HHSgddgd, Codeforces!!

I am thrilled to invite you to participate in Codeforces Round 1132 (Div. 2), which will take place on Nov/06/2026 17:35 (Moscow time) and probably won't contain a single $$$\text{XOR}$$$ problem. You will be given 6 problems, two of which will be divided into subtasks, and 2 hours and 15 minutes to solve them.

All problems were authored and prepared by ot_dre, d0esn, amof and me.

ALERT ALERT The round may contain interactive and communication problems. We recommend familiarizing yourself with these formats beforehand.

I would also like to express my heartfelt gratitude to everyone who made this round possible:

• nifeshe for making the coordination process so enjoyable and discussing the problems
• Vladosiya for discussing the problems at an early stage
• all our testers:
• all our VIP testers: suprend, ColobocCodeforces, employed, Rvess, __baozii__, temporary1, ne_justlm, linearspace, robert9524, Nyemot, A_G, AksLolCoding, nik_exists, m3tr0, amsraman, Proof_by_QED, Stathis, sammyuri, KWAMP, Pie_TealCompressorDragon, Dragos, flammifer, h4cker3, jeroenodb, samsoom, aryanc403, ItzsleepyXD, catgirl
• MikeMirzayanov and KAN for the Codeforces and Polygon platforms
• You for participating in the round!

The scoring distribution is: $$$(500 + 500) - 1000 - (1000 + 1250) - 2000 - 2500 - 2750$$$.

Hello Codeforces!

We (applepi216 and conqueror_of_tourist) are glad to invite you to Codeforces Round 1133 (Div. 1) and Codeforces Round 1133 (Div. 2), which will start at Nov/07/2026 17:35 (Moscow time).

The contests will run for 2.5 hours and have 6 tasks each. Both contests will be rated.

We want to thank these people, without whom this round would have been impossible:

• 244mhq for the excellent coordination!
• Um_nik for preliminary review of the round.
• users TheOneYouWant and FlakeLCR for proposing problems.
• errorgorn, Adam_GS, AksLolCoding, apgpsoop, YuukiS, dinohaur, ItsNotMeItsYou, misteg168, omsincoconut, oursaco, twosquares, Hori, madlogic, Ritwin, chromate00, Gilwall, conqueror_of_womais for testing and giving a ton of useful feedback!
• MikeMirzayanov and KAN for the wonderful Codeforces and Polygon platforms.

and of course a special thank you to all of you for participating!

The scoring distribution will be released soon.

Hello Codeforces!

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

Educational Codeforces Round 196 (Rated for Div. 2) will start on Nov/04/2026 17:35 (Moscow time).

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 7 problems and 2 hours to solve them. I hope everyone participating finds interesting problems for them to solve.

I would like to express my gratitude to MikeMirzayanov for creating Codeforces and Polygon — without these two platforms, Educational Rounds would be impossible.

Also, big shoutout to the round testers: ashmelev, shnirelman, awoo, FelixArg. Thank you for your feedback!

Our friends at Neapolis University Pafos have message for you:

Computer Science and AI BSc program at Neapolis University Pafos invites high school students to the Youth Coding Challenge on November 29, 2026, the entrance contest for the Competitive Programming track at ACTS 2027.1.

As one of the camp’s organizing partners, we look forward to welcoming you to Paphos, Cyprus, on March 15–25, 2027, for lectures, training contests, and problem discussions with experts including Pavel Mavrin and Niyaz Nigmatullin.

Selection is based on contest results and previous achievements.

Learn more and register by November 27.

See you on the round! Good luck during the contest!

Trick or participate, Codeforces?

We are glad to invite you to our Halloween round, Codeforces Round 1131 (Div. 3), which will start on Oct/31/2026 17:35 (Moscow time).

The problems were authored by wuhudsm, and prepared by wuhudsm and wakanda-forever

You will be given 7 problems and 135 minutes to solve.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks.

Note that the penalty for each wrong submission in this round is 10 minutes. Also, note the rule restricting AI use!!! If you are caught using AI in an unorthodox manner, bad things will happen to you. We will be watching you all...

Remember 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)
• do 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).

I would like to thank:

• cry for coordinating the round;
• __baozii__ for GM testing;
• Edu175, and omsincoconut for M testing;
• Edeeva, WorldWarV, yse, and ReverseFlash081 for CM testing;
• Vladosiya, DivinePunishment, CatsAreCool, Bal_Krishna04, Eikyu,simplelife, expertaq, chromate00, and nik_exists for Expert testing;
• Saidul_1, and linearspace for Specialist testing;
• MikeMirzayanov for the great Codeforces and Polygon platforms;
• And at last but not least, You for participating in the round!

Editorial

Hello, Codeforces!

We start a new season of the Coding Club! This year, things will be different from the last one. Every week, livlivi and I will post a short lecture and a themed contest. Then you will have one week to solve it. If you have any troubles, we will have several teaching assistants, who will help you personally.

The plan for this season is to cover these topics (not sure if we will have enough time, but we will try):

• Core techniques (prefix sums, binary search)
• Dynamic programming
• Graph algorithms (DFS, BFS, MST, shortest paths)
• Data structures (stacks, queues, DSU, segment trees)
• Tree algorithms (DP on tees, LCA)
• String algorithms (tries, KMP, hashing, Aho–Corasick)

The club is starting this week! If you are interested, register here. See you!

Hello, Codeforces!

We are very excited to invite you to participate in Codeforces Round 1130 (Div. 2) which will be held on Oct/26/2026 17:35 (Moscow time). You will be given 2 hours and 15 minutes to solve 7 problems.

The problems were prepared by yvbf, JerrySyr, MoScenix and me.

As yvbf always says, remember to eat well before and after the contest.

We would like to give special thanks to:

• Um_nik for the preliminary review of this contest.
• cry for the brilliant and great coordination.
• AksLolCoding, __baozii__, -firefly- for red testing.
• GUAIKATTO, More, 7_divided_by_3 for yellow testing.
• Edeeva, WorldWarV, yinruiyang for purple testing.
• Misaka16172, nik_exists, Yzm007 for blue testing.
• MORNING for cyan testing.
• MikeMirzayanov, KAN for the great platforms.
• Alexdat2000 for detailed Russian translation.
• TianTianChaoFangDe, tc_adventureking, MaxBlazeIceInk for providing problem ideas ( but declined :-/ ).

UPD1: Score distribution:

We are such a group of committed codeforces users. It's our first time to hold a formal round on codeforces, so we also hope you enjoy the problems!

Good luck and have fun!

UPD2: Congrats to the winners:

Unofficial:

1.peti1234

2.potato167

3.MillionDays

4.Lynkcat

5.maspy

Official:

1.MillionDays

2.RainRecall

3.Hienbeo

4.Koo_Pung-Kei

5.Velz

UPD3: Editorial is open:

Editorial

你好，Codeforces!

We are excited to invite you to participate in Codeforces Round 1129 (Div. 2), which will be held on Oct/24/2026 14:05 (Moscow time). Note the unusual start time of the round.

You will be given 2 hours and 15 minutes to solve 6 problems. One of the problems will be divided into 2 subtasks. At least one problem will be interactive so we recommend reading the guide to interactive problems if you have not encountered them before. All the problems were authored and prepared by Getaway_Car and me, _O_v_O_.

We'd like to express our sincere gratitude to:

• Um_nik for preliminary reviewing the round.
• satyam343 for perfectly coordinating the round.
• RockyYue, JDScript0117, AksLolCoding, lkrqwq, nifeshe, szh131421, harmis_yz, Proof_by_QED, employed, ZQZBD, wangzeyu2013, Eterminal, lrb828281, tkdqmx, RainRecall, esc_qwq, MornStar, Libingyue20111, Dim_Star, liang0504, samsoom, a_foolish_OIer for testing the round and giving helpful feedback.
• zhuchenyao, Danielcdo, __WBJ0429__, ztyroy who didn't test, for being willing to test the round.
• Alexdat2000 for translating this round to Russian.
• MikeMirzayanov and KAN for creating the amazing Codeforces and Polygon platforms.
• You for participating in the round.

Good Luck & Have Fun! We hope you enjoy this round!

UPD1: Scoring distribution:

UPD2: Congratulations to the winners (subject to change):

Official:

1. nike0g
2. TasselFlower
3. binglengmo
4. legendcn
5. lenohoo

Unofficial:

1. peti1234
2. nike0g
3. TasselFlower
4. binglengmo
5. __baozii__

First solves:

A: 00:01:49 by ZeeroBug
B: 00:05:03 by Dipanjali_4184
C: 00:10:14 by wangyizhi
D1: 00:21:41 by TasselFlower
D2: 00:27:57 by TasselFlower
E: 00:41:25 by evenvalue
F: 00:27:55 by jiazhichen844

Editorial

Καλησπέρα/안녕/สวัสดี/أهلا/你好 Codeforces!

With great felicity, immense joviality, and unparalleled positivity, we, a team of authors united by our creativity, originality, ingenuity, and curiosity, consisting of omsincoconut, chromate00, ttamx, yse, Marszpace, an individual of mysterious identity, and me, SpyrosAliv, have the distinct opportunity and absolute pleasure to invite you to WorldQuant Round 1 (Codeforces Round 1128, Div. 1 + Div. 2), an event of exceptional quality and remarkable diversity, which will become a reality on Oct/17/2026 17:35 (Moscow time).

You will be presented with 8 problems of varying complexity, difficulty, and subtlety, with exactly 3 hours of availability to demonstrate your ability, capability, adaptability, versatility, productivity, efficiency, accuracy, agility, rationality, and problem-solving proficiency. Some problems may feature a multiplicity of subtasks, providing additional flexibility and accessibility while preserving the overall integrity of the contest.

Of course, with absolute certainty and without any ambiguity, at least one problem will be a communication problem, introducing an additional layer of interactivity, connectivity, and unpredictability. Therefore, to maximize your probability of success and minimize the possibility of unnecessary challenges, we emphasize the necessity and priority of reading the guide for communication problems before the contest.

Special thanks to the following people for helping make this round a reality:

• flamestorm, simplelife, ItzsleepyXD for proposing problems that are not ultimately used in the round.
• Um_nik for pre-reviewing the problemset;
• Proof_by_QED for being the best coordinator of all time;
• The testers: EvenImage, nifeshe, A_G, __baozii__, Error_Yuan, turska, Stathis, Mentholzzz, cry, Timosh, coder3000, ReverseFlash081, Argentum47, Hori, wakanda-forever, Lxnsr._th, coder3000, cowthecow, Borhom, blackslex,samsoom, nik_exists, Nasa, Mysticmage45, SkyMagic, Teto, coder3000.
• Alexdat2000 for translating statements to Russian;
• MikeMirzayanov and KAN for Polygon and Codeforces platforms.
• and last but not least, You for participating!

Score distribution:

Congratulations to the winners!

1. turmax

2. k1r1t0

3. jiangly

4. tourist

5. strapple

6. idontwannadothisanymore

7. ecnerwala

8. potato167

9. littleju

10. no-girlfriend

Editorial

And now, a few words from the sponsor!

Hello, Codeforces community!

We are happy to welcome you to the WorldQuant Round 1 and proud to support a platform where so many talented programmers learn and compete.

WorldQuant is a global quantitative asset management firm. Founded in 2007, WorldQuant develops and deploys systematic financial strategies across a broad range of asset classes and global markets. Our teams work collaboratively to drive the production of high-quality predictive signals (alphas) and financial strategies — the foundation of a balanced, global investment platform.

At WorldQuant Armenia, talented people with diverse backgrounds, including participants and prize winners of competitions like IMC, IMO, ICPC, and IPhO, work together to tackle challenging problems. We value curiosity, teamwork, and the passion to learn, creating an environment where people can grow, share ideas, and achieve great things together.

We are looking for talented individuals to join our team at WorldQuant Armenia in the following roles:

• Quantitative Researcher
• Senior Python Engineer
• AI Software Developer

Please note that relocation to Armenia is required, and WorldQuant can provide assistance with relocation for successful candidates.

To apply, fill in the application form.

The winners will receive our exclusive branded swag:

• Hoodies + T-shirts for the top 5
• T-shirts for participants ranked 6–30

Whether you are competing for the top places or simply challenging yourself to improve, we hope you have a great time!

PS We reserve the right to apply strict compliance checks when finalizing the results in order to prevent unfair participation and rule violations.

Please note that prize delivery to certain countries, states, provinces, or territories may be subject to applicable sanctions, trade restrictions, or other legal requirements. We will make every reasonable effort to deliver prizes to all eligible winners, subject to any restrictions that may apply.