Nihao! Hello to all fans of competitive programming and Codeforces enjoyers!

On behalf of Tsinghua University’s Zhili College, we — your proud and slightly sleep-deprived Class of 2028 Information and Computing Science students — are happy to invite you to participate in Codeforces Round 1010 (Div. 1) and Codeforces Round 1010 (Div. 2), which will take place on Mar/15/2025 08:35 (Moscow time). Note the unusual start time of the round.

You’ll have 3 hours to tackle 7 problems for division 1 and 6 problems for division 2, the round will be rated for all participants. It’s a little longer than your typical Codeforces round, and yes, we know you’ll be sleep-deprived — but who needs sleep when there’s coding to do, right?

This round’s problems are brought to you by the incredible Ecrade_, newbiewzs, chen_03, 18Michael and sunzh. Special thank you to dapingguo8, Zesty_Fox and Iam1789 who also prepared problems that were ultimately not used in this round.

A massive THANK YOU to the following legends who made this event possible:

• The one and only KAN for his invaluable support in hosting the round.

• Our chad coordinator, FairyWinx for coordinating this round, finding testers, and providing moral and technical support.

• Our brilliant testers: Zesty_Fox, peiwenjun, Iam1789, chen_03, wangjinbo, sunzh, exxqfu, li0201. peop1e_, I_love_kirill22, RP-1, TeaTime, turmax for testing and providing invaluable feedback.

• Our fantastic organisers: HeziCyan, Iam1789, cszyf, and KaiSuoShuTong for the smooth operation of the contest.

• Our advisors zhou888, RegisterName, Yijie Wang and Xi Wang from Zhili College for supporting our efforts and ensuring school approval.

• Big shoutout to DreamingRabbit, president of Tsinghua University’s Association of Algorithmic Competitions, for his steadfast support and unwavering determination in helping us turn this dream into a reality.

• MikeMirzayanov and geranazavr555 for enabling this event through the amazing Codeforces platform.

Zhili Cup itself is an annual event hosted by Tsinghua University’s Zhili College along with its freshmen of ICS. We are delighted to meet you on Codeforces this year.

Good luck, and may your code be bug-free and your coffee cup never empty.

See you at the round!

UPD: Here comes the scoring distribution.

Division 1:

Division 2:

Oh hello there. This is chromate00, just casually on the announcement of Codeforces Round 1009 (Div. 3). And now, you see a drawing.

$$$\square$$$ — $$$\triangle$$$ — $$$\triangle$$$ — ◯ — $$$\triangle$$$ — $$$\square$$$ — $$$\triangle$$$

And then, you think. You see a square, a triangle, and a circle. Also, a Korean problemsetter. You immediately imagine the certain survival game that popped up in your memory. And you may be right. Or you might be wrong. Whatever, what I can ensure you is that you will be absolutely stunned to see the problems. Or astonished. You might not believe what you see. This round might change everything.

Anyways, the preface was a bit too long. Starting from Mar/11/2025 17:35 (Moscow time), you will be given $$$\mathbf{7}$$$ problems to be solved in $$$\mathbf{2.5}$$$ hours. There is at least one interactive problem, so I strongly urge you to read the guide if you are unfamiliar with the format.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, all solutions will be judged on preliminary tests during the round, and after the round, there will be a 12-hour phase of open hacks. After the open hack phase, all accepted solutions will be rejudged on successful hacks. Also, note that there is no score distribution but the usual penalty of 10 minutes for each wrong submission, following the rules of educational rounds.

Remind yourself that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

• take part in at least five rated rounds (and solve at least one problem in each of them)
• not have a rating of 1900 or higher at any moment in time.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you (unless you register unrated).

Also, note the (relatively recent) rule restricting the use of AI. If you are caught while breaking this rule, you will be terminated.

This round is made possible by the help of the following people:

• cry and Vladosiya for coordinating the round (and translating the statements),
• Proof_by_QED for reviewing the tasks (and not so particularly testing them),
• Our army of (not so) pink soldiers: Intellegent, amoeba4, mathtsai, Error_Yuan, temporary1, Edeeva, yeetholmes619, hashman, larush, poi, (VIP) Dominater069, (VIP) LMeyling, (VIP-) macaquedev, antontrygubO_o, Mercuria, DivinePunishment, 0pt1mus23, pianapolataa, reirugan, efishel, (VIP) awesomeguy856, rewhile, __baozii__, yoru_sacri, -firefly-, sbreger60, monadtransformer, Rahuldeb5,
• The VVVIP, MikeMirzayanov, for great platforms Codeforces and Polygon.

I hope that you will also be in the spectacular moment.

UPD: Editorial has been posted.

UPD2: Congratulations to the top participants!

All participants:

1. ksun48
2. arvindf232
3. StarSilk
4. maspy
5. risujiroh

Trusted (rated) participants:

1. sharvil_cpp
2. Xing_Kong_C
3. jxu
4. 1zaid1
5. eysikingE

Hello, Codeforces!

I'm glad to invite everyone to Codeforces Round 1008 (Div. 1), Codeforces Round 1008 (Div. 2), which will be held on Mar/10/2025 17:45 (Moscow time).

You will be offered $$$7$$$ problems in both divisions 1 and 2, and you will be given $$$2$$$ hours and $$$30$$$ minutes to solve them.

Both divisions contain at least one interactive problem(s). Please look up the guide if you are unfamiliar with them.

I'd like to give my utmost thanks to

• satyam343 and Kaey for coordinating this contest, preparing statements/tasks, and donating a problem.

• The testers: Dominater069, LMeyling, Rhael, Mysticmage45, tigerBoss101, Non-origination, TyroWhizz, _istil, LipArcanjo, Error_Yuan, Proof_by_QED, ffao, NerfThis, ikrpprppp, Murinho, WLZ, Irmuun.Ch, Tainel, Chaska, marianoferesin, ankan2526, Darshan_Bhangale, kolomig0r, dougalves, profchi, Lucina, 0I0acOJleHbKa, Marckess, Saman., N_z__, PeruvianCartel, sammyuri, A_G, catology, arvindf232

• My friends Rhael for an illustration, Punpun (no CF account) for one task, and a shoutout to Mysticmage45 for no particular reason.

• Alexdat2000 for the Russian translation.

• MikeMirzayanov for Polygon and Codeforces platforms.

I hope everyone will indulge in the tasks blissfully.

Score distribution

Division 1: $$$500-1000-1500-2250-2250-2500-3000$$$

Division 2: $$$500-750-1250-1750-2000-2750-3500$$$

Congratulations to the winners!

Division 1

1. jiangly

2. Ormlis

3. Um_nik

4. tourist

5. ksun48

Division 2

1. a1048576

2. SussykinWantsNatalia

3. DanielAnker

4. Manasvi

5. hungpc1577

Editorial

Welcome to the final weekend of Codeforces Blitz Cup! More information about selection matches is available in this post, but we are now down to just 16 contestants! Here is how they will compete on Saturday and Sunday for the content and glory!

Saturday, March 8

1. turmax 25 : 20 b6e0: 08.03.2025 13:00 (Московское время) Scoreboard
2. errorgorn 31 : 2 izban: 08.03.2025 14:10 (Московское время) Scoreboard
3. isaf27 2 : 31 alireza_kaviani: 08.03.2025 15:00 (Московское время) Scoreboard
4. winners of 1 and 2: errorgorn 20 : 25 turmax: 08.03.2025 16:00 (Московское время) Scoreboard
5. Geothermal 35 : 10 jonathanirvings: 08.03.2025 17:00 (Московское время) Scoreboard
   ☕

6. heuristica 0 : 33 antontrygubO_o: 08.03.2025 19:00 (Московское время) Scoreboard

7. tourist 31 : 2 conqueror_of_tourist: 08.03.2025 20:00 (Московское время) Scoreboard
8. ksun48 20 : 13 Kuroni: 08.03.2025 21:00 (Московское время) Scoreboard
9. winners of 6 and 7: tourist 45 : 0 antontrygubO_o: 08.03.2025 22:00 (Московское время) Scoreboard
10. Golovanov399 33 : 0 induk_v_tsiane: 08.03.2025 23:00 (Московское время) Scoreboard

Sunday, March 9

• 11: winner of 3 and 5: alireza_kaviani 10 : 35 Geothermal: 09.03.2025 15:00 (Московское время) Scoreboard
• 12: winner of 8 and 10: ksun48 15 : 18 Golovanov399: 09.03.2025 16:00 (Московское время) Scoreboard
• 13: Semifinal: winner of 4 and 11: turmax 12 : 21 Geothermal: 09.03.2025 17:00 (Московское время) Scoreboard
• 14: Semifinal: winner of 9 and 12: tourist vs Golovanov399: 09.03.2025 18:00 (Московское время) Scoreboard Scoreboard2
• 14 rematch: tourist 27 : 18 Golovanov399: 09.03.2025 19:20 (Московское время) Scoreboard
• 15: Final match: winner of 13 and 14: tourist 45 : 0 Geothermal: 09.03.2025 20:05 (Московское время) Scoreboard

And the winner is

Congratulations tourist on winning the Blitz Cup 2025!

And huge thanks to lperovskaya, Vladosiya, tourist, MikeMirzayanov for organizing the event, as well as Egor and jonathanirvings for commentating most of the matches!

Tune into the live broadcast on youtube.com/@codeforceslive to see your favorite contestants compete and commentate!

Всем привет!

На днях состоится Открытая олимпиады школьников по программированию, которая может быть вам знакома по зеркалу прошлого года или по раундам 345, 469, 545, 626, 707, 775. Олимпиада была подготовлена Московской методической комиссией. Архивы прошлых лет, задачи отборочных этапов и другую информацию можно посмотреть на сайте олимпиады inf-open.ru.

Открытая олимпиада составляется из интересных и сложных задач, которые были предложены многочисленным коллективом наших авторов, поэтому мы решили провести нерейтинговое зеркало олимпиады на Codeforces. Олимпиада проходит в два тура, каждый из которых состоит из $$$4$$$-х задач, неупорядоченных по сложности, и $$$5$$$ часов на их решение. Сложность задач сопоставима с уровнем Div. 1. За каждую задачу можно получить до $$$100$$$ баллов, которые распределены по нескольким подзадачам с различными ограничениями, что позволяет участникам получить частичные баллы. Оценивание происходит по формату IOI, где участник получает полный отчёт по тестированию по всем тестам Online-подгрупп во время соревнования. Особенностью открытой олимпиады является то, что в некоторых задачах присутствуют Offline-подгруппы, результат по которым будет доступен только после конца соревнования. Обратите внимание, что во время соревнования вам не будет доступна таблица результатов.

Зеркало на Codeforces состоится в 07.03.2025 11:05 (Московское время) и 10.03.2025 11:05 (Московское время).

Задачи соревнования были придуманы и подготовлены Kapt, allvik66, stepanov.aa, Mangooste, AgafonovArtem, dyrbulshchyl, RP-1, valerikk, yunetive29, Kniaz, Alexdat2000 под руководством Mangooste, grphil и Андреевой Елены Владимировны. Также выражаю большую благодарность Tikhon228 за вклад в подготовку задач.

Отдельное спасибо MikeMirzayanov за системы codeforces и polygon, который использовался при подготовке задач этой олимпиады.

Большое спасибо тестерам олимпиады: Ormlis, isaf27, allvik66, AgafonovArtem, RP-1, Qwerty1232, kostylevGO, katyaporay, FairyWinx, a.stepanov281005, EgorUlin, pakhomovee, ArtAlex, Sweezy, Be_dos, valerikk, alexsushin, Dart-Xeyter, yunetive29, AndreyPavlov, Mikhango, v0s7er.

Всем удачи!

UPD1: Доступны результаты первого дня.

Всем привет!

23 марта 2025 года состоится финал ИОИП-2025. Эта олимпиада является личным зачетом "Олимпиады школьников по информатике и программированию" (ее командным зачетом является ВКОШП), которая входит в перечень олимпиад Российского совета олимпиад школьников и имеет 1 уровень. Таким образом, диплом этой олимпиады может давать льготы при поступлении в вуз.

На заключительный этап без дополнительного отбора приглашаются участники заключительного этапа ВКОШП 2024, обучающиеся в выпускном классе, все участники муниципального этапа ВсОШ в Санкт-Петербурге, обучающиеся в 11 классе, которые набрали на муниципальном этапе хотя бы 300 баллов, а также участники, набравшие хотя бы 150 баллов на первом или 146 на втором отборочном этапе.

Финал пройдет в очном формате на множестве точек проведения http://neerc.ifmo.ru/school/ioip/contacts.html, список пополняется до 15 марта могут появиться еще точки проведения.

Если вы имеете право принять участие в финале, регистрируйтесь на сайте http://neerc.ifmo.ru/school/ioip/ до 20 марта. Для получения оперативной информации об олимпиаде вступайте в телеграм-канал https://t.me/itmo_ioip

Всем удачи!

We’re excited to launch the first-ever Midnight Code Cup (MCC) — a team competition featuring an online Qualification round and a 24-hour onsite Final. Expect algorithmic challenges, optimization puzzles, cutting-edge computer science, and some just plain weird problems. It’ll be exhausting. And fun.

Who are we?

A team of problem solving geeks veterans enthusiasts, eager for the return of this contest format. The idea of Midnight Code Cup was born at Recraft.AI (AI image generation and graphic design pioneers) with huge support from JetBrains (creator of Kotlin, intelligent IDEs, and AI-driven developer tools) as well as Neon (developer-first open-source database) and Pinely (HFT company powered by competitive programmers).The sponsor list is not final and will be updated.

We are also thankful to have Codeforces as our hosting partner.

Who can participate?

Teams of 3 ready to rock and roll! No programming language, affiliation or problem solving methods restrictions. You only need to be at least 18 years old and have a slightly concerning enthusiasm for coding challenges.

Save the Date

April 12, 2025: Online Qualification (4 hours) – here at Codeforces, starts at 13:00 UTC

June 7–8, 2025: Onsite Final (24 hours) – Belgrade, Serbia

Problem setters and jury: Aksenov239, isaf27, NALP, Taube, Gassa, cdkrot, PavelKunyavskiy, tourist, qwerty787788, MaxBuzz, pvs, Solenoid555, nsychev, naagi

Registration opens soon – you have enough time to find a team. Leave your email here and you will be the first to register.

See you at Midnight!

Update: We've set the start time for the qualification round (13:00 UTC). The duration has been changed to 4 hours to accommodate participants across multiple time zones, although covering all regions globally remains a challenge.

The European Championship 2025 will take place on the 2nd of March in Porto. The top teams from the European ICPC regionals CERC, NWERC, SEERC, SWERC will compete for the title of European champions. It is the second edition of this ICPC super-regional.

The mirror contest European Championship 2025 - Online Mirror (Unrated, ICPC Rules, Teams Preferred) will be held on Codeforces at Mar/02/2025 13:35 (Moscow time) and will last 5 hours.

The mirror contest will feature the same problems as the official competition, except for one problem, which will be presented in a more challenging version.

I am the chief judge for the competition and I want to thank:

• The amazing set of judges who proposed and prepared the problems: bicsi, cip999, cdkrot, Egor, gangsterveggies, Giove, Jorke, Petr, thocevar.
• Our beloved tester ksun48.
• Everyone involved in the organization of EUC, in particular our director Fernando Silva.
• The developers of DOMjudge, the contest system used in the official contest.
• MikeMirzayanov for Polygon (that we used to prepare the problems) and for letting us host the mirror on Codeforces.

I invite you to participate in the contest and I hope that you will like the problems.

On the difficulty
The contest features problems with difficulties from div1A to div1E. It should be enjoyable for many, and interesting even for the strongest teams in the world.

Rules

1. The contest is unrated, so your codeforces rating will not be affected.
2. The scoring is ICPC-style: teams are first sorted by number of problems solved, then the time-penalty is used as a tie-break. An incorrect submission gives a 20 minutes penalty.
3. We encourage participation as a team.
4. If you are participating in a team, we encourage you to use only one computer for coding the solutions (as in an ICPC contest). Regarding using templates, googling, and copy-pasting code: feel free to do it.

UPDATE 1: Here you can find the editorial: https://codeforces.me/blog/entry/140239

UPDATE 2:

Congratulations to the winners, and especially to the first team for AK:

1. [?]: LeoPro, fastmath, turmax
2. jiangly
3. [HoMaMaOvO] hos.lyric, maspy, maroonrk

Hi,

We would like to invite you to participate in the live online mirror contest of The 2025 ICPC Asia Pacific Championship next weekend. ICPC Asia Pacific Championship is the contest for top non-winning teams from all regional contests in the region to qualify to the World Finals. See the region rules and competition page for more details.

The official contest is scheduled to start at Saturday, 1 March 2025, 10am (UTC+8). The live online mirror contest is scheduled to start only 5 minutes later, to keep both contests run almost in sync. The contest is 5 hours long and consists of several problems.

Please note that we might have to postpone the live online mirror contest in case the official contest is delayed. This is to the ensure that the tasks are not available to the public until the official contest starts.

The contest will use ICPC-style scoring (same as the official contest) and will be unrated. You can participate as an individual or as a team, although as a team of three members is preferred.

See you on top of the leaderboard.

The 2025 ICPC Asia Pacific Championship Judges

[UPD]: Task analysis: https://apac.icpc.global/assets/competition/problem-analysis.pdf

Всем привет!

В ближайшую субботу, 1 марта 2025 года в 15:00 состоится третья личная интернет-олимпиада для школьников. Эта олимпиада является тренировочной и не влияет на проход на ИОИП.

Все материалы по второй интернет-олимпиаде станут доступны завтра. Проходные баллы со второго отбора на ИОИП также будут выложены на сайте в ближайшие несколько дней. Форма регистрации на финал для прошедших будет отдельной от регистрации на Интернет-олимпиады, следите за обновлениями на странице ИОИП.

Продолжительность олимпиады — 5 часов. Не забудьте зарегистрироваться на цикл личных интернет-олимпиад в этом сезоне перед началом олимпиады. Обратите внимание, что для участия в личных олимпиадах, нужно зарегистрировать участника (по ссылке "Новый участник"). Дополнительную информацию, а также расписание всех предстоящих интернет-олимпиад можно посмотреть на страничке интернет-олимпиад.

Условия появятся на сайте в момент начала олимпиады, а также на вкладке "Файлы" в тестирующей системе. Тестирующая система находится по адресу pcms.itmo.ru.

Олимпиаду для вас подготовили Даниил Орешников (doreshnikov), Даниил Голов (DanGolov), и Константин Бац (kbats183).

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

Удачи!