlendvaj, wyrqwq, Alpha_Q and nfssdq for being our MVP testers and improving the round immensely.
• Thienu, wuhudsm, jdurie, Farhan132, Soumya1, redpanda, LMeyling, upobir, AlephZero01, NemanjaSo2005, tb_ro, Kawchar85, waidenf, serotonin, dazlersan1, I_Love_you_Tithi, Random_3652, Raiden and LipArcanjo for testing and improving the round as well.
• redpanda for creating awesome Manim video editorials for some of the problems.
• The great MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• You, for existing and participating in the round. Also, thanks for giving your best and not quitting. You will get what you want prettyyy soon. Just hold right there .

Score distribution:
$$$500 - 1000 - (1000 + 1500) - 2000 - 2750 - (2000 + 2000) - 4250 - (2250 + 2500)$$$

Wishing you TONs of luck — hope you have a TON of fun cracking the problems!

UPD: Editorial

UPD: Congratulations to the winners!

1. orzdevinwang
2. tourist
3. Rewinding
4. Kevin114514
5. maspy
6. Radewoosh
7. ksun48
8. jiangly
9. cn449
10. maroonrk

And here is the information from our title sponsor:

Hello, Codeforces!

We, the TON Foundation team, are pleased to support CodeTON Round 9.

The Open Network (TON) is a fully decentralized layer-1 blockchain designed to onboard billions of users to Web3.

Since July 2022, we have been supporting Codeforces as a title sponsor. This round is another way for us to contribute to the development of the community.

The winners of CodeTON Round 9 will receive valuable prizes.

The first 255 participants will receive prizes in USDT cryptocurrency in the TON network:

• 1st place: 2,560 USDT
• 2–3 places: 1,280 USDT each
• 4–7 places: 640 USDT each
• 8–15 places: 320 USDT each
• …
• 128–255 places: 20 USDT each

All participants will receive Soulbound Tokens (SBT) that reflect their developer rating

We wish you good luck at CodeTON Round 9 and hope you enjoy the contest!

Всем привет!

Третья и последняя командная интернет-олимпиада в этом сезоне состоится завтра, 23 ноября 2024 года в 15:00 (по Московскому времени). Приглашаем вас принять в ней участие! Ожидайте, что ее уровень сложности будет выше, чем уровень первых двух олимпиад.

Продолжительность олимпиады – 5 часов, в течение которых вам будет предложено 12 задач. Не забудьте зарегистрироваться на цикл командных интернет-олимпиад в этом сезоне перед началом олимпиады. Обратите внимание, что для участия в командных олимпиадах нужно зарегистрировать именно команду. Команда может содержать от 1 до 3 человек.

Ссылка на регистрацию команд доступна из данного анонса, а также на основном сайте интернет-олимпиад. Всю дополнительную информацию, а также расписание всех предстоящих командных интернет-олимпиад можно посмотреть на той же странице.

Условия появятся на сайте в момент начала олимпиады. Тестирующая система находится по адресу pcms.itmo.ru.

Олимпиаду для вас подготовили студенты/преподаватели Университета ИТМО: Даниил Орешников (doreshnikov), Егор Юлин (EgorUlin), Даниил Голов (DanGolov), Константин Бац (kbats183), Павел Скобелин (pskobx), Антон Вдовин (AVdovin), Артемий Блинов (Blinov_Artemii), Дмитрий Ивченко (dimss) и Максим Альжанов (irdkwmnsb).

Для связи с жюри можно использовать адрес электронной почты iojury@gmail.com.

Удачи!

Hi everyone!

For the Winter 2025 edition of the Osijek Competitive Programming Camp (OCPC), we are working with the National University of Singapore (NUS) to host a mirror of the OCPC in Singapore, during 22-26 Feb 2025. The mirror will consist of 4 training contests, that are a subset of the main 7 contest of the OCPC (scheduled for 15 Feb-23 Feb 2025 in Osijek, Croatia and online, will be officially announced later).

The contest days will be on 22, 23, 25 and 26 Feb, and 24 Feb will be a rest day. The mirror takes place right before ICPC APAC Championship 2025, scheduled for 27 Feb-2 Mar, and is a good training opportunity for its participants. Please note that the mirror is a private initiative of NUS and OCPC, and is not an official part of the ICPC event.

If you want to get a feel of the contests, refer to this comment for past public OCPC contests.

We are still looking for problem-setters for this edition's OCPC. If you are interested in problem-setting, please contact adamant. We are especially interested in problem-setters who can come onsite to give live editorials. Refer to this post for more details.

Registration

The participation fee for the mirror is 50 SGD per person, and it is only possible to participate in person. Please note that it does not include travel, accommodation or meal expenses. If you want to participate, please register here before 10 Feb 2025.

FAQ

Will the contest system be the same as the ICPC APAC Championships?
You will use the same physical set-up, but we will be in a different room in NUS. The online judge used will also very likely be different.

Are teams that are not attending the ICPC APAC Championships allowed to come?
Yes, you are welcome to come.

What is included in the costs?
In addition to the contest system and problems, snacks and a final dinner will be included in the costs. Again, it does not include travel, accommodation or meal expenses.

If you have any other questions, please write them in the comments below!