Hola Codeforces!

We are really excited to invite you to participate in Codeforces Round #1093 (Div. 1) and Codeforces Round #1093 (Div. 2), which will be held on Apr/13/2026 17:35 (Moscow time).

For division 1, you will be given 2 hours to solve 5 problems, for division 2, you will be given 2 hours to solve 6 problems. Note that at least one of the problems will be divided into subtasks. Furthermore, at least one problem may be interactive, so please read the guide for interactive problems if you are not familiar with them.

The scoring distribution will be announced later.

The problems were authored and prepared by misteg168, danx, rlidon2006, and Misuki.

We would really like to thank the following people for making this round possible:

244mhq for his orz coordination and support throughout the round, and also for the Russian translation.

A_G, dinohaur, zltzlt, omeganot, IceKnight1093, fishy15, ub33, awang11, Justinshao, Pablo-No, FelixMP, madlogic, pandaa73, chromate00, IceSerpent, Lucia_Aparicio, aniervs, and Kalufas for testing the round and providing priceless feedback.

MikeMirzayanov and KAN for the great platforms Codeforces and Polygon.

And finally, You, for participating!

We wish you all an exciting experience. Good luck and have fun!

UPD1 Scoring distribution:

div2 500-1000-1500-(1000+1000)+2500+3000

div1 500-(750+500)-1750-2250-3000

UPD2 Spain's Olympiad in Informatics:

This round was based on the Spanish Olympiad in Informatics, which took place last weekend. Thanks to all contributors!

UPD3 Editorial is out

Note the unusual time of the round.

Hello, Codeforces!

Tsinghua University’s Student Association of Algorithmic Competitions (THUSAAC) is pleased to invite you to participate in Codeforces Round 1092 (Unrated, Div. 1, Based on THUPC 2026 — Finals) and Codeforces Round 1092 (Unrated, Div. 2, Based on THUPC 2026 — Finals) on Apr/12/2026 08:35 (Moscow time). This round will be UNRATED for everyone. You will be given 3 hours to solve 7 problems for Division 1 and 6 problems for Division 2.

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

What’s more, it’s the first time that we will provide a local testing tool to help the contestants test their solutions on interactive problems. To get familiar with the testing tool, you may download the sample testing tool for an earlier interactive problem and an earlier run-twice problem. You can download them from the materials of the above problems.

Our team of amazing problem setters include: Warriors_Cat, E.Space, Ecrade_, SpiritualKhorosho, dapingguo8, xiaoziyao, Kratrissa, crazy_sea, zhouhuanyi, Doqe. Some of the problems prepared were not used in the final contest but we would still like to thank them nonetheless.

We would also like to express our gratitude to the following individuals:

• KAN for helping to host the round;

• Error_Yuan for coordination and helping with the problem preparation;

• Alexdat2000 for translating the problems into Russian;

• The team of problem setters for crosschecking the problems and also donghanwen, Iam1789, Zesty_Fox, sszcdjr, YuukiS, A_G, nifeshe, Caylex, a_little_cute, simplelife, Serval, wmrqwq for testing the contest and providing us very useful feedback;

• Tsinghua University’s administration, especially our advisor Wentao Han for helping us in all means possible to ensure the smooth organisation of the whole THUPC event;

• MikeMirzayanov for the amazing Codeforces and Polygon platform!

THUPC is an annual event hosted by Tsinghua University’s Student Association of Algorithmic Competitions (THUSAAC). It is the largest student-run competitive programming contest in China with the top 100 Competitive Programming teams from all over China coming onsite to vie for the crown of BEST CP Team in China after qualifying from a pool of 1000+ teams.

Moreover, this year is the 10-th anniversary of THUPC. Years of a decade have distilled countless brilliant and sparkling moments, and our gathering today is no less memorable. Our sincere gratitude goes to all staff and volunteers of THUSAAC. None of these glory would have been possible to be realized without your efforts!

By experiencing a series of collisions between intellect and joy, we hope you will enjoy and have fun in the contest. Good luck!

The scoring distribution:

Div. 2: $$$500 -1000-1750-2250-2750-4000$$$

Div. 1: $$$750-1250-1750-2750-3000-4000-5000$$$

UPD: Due to technical reasons, this round will be UNRATED. We are really sorry for any inconvenience caused by this :(

UPD2: Reasons of being unrated: The official contest started 3.5 hours earlier than the codeforces round. The problem statements unexpectedly leaked from the public scoreboard shortly after the official contest begins, and it spread a bit widely before the codeforces round begins, so the round can't be made rated now... We apologize for our mistakes :(

UPD3: Editorial

Is happening on April 11th at 1 PM UTC here on Codeforces. The qual lasts 4 hours.

MCC is a new generation programming contest, with a 24 hour onsite final, broad variety of problems (algorithmic challenges, optimization puzzles, plus some weird problems). You can participate in a team of 3 or less, the use of AI is allowed and encouraged.

You can still register, but please do it by the end of the day April 10th to get you log in info in time. Register here: https://midnightcodecup.org/

If you already registered

You'll get an email from Codeforces with your login information on April 10th.

Log in with those credentials and wait for the problem statements to become available at 1PM UTC on Saturday!

Important: If you registered through CF yesterday — this was a registration page that was open by mistake, please register via the official website: https://midnightcodecup.org/

Who qualifies for the finals?

Top 25 teams from the qual, plus 5 wildcards we'll select by the end of April.

That's it — see you soon!

P.S. Subscribe to our X/Insta for updates

P.P.S Last year's qual problems can be found here: https://mirror.codeforces.com/blog/entry/141787

Hello Codeforces!

We're glad to invite everyone to participate in Codeforces Round #1091 and CodeCraft '26 (Div. 2) — IIIT Programming Club's eighth round on CF! The contest will start on Apr/07/2026 17:35 (Moscow time) and will be rated for all participants with a rating below 2100.

There are 8 problems to solve in 2 hour and 15 minutes, with two of these being easy and hard versions. You'd want to read all the problems :)

This round has been over a year in the making, and a lot of people helped us put it together. Thank you to:

• cry and Error_Yuan for their wonderful coordination.
• Um_nik and satyam343 for a detailed review of our initial set and bumping the quality.
• Alexdat2000 for Russian translations.
• authors h2rsh, SilverTongue1729, Faizal, tanaygad, SavageFighter001, Prakul_Agrawal, penguinnoob, AS23, sumit_kk10, kevaljain, shakr, and biswas for cute problems and prep.
• ppt1524, Manav_Shah24, and _anushka__ who helped with brainstorming and preparing problem ideas.
• Dominater069, _istil, __baozii__, nifeshe, awesomeguy856, Igen, akcube, AksLolCoding, weirdflexbutok, MattTheNub, Friedrich, efishel, d1mk, SpyrosAliv, CutSandstone, Argentum47, simplelife, chromate00, DivinePunishment, shreyas333, and nik_exists for testing the round.
• MikeMirzayanov and KAN for Codeforces and Polygon.

Hope you enjoy the contest!

Score distribution: $$$500 - 1000 - 1500 - 1500 - 2000 - 2750 - 3250 - 3750$$$

UPD: The editorial has been published.

UPD: Congratulations to the winners!

Top 5

• ksun48
• maspy
• A_G
• Timmy1003
• Musa_82FaGm

Among Rated Participants

• Timmy1003
• Musa_82FaGm
• rep
• woyebuzhidaowoshishui
• Shakhzod_Toshpulatov

We hope you had fun! Here's the team after 2h of watching submissions roll in. Yes, the shirts still say '23. Priorities.

Hello Codeforces!!

I (macaquedev) and damamila would like to invite all of you to my long-awaited Codeforces Round 1090 (Div. 4) on Apr/04/2026 17:35 (Moscow time)! You will be given $$$6$$$ or $$$7$$$ problems, and you will be given $$$2$$$ hours and $$$15$$$ minutes to solve them. We hope that you will find the problems interesting, and that all participants will learn at least $$$6$$$, $$$7$$$ or (ideally) $$$67$$$ things.

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 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 official participants.

Only trusted participants of the fourth division will be included in the official standings table. This is a forced measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:

• take part in at least five rated rounds (and solve at least one problem in each of them),
• do not have a point of 1400 or higher in the rating.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), you may choose to participate rated or unrated.

Large text, to get your attention for the following:

PLEASE NOTE the rule restricting AI use. If you are caught using AI in an unorthodox manner, either by us manually or detected automatically, YOUR ACCOUNT WILL BE TERMINATED. I will be actively scouring submissions and terminating rulebreakers. Remember that the author of this round is also the creator and guardian of cry's basement, also known as the Cheater Database.

Anyway, I would like to say a massive "thank you" to all the following people for making this round possible:

• cry, for coordinating the round and not rejecting every single problem idea I've invented (although it came quite close).
• reirugan and Proof_by_QED for reading through my 3am ramblings, where I invented increasingly more contrived problems and presented completely fake GPT "solutions" with complete confidence.
• damamila for contributing a problem.
• Vladosiya for Russian translations.
• Our testers: temporary1, Edeeva, __baozii__, yud08, -firefly-, omsincoconut, efishel, Intellegent, Argentum47, AG-88301, wuhudsm, wakanda-forever, CatalanConvolution, yse, p0tato, vladimirfilip, simplelife, sammyuri, RedMinecrafter101, Friedrich, tin.le2, damamila, SpyrosAliv, AksLolCoding, chromate00, pop, Demarkok.
• Dominater069, for testing 20 hours before the contest and offering absolutely no useful feedback.
• Our cheater tester, Jasonwei08, who got banned from the site between when he tested and when he got caught.
• tenaciousOtter, for being a great friend and keeping me somewhat sane. (And, of course, all my amazing friends who aren't on this site).
• MikeMirzayanov, for creating this site, which, despite its many issues, has been a constant in my life for far too long and I have grown to love parts of.
• You, for participating and not cheating.

Update: Editorial is here.

Hello, Codefoolers!

We, AlperenT, Ari, ToxicPie9, flamestorm, prvocislo, temporary1, and willy108 would like to invite everyone on Codeforces to April Fools Day Contest 2026! The 14th April Fools Day Contest will take place on Apr/01/2026 17:35 (Moscow time). 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 $$$n$$$ problems where $$$n$$$ is the number of different AI models I used today 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.

There will be at least one non-interactive problem. In case you do not care about those problems, here is the guide for interactive problems.

Please note that the round is unrated and that the penalty for a wrong submission is 10 minutes. Furthermore, similar to other contests, it is not allowed to use AI help unless permitted in this blog.

To get an idea of what the contest will look like, you can check out the contests of the past years: 2012, 2013, 2014, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026. (Does anyone ever click these anyway, why do I have to keep adding them each year?)

Thanks to our precious testers:

ChatGPT, Gemini, Claude, Grok, DeepSeek, and a few others who preferred to remain anonymous.

It is, without a doubt, the least enjoyable part of April Fools for us to respond to clarification requests with funny responses. It is certainly not the main motivator for us to prepare these contests in the first place. Therefore, please refrain from continuing this tradition.

Good luck, and have fun!

Update 1:

Editorial is released!

Update 2:

Congratulations to the winners:

1. ksun48
2. SeptaCube
3. pwild
4. 0x0c5cbae8
5. ishmeal

And the first solves on each problem (after blatant cheaters):

• A: shash4321 — 0 minutes
• B: ksun48 — 0 minutes
• C: jdurie — 4 minutes
• D: thespace — 3 minutes
• E: ksun48 — 4 minutes
• F: SeptaCube — 13 minutes
• G: bronze_coder — 51 minutes
• H: circle977 — 1 minutes
• I: Egg_Knight — 33 minutes
• J: Nagerhide — 11 minutes

Hello Codeforces!

We are really excited to invite you to participate in Codeforces Round 1089 (Div. 2), which will be held on Mar/29/2026 17:35 (Moscow time).

You will be given $$$6$$$ "simple" problems and $$$2$$$ hour $$$15$$$ minutes to solve them. Note that one of the problems will be further divided into $$$2$$$ subtasks. Furthermore, some of the problems may be interactive, so please read the guide for interactive problems if you are not familiar with them. This round will be rated for the participants with rating lower than 2100.

The scoring distribution is as follows:

The problems are authored and prepared by simplelife, ritam1234, __baozii__, and me.

We would really like to thank the following people for making this round possible:

• cry for his orz coordination and support throughout the round, and also for rejecting a lot of problems.
• Alexdat2000 for Russian translation.
• __baozii__, wuhudsm and Intellegent for VVIP testing.
• VladiG, sammyuri and macaquedev for their "Special Contribution".
• Dominater069 for LGM testing
• kevinxiehk, awesomeguy856, sammyuri, _istil for Red testing.
• amsraman, awang11, Proof_by_QED, temporary1, VladiG, CutSandstone, -firefly-, AksLolCoding, Friedrich and 0x3F for Orange testing.
• SpyrosAliv, AkShukla, tin.le2, wakanda-forever and Edeeva for Purple testing.
• IceSerpent, DivinePunishment, chromate00, Ermiooo159, expertaq, Ananya_agr, alex_rider123, kryoton_98, susvent, Jteh, apollo07 and beaten_by_ai for Blue testing.
• nik_exists, dipamsen, GlidingNinja_ccn and RJ_Parin_fr for Cyan testing.
• ukcsstudent for Green testing.
• MikeMirzayanov and KAN for the Codeforces and Polygon platforms.
• And finally, You, for participating.

UPD : Editorial link. Hope you enjoyed the round. We are sorry for the unexpectedly hard C2.

UDP2 : Congratulations to the winners!

Top $$$5$$$ overall: (subject to change)

1. Geothermal
2. YuukiS
3. NotNanYan
4. yanchengzhi
5. im_xRayVN

Top $$$5$$$ rated participants: (subject to change)

1. NotNanYan
2. yanchengzhi
3. im_xRayVN
4. NekoType_
5. makeit427

Hello Codeforces

After countless nights of yapping, bedfight duels, and failed zero cycles

The authors of the three best Div. 1 of all time, nifeshe, chromate00, and I, have joined forces to create the Division $$$1+2$$$ round that will break the internet: Nebius Round 2 (Codeforces Round 1088, Div. 1 + Div. 2), which will be held on Mar/28/2026 17:45 (Moscow time). This round will be combined for Division $$$1$$$ and Division $$$2$$$ and will be rated for everyone.

You will have $$$2.5$$$ hours to solve $$$8$$$ problems. Between $$$6$$$ and $$$7$$$ problems will not be split into subtasks. Also, between $$$6$$$ and $$$7$$$ problems will not be interactive, so you are recommended to read the guide to interactive problems if you have not encountered them before.

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

• Um_nik for pre-reviewing the round.
• cadmiumky for the coordination and helping with preparation.
• BurnedChicken for VIP testing.
• Dominater069, Geothermal, EvenImage, and SomethingNew for LGM testing.
• sammyuri, __baozii__, dinohaur, Dragos, rolandpetrean, Sana, and _istil, for red testing.
• Lilypad, JeffreyLC, misteg168, AksLolCoding, mwen, and PMiguelez for orange testing.
• efishel, tvladm, and madlogic for purple testing.
• mathtsai, Jamshed11, lev1106, Argentum47, simplelife, and SpyrosAliv for blue testing.
• nik_exists for cyan testing.
• Alexdat2000 for translating statements to Russian.
• MikeMirzayanov for Codeforces and Polygon.
• and last but not least, You for participating!

The scoring distribution is below.

Now, a few words from our sponsor Nebius!

We are a Nasdaq-listed company building cloud infrastructure and hyperscale platforms for AI innovators worldwide. We support the entire AI lifecycle from training to deployment, powered by high-performance NVIDIA GPUs. Behind the platform is a global team of over 1400 people, including more than 400 engineers working at the frontier of AI, supported by a dedicated in-house AI R&D team.

We’re thrilled to invite you to enroll into our first Early Talent Program! It’s designed for students and new grads to learn, contribute to building AI infrastructure, and grow into core members of our team.

If you are interested, please fill in this form. It could be your opportunity to start your career journey at Nebius.

And last but not least about the prizes for Nebius Round 2.

We’ve got something exciting lined up for the top 15 contestants on the leaderboard. Rewards come in the form of credits for Nebius Token Factory – they can be spent on inferring AI models, eg. generating text or powering AI-driven applications or agents.

• 🥇 1st place – equivalent of $1000
• 🥈 2nd & 🥉 3rd places — $500 each
• 🥇 4th–15th places — $100 each

We hope you will participate and enjoy the problems. Good luck!

UPD: the contest has been delayed by 10 minutes to allow everyone to register.

UPD2: https://mirror.codeforces.com/blog/entry/152448 editorial

Top 15:

1. turmax
2. tourist
3. ksun48
4. StarSilk
5. littleju
6. hos.lyric
7. literalchild
8. pigstd
9. Golovanov399
10. jeroenodb
11. Ormlis
12. ecnerwala
13. potato167
14. Kevin114514
15. Maksim1744

Hello, Codeforces! 👋

We’re Nebius.

You might remember our Welcome Round a few years ago, and we're back with another round! We invite you to take part in our Second round on Codeforces: Nebius Round 2 (Codeforces Round 1088, Div. 1 + Div. 2). Join us on Mar/28/2026 17:45 (Moscow time) and test your skills by solving problems!

In the meantime, we want to share something big.

We’re launching our first Early Talent Program for students and recent grads.

Quick intro. I used to coordinate Codeforces rounds back in 2014–2015, did IOI/ICPC, and was pretty active here in the 2010s. Now I’m a Director of Engineering at Nebius, working on our new agentic search direction. As a former intern of similar program, I’d be really happy to see more CF folks join us.

This is not a “watch and learn” internship. You’ll be working on real systems such as AI infrastructure, cloud, product, and AI RnD, shipping things, and having actual ownership.

What you get

Details

Roles and locations:

• AI Researcher — Amsterdam (HQ), Berlin, Remote (from Europe & United States)
• Backend Developer — Amsterdam (HQ)
• Full Stack Developer — Amsterdam (HQ)
• ML Engineer — Life Sciences — Amsterdam (HQ)
• AI/ML Specialist Solution Architect — Remote (from United States)
• Network Engineer — Amsterdam (HQ)
• Site Reliability Engineer — Amsterdam (HQ)
• Cloud Engineer — Amsterdam (HQ)
• Data Center Technician — Finland, United States, Paris, Tel Aviv

Who we’re looking for

• Students / recent grads / early specialists
• Strong fundamentals + interest in large-scale systems
• Candidates eligible to work full-time on-site in the role’s location

Use the link below to complete the application form for the open positions.

Till soon!

Hello, Codeforces!

__baozii__ and I are glad to invite you to participate in Codeforces Round 1087 (Div. 2). The round will take place at Mar/21/2026 17:35 (Moscow time). There will be $$$6$$$ problems, and you will have $$$2$$$ hours to solve them. The round will be held according to the Codeforces rules and will be rated for division $$$2$$$.

At least one problem will be interactive, so we highly recommend you to read guide for interactive problems before the contest.

UPD: score distribution:$$$500 - 750 - 1500 - 1750 - 2250 - 3000$$$.
UPD:editorial

We would like to thank:

• Sugar_fan for coordination.
• Alexdat2000 for Russian translation.
• MikeMirzayanov and KAN for the best platform.
• Um_nik, Dominater069 for nutella testing.
• Tobo, Intellegent, A_G, k1r1t0, _istil, nifeshe for red testing.
• 0x3F, Proof_by_QED, FelixArg, DNR, -firefly-, Timosh, Arpa for orange testing.
• madlogic, Amao_Fox, Jamshed11 for purple testing.
• chromate00, simplelife, Argentum47, satyam343, SkyWave2022 for blue testing.

Wishing everyone good luck and high ratings!

upd:

top $$$10$$$:

1. bismispis
2. 415411
3. TripleM5da
4. StarSilk
5. undefined_Ryan
6. maspy
7. Cody473
8. antontrygubO_o
9. YuukiS
10. potato167

top $$$10$$$ rated:

1. bismispis
2. undefined_Ryan
3. Cody473
4. qwertyuiojhygtfdfg
5. AJ123496
6. pixelcoder20
7. Ravnik
8. Khai2007
9. ixumqwq
10. _annhien_ruby22

Notes that there will be an update about the top $$$10$$$ after roll-back.