Привет, Codeforces!

Мы рады позвать вас на Codeforces Round 1076 (Div. 3), который пройдет в 25.01.2026 17:35 (Московское время). У вас будет ровно 2 часа и 15 минут для решения 7-8 задач. По крайней мере одна задача будет интерактивной, поэтому мы настоятельно рекомендуем прочитать руководство по интерактивным задачам перед соревнованием.

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.

Напоминаем, что в официальную таблицу результатов будут включены только достоверные участники третьего дивизиона. Это обязательная мера борьбы с неспортивным поведением. Для квалификации в качестве достоверного участника третьего дивизиона необходимо:

• принять участие (и решить хотя бы одну задачу) как минимум в пяти рейтинговых раундах
• и не иметь рейтинга 1900 или выше в любой момент времени.

Независимо от того, являетесь ли вы доверенным участником третьего дивизиона или нет, если ваш рейтинг меньше 1600, то раунд будет для вас рейтинговым (если только вы не зарегистрируетесь без рейтинга).

Задачи были придуманы и подготовлены: KluydQ, YF_YUSUF, Wansur, Mendeke.

Отдельную благодарность хотелось бы выразить:

• Vladosiya и soullless за координацию раунда и за возможность провести его.
• Wansur, k1r1t0, Arpa, Aldk, SorahISA, QazLon, itz_pabloo, YF_YUSUF, Daki-sa, Yessimkhan, Arkanefury, hamburger46, gbula, China001, Dobri_oke, Idam, wadibay, Darko, uwbt17, raiywbek, CLown1331 за уделение времени и тестинг.
• MikeMirzayanov и KAN за замечательные платформы.

UPD: Разбор по ссылке

Привет, Codeforces!

Мы очень рады анонсировать, что Codeforces Round 1075 (Div. 2) пройдет в 23.01.2026 17:35 (Московское время). Раунд будет рейтинговым для всех участников с рейтингом строго меньшим $$$2100$$$. У вас будет $$$2$$$ часа, чтобы решить $$$6$$$ задач, некоторые из которых разделены на подзадачи.

Раунд основан на Международной Олимпиаде по Геометрии имени Шарыгина Все задачи придуманы и подготовлены yanb0, furt1ve и мной.

Мы хотим выразить специальную благодарность этим замечательным людям:

• Akulyat за координирование раунда и помощь в подготовке задач;
• Тестерам: Wansur, __baozii__, k1r1t0, Mark_Pr, _istil, OG_Matveychick1, TimDee, zhenja, abs0lute, princeee, NotDWT, Sokol080808, machine_solution, Pobe, madlogic, wuhudsm, pattern-seeker, dvb1r, VitaliiV, penwick, sanya37y, itz_pabloo, Morselllprimo, AK_15, Golden_Square, Norman165, arsen1y, graphs_enjoyer, tih-a, emirhanbanan, ak1ko, s97b, thereverberation, bibiq за их время и усилия, потраченные на тестирование задач;
• MikeMirzayanov and KAN за замечательные платформы.

Разбалловка:

$$$500-1000-(1250+750)-(2000+750)-2500-3250$$$

GLHF!

UPD1 Раунд завершен, спасибо за участие.

UPD2 Разбор

UPD3 Winners and First to solve

Div2

Div1 + Div2

First to solve

Открыта регистрация на 50-е международные тренировочные студенческие сборы по программированию в Петрозаводске.

СБОРЫ ПРОЙДУТ В ОНЛАЙН + ОФЛАЙН РЕЖИМЕ с 29 января по 06 февраля 2026 года.

Для команд из ЕАЭС возможно участие офлайн, подробности в информационном письме.

К участию приглашаются команды из студентов от 1 до 3 человек.

Уровень задач сборов: для участников полуфинала и финала чемпионата мира ICPC.

Расписание сборов состоит из 8 контестов и одного дня отдыха между ними, предварительное расписание сборов: camp.icpc.petrsu.ru/2026w/schedule

Для каждого контеста будет организована трансляция разбора на английском языке.

Организационный взнос за одного человека (для участников из стран ЕАЭС) зависит от выбранного варианта:
- Очное участие с трехразовым питанием в кафе ПетрГУ – 24 400 рублей.
- Очное участие без питания – 13 420 рублей.
- Онлайн участие – 12 200 рублей.

Оргвзнос за участие в сборах для участников из остальных стран составляет 165 долларов за одного человека.

Для регистрации тренеру команды следует написать письмо организаторам.
После согласования каждому участнику команды необходимо пройти индивидуальную регистрацию на сайте сборов.

Контактная информация

• Связь с организаторами: [email protected]
  
• Сайт сборов: camp.icpc.petrsu.ru
  
• Группа сборов в ВК: vk.com/camp_acm_petrsu
  

Hello Codeforces!

I am delighted to invite you to the first Div. 4 round of the year: Codeforces Round 1074 (Div. 4)! The round is scheduled for Jan/18/2026 17:35 (Moscow time). You will be given 7 — 8 problems to solve (all authored by me), and 2 hours and 15 minutes to solve them.

The format of the event will be identical to Div. 3 rounds:

• 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 will be recalculated.

Only trusted participants of the fourth division will be shown in the official standings. To be a trusted participant, you must:

• have participated in at least 5 rated rounds where you have solved at least one problem.

• have a rating less than 1400.

Regardless of if you are a trusted participant or not, this round will be rated for you if you

• have a rating of less than 1400 or are unrated.

• do not select the "Register as unrated" option when registering for the contest.

Participants who are rated 1400+ are not allowed to create a new account for the purpose of competing officially. We encourage you to take part unofficially.

We would like to remind all participants about the rule against using artificial intelligence tools during the contest. Violators will be sent to cry's basement; we spent a long time expanding it so we could host this round, and we sincerely hope that it won't be filled back up again.

I would like to thank:

• cry for being an incredible coordinator, and for giving me a chance to write this contest.

• Vladosiya for translating the problems into Russian.

• cduckling for looking over the initial problemset before I officially proposed it.

• Our red testers: __baozii__, Intellegent

• Our golden testers: Arpa, -firefly-, AksLolCoding, Edeeva, Friedrich, omsincoconut, Proof_by_QED, temporary1

• Our purple testers: macaquedev, pop, tin.le2, wuhudsm

• Our blue testers: apollo07, Argentum47, Eikyu, Ermiooo159, expertaq, Jteh, ritam1234, simplelife, SpyrosAliv, susvent, Vladosiya

• Our cyan tester: anandswaroop191

• Our gray testers: DraxLab, piman51277

• Our unrated tester: qdread

• MikeMirzayanov for creating Codeforces, Polygon, and testlib.h.

• You, for participating!

I wish you all the best of luck in this competition, and I hope you enjoy the problems!

EDITORIAL.

Hello Codeforces,

After decades of hard work and several quality reviews from independent third parties, I'm delighted to invite you to participate in Codeforces Round 1073 (Div. 1), and, if you really want to, Codeforces Round 1073 (Div. 2), which will both held on 17.01.2026 17:35 (Московское время).

In each division, you will be given $$$7$$$ problems and $$$3$$$ hours to solve them, one of which will be divided into subtasks. Problems were mainly authored by me, nifeshe, with help from nika-skybytska and satyam343. Only $$$6$$$ or $$$7$$$ problems will not be interactive in each division, so please make sure to read the guide for interactive problems before the contest.

In related news, we’ve already been awarded the Nobel Peace Prize for this round, for achieving a level of problem quality so universally accepted that all global conflicts have been resolved.

I would like to thank the following people for making the contest possible:

• satyam343 for outstanding coordination and helping with problem ideas/preparation.
• Um_nik for preliminary reviewing the round.
• Sana for being the most helpful tester I've ever seen.
• EvenImage, Geothermal, A_G, sammyuri, _istil, Intellegent, catgirl, Dragos, weirdflexbutok, Hori, samsoom, whiitex for VIP testing.
• The rest of our testers: LipArcanjo, Adam_GS, __baozii__, jiazhichen844, maomao90, IceKnight1093, wangmarui, caterpillow, -firefly-, arvindr9, djm03178, omsincoconut, CatsAreCool, reirugan, conjectureguy, SpyrosAliv, chromate00, Non-origination, beaten_by_ai.
• Alexdat2000 for translating the problems to Russian.
• MikeMirzayanov and KAN for the Codeforces and Polygon platforms.
• And You for participating!

The score distribution is below.

Div. 1:

Div. 2:

Unlike other rounds, this one will only be held once, so I sincerely hope you will not skip the round and enjoy all of the problems.

UPD 1 The hacks are disabled for problems A — D2 in Div 2, and for problems A — B2 in Div 1. We have final tests consisting of pretests and hacks for all problems.

UPD 2 Editorial

UPD 3

Congratulations to the winners.

Div. 1:

1. Petr
2. strapple
3. jiangly
4. tourist
5. Radewoosh

Div. 2 (subject to change):

1. LHNB
2. xoxoKitty
3. EchidnaTea
4. AuroraUwU
5. t1e1

First solves:

Div. 1:
A. 00:02:15 by TKT_YI
B1. 00:08:23 by Petr
B2. 00:14:54 by strapple
C. 00:35:39 by jiangly
D. 00:21:27 by PCTprobability
E. 01:42:55 by XVIII
F. 02:53:16 by olmrgcsi
G. 01:34:40 by rainboy

Div. 2 (subject to change):
A. 00:01:21 by akshW
B. 00:05:49 by khushicodes03
C. 00:10:28 by ansh91627
D1. 00:12:47 by CoderMeow
D2. 00:18:11 by sks4401
E. 00:54:52 by crimson_leaf
F. 00:47:03 by shobhitgagrani.coding33
G. 02:54:37 by dooglius

Привет, Codeforces!

Команда ТГ канала @KogutIvanTutoring рада позвать вас принять участие в первом Div. 3 раунде в этом году — Codeforces Round 1072 (Div. 3) во 12.01.2026 17:35 (Московское время). В этом раунде будет 6-7 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 6-7 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 нашей команды: fstilus, Friendiks, gravitsapa, EzikBro, Boodoochai

Также большое спасибо:

• MikeMirzayanov за системы Polygon и Codeforces.

• Vladosiya за координацию раунда.

• misha.arkhipov, Escapisst, feblokas, lewc, mlovbnee, Yassia, YamOCHca, -_TIMOFEY_-, _liravel_, Gmacem, vintermach, margothequeen, itz_pabloo, sivukhin, Merkurev, the_dragon_emperor, Cyber, MariamH, Arpa, Marckess за тестирование раунда.

Всем удачи!

UPD. Разбор выложен!

Happy new year, Codeforces!

We are glad to invite you to take part in Hello 2026, which will start on Jan/07/2026 17:35 (Moscow time). You will be given 9 problems and 3 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. This round is open and rated for everyone.

Problems are authored by wangmarui, Gold14526, Hoks_, Neil_Qian, Network_Error, jiazhichen844 and xvchongyv.

We would like to thank:

• Um_nik for pre-reviewing the round.
• Proof_by_QED for his wonderful coordination.
• Alexdat2000 for Russian translation.
• Geothermal, StarSilk, and Dominater069 for nutella testing.
• Mindeveloped, ETO_leader, nldr, max0810, A_G, _istil, ian_HLX, nifeshe, paulzrm, sammyuri, catgirl and Intellegent for red testing.
• cuteSubtask, LucaLucaM, cry, Genius_Star_rgw, Friedrich, incra, lkrqwq, LaDeX, pichax, shiny_shine, efishel, Edeeva, Register, AksLolCoding, Watersphere, Lilypad, tzl_Dedicatus545, Caylex and waauto for yellow testing.
• NATO, Cfz_qwq, gotexans, gza, wuhudsm, madlogic and Heartquake for purple testing.
• tybbs, larush, pianapolataa, Terminator-XII, hollis_yang, Nukumizu-Anna, shengxuanyi, chromate00 and cby_ for blue testing.
• wizardMarshall, Solwek, sztcodeforces and lottle1212 for cyan testing.
• yaotianhao0906, lovelyfish and YSY_ for green testing.
• chenzhishuo2012 and Lvl200GoldenDragon for gray testing.
• Lynette_D for unrated testing.
• MikeMirzayanov and KAN for the great Codeforces and Polygon platforms.
• You for participating in this round.

Score Distribution: $$$500 - 1000 - 1500 - (1000 - 2000) - 2250 - 2750 - 4000 - 4000 - (4500 - 1000)$$$

Good Luck & Have Fun!

Update 1: The score distribution have been changed a bit. In particular, problem I will be split into two subtasks.

Update 2: Hacks will be disabled on problems A-D.

Update 3: editorial — https://codeforces.me/blog/entry/149944

Update 4: Congratulations to the winners!

1. maroonrk
2. ecnerwala
3. turmax
4. peti1234
5. kotatsugame
6. hos.lyric
7. BurnedChicken
8. strapple
9. stepanov.aa
10. antontrygubO_o

Hi Codeforces!

2025 comes to an end. However square the year was, we held a number of rounds: 29 Div. 1 and 31 Div. 2-only contests, to be precise! Additionally, 18 Div. 3, 4 Div. 4, and 13 Educational rounds made the schedule even more congested.

December is not only the perfect only time to wrap the year, but also to celebrate and thank all the people who made this year possible. That's why I want to highlight with this post the people whose efforts shaped Codeforces contests.

I'd like to say a huge thank you to every active community member who created and/or prepared problems for Codeforces rounds! Without your ideas and creativity, it would be impossible to hold so fun and interesting competitions. There are so many of you from every corner of the world, so that it's impossible to name everyone here, but one can see the authors of each contest on the contests page. Thank you!

Next, I'd like to extend my deepest gratitude to our coordinators who make sure rounds are the best quality and come on time. Here they are: Error_Yuan, maomao90, FairyWinx, Sugar_fan, satyam343, errorgorn, TheScrasse, 244mhq, Artyom123, Akulyat, Dominater069, flamestorm, abc864197532, cadmiumky, SSerxhs, Kaey, Vladithur, Um_nik, and Proof_by_QED coordinated Div. 1 and Div. 2 rounds this year. These people mostly worked after work of studies and sometimes even through the night to bring the rounds to you. An extra appreciation goes to Um_nik who now pre-reviews all round proposals, making sure the authors receive timely feedback. At the same time, BledDest and his team managed all the Educational rounds, Vladosiya managed all Div. 3 and Div. 4 rounds, with cry and soullless coordinating some of them. Thank you for your amazing work!

And last but not the least, I'd like to thank almost 800 testers who got to know the problems before the time, spotted some mistakes, and gave very useful advice to the problem authors. Again it's not possible to name them all, but huge shout-out to these heroes who tested the most rounds: _istil, chromate00, A_G, N_z__, larush, Error_Yuan, Proof_by_QED, Dominater069, __baozii__, Friedrich, -firefly-, madlogic, Um_nik!

Please join me in applauding all directly and indirectly mentioned people for their exceptional effort! Your work is invaluable for our community. Thank you! With that, I wish you all an exceptional New Year Eve and see you next year!

Hello Codeforces,

As 2025 comes to an end, it is time to start summing up the results.

This post is about the Global Rounds. Since September, we have held a series of three Global Rounds, numbered from 29 to 31.

This is the perfect moment to once again express our gratitude to XTX Markets for their initiative in organizing these rounds and their constant support over the years. Such stability in supporting the competitive programming movement is truly admirable and highly appreciated by the community. I wish XTX Markets a fantastic 2026, full of success and victories!

In each of the three rounds, 50 t-shirts were awarded (to the top 30 participants and 20 random participants ranked between 31st and 500th). This year, we had to change the manufacturing and shipping process, so it is still a work in progress, but things are moving forward, and shipping will begin soon. I would like to take this opportunity to ask the prize winners to respond promptly to any information requests and to meet the deadlines. It is also a good idea to keep your shipping address up to date at https://codeforces.me/settings/delivery.

The results for this series were calculated based on the best two performances out of the three possible rounds. Participants received points depending on their rank (points were awarded to the top 100 participants according to this table). The top 20 participants will receive commemorative hoodies and certificates indicating their rank.

Congratulations to the series winner ecnerwala on a decisive victory! Full results can be found at https://codeforces.me/contests/2147,2164,2180/gp100/best2/standings.

Thank you for participating in the rounds. Would you like another season of Global Rounds in 2026?

Mike

P.S. Here are the top 20 participants. Congratulations on winning a hoodie and a certificate!

Goodbye, 2025. Hello, 2026!

Dear Santa, Please make 2026 a happy year—not just for me, but for everyone. We all need this.

Hello, 2026!

And of course, we have our traditional gifts!

Change Handle Feature

Hurry! Until January 10, you can change your handle (but only once)! Note that next time you will be able to roll back the change or request another handle change only after a year (in December 2026). Choose wisely!

You can change your handle to a new one that hasn't been used by anyone else, or to one that you've previously used. Links to your old profile will automatically redirect to your updated profile.

Again this year, if you've participated in at least 10 rounds, you can request the handle of an inactive participant. This means the participant must have had a period of activity on Codeforces lasting at most 180 days, and this activity must have occurred in 2022 or earlier. The inactive participant must not have posted comments, messages, or similar content, and they must not have participated receiving 'Accepted' in more than 2 contests. In such cases, the handle will be automatically renamed, and the original owner will be notified via email. If the original user requests their handle back, we will roll back the change and restore your previous handle.

If you're unable to change your handle, it means some of the requirements have not been met. Please do not ask me to intervene manually. I especially dislike requests such as, "This is my second account; I took an interesting handle myself." I'm not Santa Claus!

Speaking of handles, I always reminisce about one particular story. Once, a user sent me this message: "Please change my handle from I_love_Valya to I_love_Sveta, as I no longer love Valya..."

New Year's Masquerade of Colors and Ranks

The traditional magical tab has appeared in your profile settings. Happy New Year!