Hello Codeforces!

The series of Educational Rounds continues thanks to the support of the Neapolis University Pafos.

On Nov/28/2025 17:35 (Moscow time) Educational Codeforces Round 185 (Rated for Div. 2) will start.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Adilbek adedalic Dalabaev, Ivan BledDest Androsov, Maksim Neon Mescheryakov, Roman Roms Glazov, Maksim FelixArg Novotochinov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

UPD: Editorial is out

Ciao, Codeforces! We're glad to invite you to take part in Codeforces Round 1066 (Div. 1 + Div. 2), which will start on Nov/23/2025 12:35 (Moscow time). You will be given 9 problems and 3 hours to solve them in both divisions. The round will share some problems with The 2025 ICPC Southwestern Europe Regional Contest (SWERC) 2025.

Note the unusual starting time.

Some of the problems might be interactive, so please read the guide for interactive problems if you are not familiar with it.

The problems were authored and prepared by KLPP and me.

We would like to thank

• Dominater069 for his 💭 💡 🎈 coordination;
• Alexdat2000 for Russian translation;
• dario2994 for VIP testing;
• Geothermal, MrBrionix, xiaowuc1, SmolBrain, awoo, Intellegent, IceKnight1093, MridulAhi, Adam_GS, A_G, Sana, Virv, ha___il, chromate00, beaten_by_ai for testing;
• {Rafi22, surgutti, Krzychuo}, {Akulyat, arzhantsev64, okwedook}, {AlperenT, izhang, Extile} for team testing;
• the SWERC judges team for judging the problems;
• MikeMirzayanov for creating Codeforces and Polygon;
• dario2994 for creating pol2dom, a tool to convert problems from the Polygon format to the SWERC format with minimal effort.

The score distribution will be announced after the onsite contest starts.

We hope you'll like the problemset!

UPD 1: The score distribution is as follows:

$$$500 + 1000 + 1500 + 1500 + 2000 + 2500 + 3000 + 3750 + 4000$$$

UPD 2: Upsolving & viewing of solutions and tests will be closed until the end of the onsite contest (13:30 UTC, 1 hour after the Codeforces round ends). Please also refrain from discussing the problems in public until that time.

UPD 3: Congratulations to the winners:

• Rank $$$1$$$ : tourist
• Rank $$$2$$$ : jiangbowen
• Rank $$$3$$$ : ksun48
• Rank $$$4$$$ : PEIMUDA
• Rank $$$5$$$ : Radewoosh (Only solve on problem I!)
• Rank $$$6$$$ : VivaciousAubergine
• Rank $$$7$$$ : qiuzx
• Rank $$$8$$$ : Rinne_qwq
• Rank $$$9$$$ : Rubikun
• Rank $$$10$$$ : maspy

UPD 4: The editorial is out.

Hello, Codeforces!

I am very excited to invite you to my second-ever contest, Codeforces Round 1065 (Div. 3), which will start on Nov/20/2025 17:35 (Moscow time)! In this contest, you will be given 2 hours and 30 minutes to solve 7 problems, two of which have been split into subtasks. The subtasks for a given problem are not necessarily placed adjacently in the problemset.

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).

Also, note the rule restricting the use of AI. If you are caught breaking this rule, you will be condemned to life spent in prison the basement of some unspecified Codeforces user. Said person's basement is a rather unenjoyable place to live in, so I would advise adhering to the rules.

I would like to thank the following people for helping make this round possible!

• cry for his excellent coordination;
• Vladosiya for translating the statements into Russian;
• satyam343 and Lilypad for discussing problem ideas with me;
• djm03178, satyam343, Dominater069, and Intellegent for being very important people who have contributed significantly to the round;
• Dominater069, nifeshe, Intellegent, catgirl, temporary1, Friedrich, djm03178, wuhudsm, -firefly-, efishel, Edeeva, yse, SpyrosAliv, ritam1234, chromate00, Ermiooo159, kevlu8, Argentum47, expertaq, simplelife, ByteRaider, and RJ_Parin_fr for testing;
• macaquedev for pretending to test;
• MikeMirzayanov for the incredible Codeforces and Polygon platforms;
• and most importantly of all, You for participating!

Good luck, and have fun!

UPDATE: Due to issues with Cloudflare, the round has been rescheduled for Nov/20/2025 17:35 (Moscow time).

UPDATE: Editorial

Hello, Codeforces! We're glad to invite you to take part in Codeforces Round 1064 (Div. 1) and Codeforces Round 1064 (Div. 2), which will start on Nov/16/2025 17:35 (Moscow time). You will be given 6 problems and 2 hours to solve them in both divisions.

The problems were authored and prepared by le0n and me.

We would like to thank:

• Sugar_fan for his coordination;
• Alexdat2000 for Russian translation;
• liqingyang, ZhouYuHang for providing problems that were ultimately not used;
• Tobo, _istil, zhoukangyang, wenhao801, baka24, zhaohaikun, xcyle, _RedWine_, Bossusuprem, mzen, phir., dXqwq, songhongyi, SubgraphCounting, Seg_Tree_, Brooksx, A2_Chaos, jhgfds, Crystally, Um_nik, Friedrich, qbf, sunzihang, EvenImage, Arpa, Adam_GS for testing;
• TheScrasse, Error_Yuan and others who were invited but unable to test for reasons;
• MikeMirzayanov for creating Codeforces and Polygon.

Score distribution:

• Div. 1: $$$500-1000-1500-2500-3000-4000$$$
• Div. 2: $$$500-750-1000-1500-2000-3000$$$

We hope you'll enjoy the problems!

UPD: Congratulations to top $$$5$$$ in Div. 1 and Div. 2.

Div. 1:

1. maroonrk, achieving perfect score at an astonishing 01:18:30!
2. JDScript0117, with an outstanding comeback at 01:55:46!
3. Benq
4. ksun48
5. Nachia

Div. 2:

1. __lucailie, with a final solve at 01:59:15!
2. weertyu
3. su_da
4. Axiom_
5. WangYuanyi

First solves:

Div. 1:

A: ksun48
B: Benq
C: OrangeEye
D: Benq
E: Benq
F: maroonrk

Div. 2:

A: f___off
B: Animesh--__--
C: lemmec0de
D: Doraemon-_-
E: Shakhzod_Toshpulatov
F: kyUUKoU

UPD: Editorial is out!

Hello Codeforces!

I am pleased to invite you to participate in 2025 ICPC Asia Taichung Regional Contest (Unrated, Online Mirror, ICPC Rules, Preferably Teams), which will be held on Nov/16/2025 04:50 (Moscow time). This is an online mirror contest for the 2025 ICPC Asia Taichung Regional Contest. 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.

We have an excellent judge team (Regional Contest Director Ling-Ju Hung, Chief Judge Peter Rossmanith, baluteshih, henotrix, ToxicPie9, marmot0814, kasuistry, cthbst, leo900807, olmrgcsi, hank55663, alan8585, waynetuinfor, CindyLinz, samsam2310, ltf0501, LFsWang, Jeffrey, tmt514), outstanding task authors not from the judges (for both the preliminary contest and the regional: Jinn-Shyong Yang, Shik, smallbird, Shenghui Chen, Kuroni), and strong tester teams (nikilrselvam, Vince729, applepi216, qq11123334, LiuYun40066, SorahISA, -1e11, rgnerdplayer, 2qbingxuan) this year! The judges greatly appreciate the testers for their valuable feedback!

Last but not least, we would like to give a big shout-out and express our gratitude to MikeMirzayanov for creating the incredible Codeforces platform, and to Mike and Vladosiya for all their support in making this online mirror contest possible!

On behalf of the 2025 ICPC Asia Taichung Regional Contest Judge Team (with Regional Contest Director Ling-Ju Hung, Chief Judge Peter Rossmanith), we hope you enjoy this contest and have fun!

Of course, this contest will be unrated.

For more information about the regional contest, please see the contest website. There will also be live streams!

UPDATE: The contest will be postponed for 15 minutes as the contestants are still entering the contest hall. We are very sorry for the delay.

UPDATE2: The full list of the judge teams, task authors, and the tester teams are up! We will upload solution hints in the next few days, please stay tuned :)

UPDATE3: We have a YouTube playlist covering solutions to most problems. Solution hint documents will be updated soon.

Hello Codeforces!

The series of Educational Rounds continues thanks to the support of the Neapolis University Pafos.

On Nov/14/2025 17:35 (Moscow time) Educational Codeforces Round 184 (Rated for Div. 2) will start.

This round will be rated for the participants with rating lower than 2100. It will be held on extended ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest, you will have 12 hours to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Adilbek adedalic Dalabaev, Ivan BledDest Androsov, Maksim Neon Mescheryakov, Roman Roms Glazov, Maksim FelixArg Novotochinov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

UPD: Editorial is out

ICPC Challenge Championship 2025 hosted and powered by Huawei has just started! It's a 5-hour onsite competition in Shanghai at the new Huawei LianQiu Lake Campus with a monetary prizes for the winners! Who will you be rooting for?

Contestants:

Player-coaches:

Καλησπέρα, Codeforces!

I am very excited to invite you to participate in Codeforces Round 1063 (Div. 2), which will take place on Nov/10/2025 18:05 (Moscow time). Please note the unusual starting time (30 minutes after the standard starting time).

You will be given 5 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. This round will be rated for all participants with rating below 2100. The problems were authored by me, and prepared by Proof_by_QED and me. We are also excited to announce that:

This will be the first rated round to feature a communication problem.

Make sure that you are familiar with the problem format of communication problems. Recently, Testing Round 20 (Unrated, Communication Problems) was held in order to introduce this new type of problems. Please read the blog on communcation problems and familiarize yourself with these problems. Note that it is the first time we are experimenting with communication problems in a rated round, so please keep this in mind if you choose to participate.

Additional Note: In this round, hacks will be disabled on problems A,B,C and we will have pretests=systests. Hacks will be enabled on D,E as usual.

This round would not be possible without the help of the following people:

• Proof_by_QED for his very good (and first) coordination, and satyam343 for helping us both make this round better;
• Alexdat2000 for russian statement translation;
• The testers: Dominater069, A_G, Andreasyan, __baozii__, rui_er, _istil, nifeshe, Intellegent, fishy15, efishel, wuhudsm, AksLolCoding, FetFot, mzen, temporary1, turska, Timosh, cry, rangerscowboys, -firefly-, Friedrich, madlogic, pupilemus, sokratisi, pop, Lilypad, Edeeva, cowthecow, coder3000, macaquedev, Teto, chromate00, Non-origination, Stathis, pianapolataa, radaiosm7, beaten_by_ai, Vladosiya, Banis, AG-88301, Godgift42, streidi, ALnQ417, Ashrayy;
• MikeMirzayanov and KAN for Polygon and Codeforces platforms.

Score distribution: $$$500 - 1000 - 1250 - (1500 - 1250) - 2750$$$.

Editorial

Winners:

Div.1+2:

• jiangly
• maspy
• ksun48
• allvik66
• potato167

Div.2:

• KimikoLiliana
• duong3982
• Alex239
• chimbunhatvn
• Hello_zoka

Hello, Codeforces!

We are pleased to announce the resumption of the Global Rounds. Thanks to XTX Markets for supporting the initiative! In 2025, we will hold 3 such rounds. The series results will take into account the best 2 participations out of 3.

On Nov/06/2025 17:35 (Moscow time) we will host Codeforces Global Round 30 (Div. 1 + Div. 2).

Codeforces Global Round 30 marks the second 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 8 problems were authored and prepared by our 8 authors: 244mhq, cmk666, Daniel777, JoesSR, Link_Cut_qwq, NetSpeed1, zjy2008 and me. There is at least one interactive problem, so I strongly urge you to read the guide if you are unfamiliar with the format.

We would also like to thank:

• 244mhq for his excellent coordination.
• Daniel081024, gyydp123_LIM, Little09, operator_, Zhouershan for discussing the tasks with us.
• Dominater069 and Um_nik for

  LGM

  testing.
• GroupMatrix, fake_banana, Imdie, zltzlt, _l_l_, _istil, hxhhxh, Daniel081024, nifeshe and omeganot for

  IGM

  and

  GM

  testing.
• awoo and qiuyuanzhi for

  IM

  and

  M

  testing.
• madlogic, hepp, Hori and Comentropy for

  CM

  testing.
• chromate00, Non-origination and larush for

  Expert

  testing.
• dazlersan1 for

  Specialist

  testing.
• _Jasonshan10_ and decimal10 for Unrated testing.
• 244mhq for translating the statements to Russian.
• MikeMirzayanov for creating the Codeforces and Polygon platform.
• And at last but not least,

  You

  for participating in the round!

Round Information:

• Duration: 180 minutes.
• Number of problems: 8 problems with 1 subtask.
• Score distribution: 500 + 750 + 1500 + 1750 + 2250 + (2500 + 1500) + 3500 + 5500

GL & HF!

UPD:

Congrats to the winners!

1. Otomachi_Una
2. Kevin114514
3. dXqwq
4. ksun48
5. VivaciousAubergine
6. qiuzx
7. strapple
8. hos.lyric
9. Radewoosh
10. StarSilk
11. tourist
12. maroonrk
13. potato167
14. Nachia
15. BurnedChicken

First Solves:

A: Away_in_the_heavens
B: ksun48
C: Depressed_sad_boy
D: ksun48
E: Kevin114514
F1: Otomachi_Una
F2: Otomachi_Una
G: qiuzx
H: rainboy

UPD2.

Editorial