Thanks for the participation!

Hello! Codeforces Round 954 (Div. 3) will start at Jun/23/2024 17:50 (Moscow time). You will be offered 7 problems 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 a rating of 1600 or higher, can register for the round unofficially.

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.

You will be given 7 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for the wrong submission in this round 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 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 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.

The tasks were created and prepared by 74TrAkToR. I would like to thank everyone who helped me a lot with round preparation.

• Coordinator Vladosiya for excellent communication and brilliant coordination of the round!
• Testers veleboks, iNNNo, Sk0rlupka, sharkycode, Noobish_Monk, meowcneil, Matrosk1n, sumit_kk10, Sonya_2009, FelixArg, KirillKhalin, viteli, zwezdinv, EJIC_B_KEDAX, _why_not_, detective...dots, Leeda, windreaper for high-quality testing and valuable advices!
• MikeMirzayanov for amazing Codeforces and Polygon platforms!

Good luck!

UPD: Editorial

UPD: Video Editorial

I understand that you are unhappy with my rounds. And I can try to understand what the precedent is.

You think the problems are math. Understand, I don’t like mathematics, but I can solve the problems that are offered to me. There may be other reasons, we have testers for this and they give us all the necessary advice.

About the last round. I apologize to everyone for what happened. We decided to change problem A at the very last moment so that everyone could pass it. Initially, we had a tested problem, but it was more difficult than task A. Problem G was my authorship and there was an error in the author’s solution. I made the weight restrictions greater than int and did not change the data type in one place. This influenced the answer. We asked problem H from other authors and, unfortunately, it turned out to be known. We removed two G problems because they were famous (one was removed because it was in the 1986 Olympiad), but we did not notice this.

I apologize to the entire community for this incident. You don't deserve this and we put a lot of effort into making this round happen. Now this is all history. Happy New Year everyone and I wish you all the best!

Thanks for the participation!

Thanks for the participation!

Hello, Codeforces!

We are happy to invite you to our experimental round for three divisions, which will take place at Oct/22/2023 14:05 (Moscow time). Please note the non-standard start time for the round. Each division will have 5-7 tasks. The round will be held according to the Codeforces rules and will be rated for all three divisions. A few changes regarding the ratings of participants in this competition:

• In Div.3 the rating of participants is less than 1600.
• In the Div.2 ranking, participants range from 1600 to 2099.
• In Div.1 the rating of participants is no less than 2100.
• Please note that after Codeforces Round 904 (Div. 2) the rating will not be recalculated until the end of this competition.

Let us note that two team Olympiads will be held in parallel on this day and the rounds are based on their tasks:

• XXI Moscow Team Olympiad, high school students competition based in Moscow that is an elimination contest for All-Russian Team Olympiad.
• III Open Team Olympiad UMSh in programming.

We would like to thank everyone who helped me a lot with round preparation.

• Coordinators Artyom123 и Vladosiya for excellent coordination and useful advice.
• Problem authors 74TrAkToR, Mangooste, TheEvilBird, Tikhon228, teraqqq, valerikk, Dmitry07.
• Testers pavlekn, zwezdinv, plagues, SashaT9, Maks_Simenkov, orolik, tmari_sun, OR_LOVe, _why_not_, TimVen74, zarubin, myav, ctraxxd, Gassa, OAleksa, Acanikolic73, AndrewPav, AlphaMale06, NemanjaSo2005, dorijanlendvaj, defnotmee, meOwO, Umi, CIXTEEN, golions, MagentaCobra, FairyWinx, v0s7er, adepteXiao, induk_v_tsiane, Alexdat2000, Be_dos, mr.kolya, kevinxiehk, alexxela12345, talant, daubi for high-quality testing!
• MikeMirzayanov for amazing Codeforces and Polygon platforms.

We wish you good luck and high rating!

UPD: One of the problems will be interactive, so please read guide for interactive problems before the contest.

UPD: Score distribution:

• Div.3: $$$500-1000-1500-1750-2500-2750-(1750+2000)$$$
• Div.2: $$$250-500-1000-(750+1250)-2250-2750$$$
• Div.1: $$$(250+500)-750-1000-1250-2000-2750$$$

UPD: Editorial

UPD: We will retest the solutions to the problem div3F and div2C. This may make minor changes, the rating will be recalculated later.

UPD: Retesting took several minutes. Now all the results are correct :)

Hello, Codeforces!

I am happy to invite you to my Codeforces Round 904 (Div. 2) which will be held at Oct/22/2023 10:05 (Moscow time). The round will be rated for all the participants with rating strictly less than 2100.

The tasks were created and prepared by 74TrAkToR. I would like to thank everyone who helped me a lot with round preparation.

• Coordinator irkstepanov for excellent communication and help with preparation.
• Testers Golovanov399, tibinyte, Silver_Fox, azureglow, eeeDA, coder8080, valeriu, XaRDKoDblCH, cristi_tanase, pshat, Vladosiya, DIvanCode, nnv-nick, priyanshu.p for high-quality testing and valuable advices.
• AlFlen for the idea of one of the tasks and two wonderful years together!
• All members of the jury of the team Olympiad CheReKoSH, because the round is made up of the tasks of this Olympiad.
• MikeMirzayanov for amazing Codeforces and Polygon platforms

During the round you will need to solve 5 problems. You will have 2 hours to solve them.

Score distribution: $$$500-1000-1750-2500-3000$$$

We wish you good luck and high rating!

UPD: Editorial

Thanks for the participation!

Hello, Codeforces!

I am happy to invite you to my Codeforces Round 830 (Div. 2) which will be held at Oct/23/2022 13:05 (Moscow time). The round will be rated for all the participants with rating strictly less than 2100 before Oct/23/2022 10:50 (Moscow time).

The tasks were created and prepared by 74TrAkToR. I would like to thank everyone who helped me a lot with round preparation.

• Coordinator Artyom123 for excellent communication and help with preparation.
• Testers gisp_zjz, Pointy, aaaaawa, feecIe6418, nnv-nick, xiaoziya, Ormlis, huangzirui, Chenyu_Qiu, triple__a, gyh20, low_, voventa, tibinyte, Mr.Robot_28, Qingyu, RUSH_D_CAT, physics0523, Lucina, Rhodoks, Tekor, Milesian, Kalashnikov, Lokeo, mejiamejia, TomiokapEace, Chenyu_Qiu, AquaMoon, MagicalFlower for high-quality testing and valuable advices.
• As well as the testers who tested the CheReKOSH Team Olympiad — it was from the problems of this Olympiad that the round was composed: orz, DIvanCode, CAMOBAP31.
• MikeMirzayanov for amazing Codeforces and Polygon platforms.

During the round you will need to solve 5 problems, some of which have subtasks. You will have 2 hours to solve them.

Score distribution will be announced shortly before the round.

We wish you good luck and high rating!

UPD: Score distribution: $$$750-750-(1000-1000)-(1250-1250)-3000$$$

UPD: Editorial

Hello! Codeforces Round 828 (Div. 3) will start at Oct/16/2022 17:35 (Moscow time). You will be offered 6-8 problems 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 a rating of 1600 or higher, can register for the round unofficially.

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.

You will be given 6-8 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for the wrong submission in this round 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 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 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, pashka for help with ideas for problems and for coordination of my work. Problems have been created and written by MikeMirzayanov, 74TrAkToR and pashka.

We would like to thank: Gornak40, meowcneil, Vladosiya, senjougaharin, efimovpaul, powergee101, tanus_era for testing the contest and valuable feedback. List of testers will be updated.

Good luck!

UPD: Editorial