By majk, 19 hours ago, In English,


Are you tired after a weekend of three (3) contests? Or are you ready for another one? On Dec/17/2019 18:05 (Moscow time) we will host Codeforces Global Round 6!

It is the sixth round of a new series of Codeforces Global Rounds supported by XTX Markets. The rounds are open for everybody, the rating will be updated for everybody.

You will be given 8 problems and 150 minutes to solve them. The scoring distribution will be provided later, but prior to the contest start.

The prizes for this round:

  • 30 best participants get a t-shirt.
  • 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.

The prizes for the 6-round series in 2019 (current results):

  • In each round top-100 participants get points according to the table.
  • The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
  • The best 20 participants over the whole series get sweatshirts and place certificates.

The problems of this round were developed by me. I will be available on Discord to discuss the problems after the contest.

I would like to thank:

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By BledDest, history, 44 hours ago, translation, In English,

Hello Codeforces!

Codeforces Round #608 (Div. 2) will be held on Dec/15/2019 12:05 (Moscow time). The round will be rated for Div. 2 contestants. There will be 6 problems for 2 hours. Please, notice that the start time is unusual.

The round will be rated for the participants with rating lower than 2100. The statements will be available in Russian and English.

The round coincides with (and is based on) a local Saratov's olympiad for high school students. That's why we ask the participants of the olympiad to stay silent and don't share the statements of the contest with anyone. Unfortunately, we cannot add all the problems to the round, it will contain only six problems.

The problems were proposed and prepared by Alexander fcspartakm Frolov, Adilbek adedalic Dalabaev, Vladimir Vovuh Petrov and me.

We also would like to express our gratitude to Mike MikeMirzayanov Mirzayanov for the permission to make a mirror and Codeforces and Polygon platforms, to our coordinator Dmitry _kun_ Sayutin or his help with testing the problems and preparing the round, and to the team of testers: MrPaul_TUser, Stresshoover, Supermagzzz, artsin666, defolaut, Peinot, PrianishnikovaRina, sladkayaKlubnichka, Ivan19981305, lankin.i, Pavlova, Decibit, dmitrii.krasnihin, AlexSap, unreal.eugene.

Scoring distribution: 500 — 1000 — 1250 — 1750 — 2250 — 3000.

Good luck!

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By kevinsogo, history, 44 hours ago, In English,

Hello, Codeforces community!

I'm glad to invite you to Codeforces Round #607 (Div. 1) and Codeforces Round #607 (Div. 2), which will be held on Dec/15/2019 08:05 (Moscow time). The round will be rated for both divisions.

The problems were taken (mostly) from the 2019 ICPC Asia-Manila Regional Contest that's happening at the same time. Thus, they have been prepared by various setters and testers from the Philippines: myself (kevinsogo), Kyle See (kylesky), Payton Yao (noobcake), Tim Dumol (timd), Guissmo Asuncion (guissmo in HackerRank) and Marte Soliza (myrtactle in TopCoder).

Since the problems are based on the ICPC Manila regionals, we request all the coaches onsite to refrain from making the problem set public. We also request the coaches and everyone else who has seen the problems (or part of it) to refrain from joining this round.

A huge thanks to isaf27 for coordinating and helping me set up this round. Thanks to 300iq for some testing. Of course, thanks as well to MikeMirzayanov for providing us Codeforces and Polygon. These are great gifts to the competitive programming community! Also, thanks for the opportunity to use our problem set for a CF round.

You will be given 6 problems in both divisions and 2 hours to solve them. I recommend reading all the problems; they were written by talented writers from the judging team.

Good luck, have fun, and I wish everyone high ratings!

The scoring distribution will be announced closer to the beginning of the round.

Update: The scoring will be as follows:

Div.2: 500 — 1250 — 1500 — 2000 — 2500 — 3000 Div.1: 500 — 1000 — 1500 — 1750 — 2250 — 3000

Good luck and have fun!

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By MikeMirzayanov, 4 days ago, translation, In English,

This weekend, on Dec/14/2019 14:05 (Moscow time) we will hold Codeforces Round 606. It is based on problems of Technocup 2020 Elimination Round 4 that will be held at the same time.

Technocup is a major olympiad for Russian-speaking high-school students, so if you fit into this category, please register at Technocup 2020 website and take part in Technocup 2020 - Elimination Round 4.

Problem authors are me, Endagorion and voidmax. Many thanks to the testers: Kostroma, grumpy_gordon, Supermagzzz, AdvancerMan, Stepavly, unreal.eugene, cannor147 and geranazavr555!

Div. 1 and Div.2 editions are open and rated for everyone. As usual, the statements will be provided in English and in Russian. Register and enjoy the contests!

Good luck on the round

UPD 1: The scoring:

  • D1: 500-1000-1250-2000-2250-3000
  • D2: 500-1000-1500-1500-2000-2500

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By niyaznigmatul, 4 days ago, translation, In English,


The second qualifier to Innopolis Open 2020 rescheduled to December 14th 1:00 PM UTC.

Qualifier duration is 5 hours, there are five problems in the contest. Those, who scored high enough, will be invited to the final contest that takes place on February 22-23, 2020. Those, who already qualified, can compete in second qualifier as well, but they won't influence qualification.

Innopolis Open is only for middle and high school students. All others will be able to solve the problems in Codeforces::Gym.

There is a trial round taking place, it ends in the evening of December 13. If you are new to Innopolis Open it's good to take part in trial round to get to know the testing system and format of problems. Be careful, the trial round and qualifier don't take place on Codeforces website. To take part in the trial round or the qualifier you are required to sign up on Innopolis Open website. Don't forget to read the rules and the testing system guide on the website.

First qualifier took place several weeks ago, you can try to solve the problems in Codeforces gym: Innopolis Open 2019-2020, qualification, contest 1.

Previous year contests. Be careful, some of them may be in ICPC format:

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By Vovuh, history, 5 days ago, translation, In English,


Hello! Codeforces Round #605 (Div. 3) will start at Dec/12/2019 16:35 (Moscow time). You will be offered 6 or 7 problems (or 8) with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have rating 1600 or higher, can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 or 7 (or 8) problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

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 participants of the third division, you must:

  • take part in at least two rated rounds (and solve at least one problem in each of them),
  • do not have a point of 1900 or higher in the rating.

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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of my work. Thanks to my good friends Daria ZeroAmbition Stepanova, Mikhail PikMike Piklyaev, Maksim Ne0n25 Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

I also would like to say that participants who will submit wrong solutions on purpose and hack them afterwards (example) will not be shown in the hacking leaders table.


UPD: Great thanks to Artem rox Plotkin and Dmitrii opukittpceno_hhr Umnov for testing the round and help with bugs fixing! Artem is also proposed one of the problems for today's round!

UPD: Editorial is published!

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By chemthan, 12 days ago, In English,

Hello everyone!

I am glad to invite you to Codeforces Round #604, which will take place on Dec/05/2019 17:35 (Moscow time). The round will be rated for both divisions.

Exactly 300 Codeforces rounds passed since my first one (Round 304). I have learned a lot of things here and have much fun in participating in the competitions. Now, I want to contribute to this community by proposing some problems. I hope that you will find something interesting in solving them.

The contest is prepared by me, laoriu, I_love_Hoang_Yen, coordinator isaf27 and CF admin MikeMirzayanov. As usually, we must specially thank to below people who make contest possible:

There will be roughly 6 problems in each division. Scoring will be announced later.

GL & HF! See you on the scoreboard.

UPD 1: Scoring

  • D1: 500 1000 1500 (1000+1000) 2250 3000.
  • D2: 500 1000 1500 2000 2000 2500.

UPD 2: Thanks for participating! Congratulations to the winners!

Top 5 Div1:

Top 5 Div2:

UPD 3: Sorry for delay, this is editorial.

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By kuviman, 13 days ago, translation, In English,

Hello everyone!

Mail.Ru Group announces start of the annual artificial intelligence programming championship — AI Cup 2019.

AI Cup — open artificial intelligence programming contest. Test yourself writing a game strategy! It’s simple, clear and fun!

This year's theme is — platformer. We are waiting for you on our site! The site is already open, you can start implementing your strategies.

Eighth AI Cup championship is named CodeSide. You are to program an artificial intelligence to control a team of units. Your strategies will compete with each other in the Sandbox and the championship. Currently availiable programming languages: C++, C#, F#, D, Go, Java, Kotlin, Scala, Python, Ruby, Rust. The Sandbox is already open. Good luck!

Currently the championship is in beta-test mode, and on December 7th Sandbox will start working officially!


  • Sandbox: open for everyone from November 27; until December 7 will be beta-testing, system instability and significant changes in the rules are possible during this period.
  • Round 1: December 14-15.
  • Round 2: December 21-22.
  • Finals: December 28-30.


  • 1-st place — MacBook Pro 15
  • 2-nd place — MacBook Pro 13
  • 3-rd place — Apple iPad
  • 4-th place — Samsung Gear S3 or Apple Watch S4
  • 5-th place — WD My Cloud 6 TB
  • 6-th place — WD My Passport Ultra 4TB

Moreover, the top-6 sandbox winners will get WD My Passport Ultra 2TB. All participants in the Round 2 will get T-shirts, and the participants of the Finals will get hoodies.

Begin from the Quick start guide. Writing a simple strategy is not hard at all!

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