Hello, Codeforces!

IceBorworntat, NortGlG, omsincoconut, and I are excited to invite everyone to Codeforces Round 1071 (Div. 3), which will take place on 23.12.2025 17:45 (Московское время). You will be offered 8 problems, and you will be given 2 hours and 30 minutes to solve them.

Please note that this contest contains at least one interactive problem and at least one run-twice problem. Please read the guides for interactive problems and run-twice problems before the contest if you are unfamiliar with them.

The round will be hosted by the 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—rank will be determined by number of problems solved, followed by penalty; wrong submissions will incur the usual penalty of 10 minutes, following the rules of educational rounds.

As a reminder, only trusted participants of the third division will be included in the official standings table. This is a compulsory measure for combating unsporting behavior. To qualify as a trusted participant of the third division, you must:

• take part in (and solve at least one problem in) at least five rated rounds
• and not have had 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).

For Codeforces contests—including this one—improper use of artificial intelligence is severely condemned.

We would like to thank:

• sleepntsheep, Marszpace for their problem contributions and valuable help during the preparation of this contest.
• cry for great coordination and support throughout the preparation process.
• MikeMirzayanov for great Codeforces and Polygon platforms.
• temporary1, Friedrich, Intellegent, Argentum47, SpyrosAliv, catgirl, ritam1234, Proof_by_QED, ttamx, tin.le2, Ermiooo159, Mysticmage45, efishel, kwant, simplelife, macaquedev, chromate00, dazlersan1, ALnQ417 for testing the round.
• You for participating in the round.
• blackslex for no particular reason! Really, no reason!

We hope that you guys will enjoy the problems.

Editorial

Salam, Codeforces!

After many years, we are excited and pleased to announce that Codeforces Global Round 31 (Div. 1 + Div. 2) will be held on Dec/19/2025 17:35 (Moscow time). Thanks to XTX Markets for supporting the initiative! In 2025, we held 3 such rounds, and the series results will take into account the best 2 participations out of 3.

Codeforces Global Round 31 marks the third round in the 2025 series of Codeforces Global Rounds. These rounds are open and rated for everyone.

The prizes for this round are as follows:

• The top 30 participants will receive a t-shirt.
• 20 t-shirts will be randomly distributed among participants ranked between 31 and 500, inclusive.

The prizes for the 3-round series in 2025:

• In each round, the top-100 participants get points according to the table.
• A participant's final score will be the sum of the points they earned in their 2 highest-placing rounds.
• The top 20 participants across the series will receive sweatshirts and placement certificates.

We extend our gratitude to XTX Markets for supporting the global rounds initiative in 2025!

The problems for this round were prepared by MohammadParsaElahimanesh, Shayan, and me.

We would like to express our sincere thanks to:

• Akulyat for coordinating the round and providing valuable feedback throughout the process;
• the testers: N_z__, A_G, YuukiS, amirhoseinfar1385, ArshiaDadras, Millad, EyadBT, aimoon, michao, JeffreyLC, s.seraj.shafie, AminAnv1, abramazani, MRasool, Radman_, Hooded_Hood, tilnoene, PMiguelez, chromate00, M.H.N, CLown1331, and dina_saba for their time and effort in testing the problems;
• MikeMirzayanov and KAN for creating and maintaining the great platforms Codeforces and Polygon.

The round will feature 8 + 2 problems, and you will have 2.5 hours to solve them.

Score Distribution: $$$500 - 750 - 1500 - 1750 - 2000 - (2500 - 750) - 2750 - (3000 + 3000)$$$

Good Luck & Have Fun!

Editorial is out.

Congratulations to the winners!

1. ecnerwala

2. Kevin114514

3. kotatsugame

4. maroonrk

5. hos.lyric

6. tourist

7. JDScript0117

8. VivaciousAubergine

9. crazy_sea

10. qiuzx

Привет, Codeforces!

Декабрь — самое время подводить итоги, и мы с радостью приглашаем вас наблюдать за заключительными этапами важнейших школьных и студенческих командных соревнований по спортивному программированию. Помечайте в календариках: с 15 по 17 декабря пройдут 26-я открытая Всероссийская командная олимпиада школьников по программированию и ICPC Northern Eurasia Finals 2025.

Официально открывать чемпионаты мы будем в понедельник 15 декабря, подробное расписание на сайте.

В наших аккаунтах мы будем рассказывать об участниках и их результатах. По традиции мы собрали для вас в одном посте список полезных материалов, которые будут постепенно добавляться, чтобы вы могли удобно следить за ходом соревнований и болеть за фаворитов. Кстати, кто по вашему станет чемпионами ВКОШП и NEF?

ICPC Northern Eurasia Finals

Полуфинальные соревнования ICPC в нашем регионе в этом году отмечают 30-й юбилей — три десятка алгоритмических состязаний, в которых приняли участие тысячи участников, сотни тренировочных контестов, месяцы подготовки, многоступенчатые региональные отборы и яркие, вдохновляющие победы. Какие же юбилейные сюрпризы подготовили организаторы в этом году? Следите за новостями — будет интересно!

В этом сезоне во всех отборочных этапах приняли участие почти 3000 команд, из которых только 341 дошла до Финала Северной Евразии. Посмотреть, как проходили региональные контесты, можно на странице ICPC NERC этого сезона на сайте icpc.global, а также в нашей галерее, где мы собрали фотографии четвертьфиналов и квалификаций. Заодно мы собрали реакции команд из Санкт-Петербурга и Москвы во время четвертьфиналов — их вы можете найти здесь.

Студенческий командный чемпионат, как и все прошлые годы, проходит распределённо в Санкт-Петербурге, Алматы, Новосибирске и Тбилиси. Уже в среду 17 декабря командам предстоит важнейшая интеллектуальная схватка, которая определит финалистов ICPC 2026, представящих Северную Евразию на мировой арене. Место проведения следующего финала пока неизвестно, но с нетерпением ждем анонсов и гадаем о локации.

Для тех, кто не участвует в NEF, будет возможность порешать те же задачи в «зеркале» здесь, на платформе. Регистрация уже открыта!

Присоединяйтесь к трансляции контеста ICPC Northern Eurasia Finals в среду, 17 декабря, в 10:00, а также к трансляции церемонии закрытия, запланированной в 17:00, чтобы узнать всё первыми!

ВКОШП 2025

Во вторник, 16 декабря, пройдёт основной тур школьного командного чемпионата ВКОШП‑2025. По результатам отборов на него приглашены 266 команд. Как и студенческие соревнования, заключительный тур олимпиады распределён по нескольким городам: 156 команд примет «Лахта Холл» в Санкт-Петербурге, 72 команды будут соревноваться в Алматы (Казахстан), 28 команд будут решать задачи в Новосибирске и ещё 10 — в Сириусе.

Основной тур Всероссийской командной олимпиады школьников по программированию, а также трансляция, стартуют во вторник в 10:00 по Москве — присоединяйтесь, чтобы наблюдать за молодыми талантами. Кто же стал чемпионом ВКОШП мы узнаем позднее в этот же день в трансляции церемонии закрытия в 17:00.

Отмечайте в комментариях своих фаворитов и желайте им удачи!

Привет, кодефорсес ₍^. .^₎⟆

Я, ABalobanov и Slamur рады пригласить вас поучаствовать в Codeforces Round 1070 (Div. 2). Он состоится в 11.12.2025 17:35 (Московское время). Раунд будет рейтинговым для всех участников с рейтингом строго меньшим 2100. У вас будет 2 часа, чтобы решить 6 задач.

Мы хотим выразить благодарность этим замечательным людям

• Самому милому координатору FairyWinx.
• KAN, MikeMirzayanov за платформы Codeforces и Polygon.
• Нашим восхитительным тестерам:
• Красночерное тестирование: Um_nik.
• Красное тестирование: A_G, Wansur, OG_Matveychick1, __baozii__, JoJo.
• Оранжевое тестирование: aimoon, fractal, AlexanderGarifullin, Nyatl, antonis.white.
• Фиолетовое тестирование: dmkozyrev, yanb0, KiruxaLight, wuhudsm, Mosyagin.
• Синее тестирование: InsomniaT, atayawa, void_slowdown, kenzhik, rockoff, agaforces, R1nixi.
• Зеленое тестирование: emirhanbanan, ad1let17.

Разбалловка:

Надеемся, вам понравятся задачи!

UPD: Разбор

Hi Codeforces!

On Dec/06/2025 11:15 (Moscow time) we will hold Codeforces Round 1069 (Div. 1) and Codeforces Round 1069 (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 2025, Algorithms track, that will be held at the same time.

The problems are authored by v_vsg, heesooyaam, teraqqq, LeoPro, isaf27, elshiko, Flyce with guest problems from napstablook, sunkuangzheng, and great help from Vladithur, Dominater069, and tourist.

I'd like to thank Um_nik, Akulyat, okwedook, Merkurev, conqueror_of_tourist, Dominater069, cadmiumky, OG_Maksimchick4, Iguanado for testing the round, and MikeMirzayanov for the Polygon and Codeforces systems.

Because the 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.

P.S. Same as with many rounds based on onsite contests, you can expect that the difficulty curve may be different from the one typical for Codeforces rounds. This is mostly connected with the limited amount of testing we can do to avoid problem leakage, and with the limited choice of problems. Nevertheless, I believe that it's better to have a round than not have one, and I hope you'll enjoy the problems!

Good luck!

Scoring distribution: you'll see in the contest.

UPD: there is live stream with problem discussions and comments here: https://www.youtube.com/watch?v=6R7iwYAXKLY

UPD2: Editorial.

Hello Codeforces!

We are glad to invite you to participate in Codeforces Round 1068 (Div. 2) on Dec/05/2025 17:35 (Moscow time).

This round is rated for all participants with rating below 2100. You will be given 6 problems and 2 hours to solve them. At least one problem will be interactive, so please make sure to read the guide for interactive problems before the contest.

In this contest, characters from four different anime series appear in some of the problem statements (including the one my avatar is from). Can you guess which series they are?

We would like to thank:

• paulzrm, HHH666666, chen_zida and HugeWide for writing the problems.

• Error_Yuan for coordinating the round.

• MikeMirzayanov for great Codeforces and Polygon platforms.

• Alexdat2000 for translating the statements into Russian.

• 0htoAi, A_G, Arpa, Caylex, Kowngx, Mitsukasa_Ayase, NanamiChiaki_, ShmilyTY, TKXZ133, Unlimited_zero, _istil, liruisi, real_Catalan1906, rui_er, temporary1, wuhudsm for testing the round (sorted by dictionary order).

• You

  for participating in this round.

The score distribution will be announced later.

Good Luck & Have Fun!

UPD1: Score Distribution: 500 — 1000 — 1250 — 1750 — 2250 — 3000.

UPD2: In this round, hacks will be disabled on problems A, B, C, D, and E. We will have pretests = systests in these problems. Hacks will be enabled on F as usual, and we will have systests = pretests + hacks.

UPD3: The editorial is out.

UPD4: Congrats to the winners!

Div. 1:

• maspy
• zltzlt
• TKT_YI
• ItsNotMeItsYou
• Egor

Div. 2:

• Anlybt
• IHaveInt (disabled)
• votranngocvy
• omoch1
• cgmoreda
• DSCS2009

Hi everyone!

Supported by

The OCPC (Osijek Competitive Programming Camp), an award-winning camp for university students to prepare for ICPC and other coding competitions, is back again this winter, on January 24 — February 1, 2026!

The camp is organized by adamant and -is-this-fft- on the premises of the University of Osijek in Osijek, Croatia.

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.

Details

The participation fee for both online and onsite participants is 198€ per team.

Similar to previous camp editions, the fee does not include regular meals, travel or accommodation.

We support and empathize with those affected by the ongoing war in Ukraine, therefore we offer a free participation for affected individuals and teams affiliated with Ukrainian institutions.

Additionally, we would like to offer the following discounts:

• Early bird discount: We offer a reduced participation fee of 147€ per team if you register before December 17, 2025.
• Hardship discount: We offer fee reduction to 99€ per team, on request, if you feel that default fee makes it a financial burden for you.

We do not require any proof or documentation when using the hardship option, and trust your self-assessment. Nevertheless, we ask you to be mindful when using it, as we still have to rely on participation fees as the baseline for running the camp.

The expected starting time for the contests is 10am CET. For remote participants, it is still a preferred starting time, but we will make accommodations for virtual participation at a later time, when necessary.

Most of our contests are originally developed for the camp. A small number of contests may be based on previous contests that have not been released to the general public. If you have seen some problems of a contest before, you can't participate on that day. We will privately contact participants who might be affected.

After the camp, we will have a silence period during which camp materials will not be released to the public. We ask participants not to discuss the problems in public unless they obtained an explicit permission from contest authors.

If you would like to get a feel of the contests, you can find links to some of the previously published camp contests here.

If you have any questions about the camp, please feel free to send us an email, or join our Discord server!

Participants

If you are interested in participating, please fill the form here.

Register before December 14, 2025 to receive an early bird discount!

We ask you to register before January 17, 2026 if you want to participate remotely and before January 10, 2026 if you want to participate in Osijek. If you require a visa, please register as soon as possible, as it might take a few weeks to receive (depending on your location).

If your university or organization has a lively ICPC community that may be interested in attending the camp, and you have some contacts of people in charge (e.g. coaches) we would highly appreciate if you could share some details in a direct message to me. Thanks!

Problem authors

We'd like to thank and praise the authors of the contests in the camp:

• AmirrzwM — ICPC World Finalist (2024, 2025), author of Codeforces and Rayan Rounds, and INOI (Iranian National Olympiad in Informatics) Silver Medalist.
• MohammadParsaElahimanesh — Author of Codeforces and Rayan Rounds, INOI Silver Medalist, and top problem solver on Quera.
• Arpa — two times ICPC World Finalist and former Codeforces Contest Coordinator.
• -is-this-fft- — ICPC 2019 world finalist, Google Hash Code 2020 finalist.
• Pyqe — IOI gold medalist, author of IOI 2024 Nile and Tree.
• Kinon — IMO bronze, silver, and gold medalist.
• gloria_mundi, burg113 — 2025 GCPC winners, 2024 and 2025 NWERC silver medalists.
• Yixiong — Problemsetter for ICPC Asia East contests. Universal Cup Staff.
• Claris — ICPC 2017 and 2018 world finalist. Top contributor of QOJ.
• marks39, ssk4988 — 2025 North America Big South champions, participants in the 2025 NAC and WF. Currently coaching for UCF.
• KCPC — A Competitive Programming Club of Kyoto Univ, which is a regular at the WF.

You can find more details about contest rules and technical setup on the website.

Special thanks

Finally, we say special thanks to

• our sponsors, who make the camp possible;
• ICPC foundation for their help and support;
• Codeforces for support and guidance;
• eolymp for providing an online judge for the contests;
• Mathos for the invaluable help and providing a physical location for the camp.
• BigBag for consistently making very useful combined scoreboards at https://acmallukrainian.ho.ua/camps/.

UPD: The contest platform is up! Everyone can now register through the platform!!!!

UPD: The champion will be invited as a guest (with full accommodation and travel expense covered) to the 2026 Universal Cup Finals. The champion will be awarded at the time and will be invited to participate in the onsite challenge.

Hello Codeforces! We are very happy to announce that, after months of preparation, we have finally scheduled our first online challenge from December 17th to December 24th! Sponsored by Huawei, we have prepared valuable prizes for everyone to compete for! Although many details are still to be finalized, we are too excited to share the following details with you as an early Christmas gift!

• Contest Name (Subject to Change): The 2025 Universal Cup Online Challenge Sponsored by Huawei

• Platform: Universal Cup Challenge Platform (Powered by Hydro）

• Date: December 17th &mdash 20:00; December 24th 20:00（UTC+8)

• Prize:

As always, the Universal Cup is dedicated to bridging the gap between the competitive programming community and the industry. This online challenge is an attempt that we are counting on. We will do our best to make it as good as possible, and we call on everyone to support this challenge by participating!

Since we hope everyone to focus on the challenge, there will be no regular stage on December 21st. The registration details will be announced in early December. We will be posting another blog (on Codeforces, the Official Website, and other threads) to specify the rules. Please stay tuned!

To learn more about Universal Cup, please visit our official website. The 4th season is ongoing now.

The Universal Cup is sponsored by

Good day Codeforces ✨

We are excited to invite you all to Codeforces Round 1067 (Div. 2), starting at Nov/29/2025 17:35 (Moscow time).

This round features 6 problems to be scored in 2 hours, with a few problems including multiple parts. All tasks were authored and prepared by koderkushy and me. This round will be rated for all participants with rating below 2100. Take a look at all the problems, we hope you enjoy the challenge! 🚀

We extend many thanks to our team for helping make this round possible:

• abc864197532 for his excellent coordination.
• KAN for preliminary review.
• Testers lineup: Dominater069, dreamoon_love_AA, Fysty, amano_hina, _istil, __baozii__, IceKnight1093, CoderAnshu, Pols_Agyi_Pols, sv1shan, piyush_pransukhka, a.out, BiggestOtaku, Bucketsmith, -firefly-, satyam343, plAtEaUpUs, omsincoconut, snasibov05, homelanderrr, _helloLad, BladeRunner, deneribeiro10, Rafio, balakrishnan, UniversalAdmin
• Alexdat2000 for translation problem statements into Russian.
• MikeMirzayanov and KAN for lovely platforms Codeforces and Polygon.
• And of course, you, for taking part! 💛

Score Distribution: $$$500-1250-1500-2000-2750-(2500+1000)$$$ 🏆

UPD: Congrats to the winners!

• 🥇 StarSilk
• 🥈 Noobish_Monk
• 🥉 Mon_ster
• BurnedChicken
• ec3e9a2e8e

Kudos to antontrygubO_o for almost getting to the intended solution of F2 in contest!

UPD 2: The editorial is out.

Привет, Codeforces!

Благодаря поддержке Neapolis University Pafos, продолжается серия образовательных раундов.

В Nov/28/2025 17:35 (Moscow time) состоится Educational Codeforces Round 185 (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, Максим Neon Мещеряков, Роман Roms Глазов и Максим FelixArg Новоточинов. Также большое спасибо Михаилу MikeMirzayanov Мирзаянову за системы Polygon и Codeforces.

Удачи в раунде! Успешных решений!

UPD: Разбор опубликован