By huawei, 3 weeks ago, In English,

Dear Friends!

If you dream of realizing your ideas in new technologies and products used by a third part of the world's population — join Honorcup Marathon. It will be an unrated round for individual participation, as well as for teams of up to three people.

Take part in the round →

You will develop a quite challenging task without exact solution. Your solution with show up your programming skills, research and data analysis abilities.

At stake: we have Huawei devices for the top 3 winners, as well as 10,000 USD for top 1.

And, of course, TOP 80 participants will get a hoodie with Huawei Codecraft logo! During registration don’t forget to mention your size and home address for delivery. Well performed participants will be invited to get highly paid 3 months contracts in Moscow, St. Petersburg, Nizhny Novgorod, Novosibirsk, Minsk or in China (including transportation & accommodation expenses covered).

We accept solutions before October 14th, 20.59.59, (Moscow time).

We will ask winners to provide the source code and description of the solution; the details can be discussed in a phone call. In case of reasonable doubt about the violation of the rules, we reserve the right to transfer the prize to the next participant. Thank you for understanding!

Don’t miss your chance. Good luck to all!

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Announcement of Huawei Honorcup Marathon 2
Announcement of Huawei Honorcup Marathon 2
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By fortune, history, 3 weeks ago, In English,

Hi folks,

The problem set from 2019 Fall Waterloo Local Contest that was held this Sunday will be available in the gym today in roughly 8 hours (timedate link).

This is an individual contest that contains 5 problems with 3 hours to solve them. It's good for both div 2 and div 1 participants — at least 3 problems should be accessible for div 2.

Div 1 participants are especially invited to solve problem E — so far only three people solved E.


UPD: Registration is open

UPD: Solution sketches are available at

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By McDic, history, 3 weeks ago, In English,

다시 만나서 반가워요, 코드포스! (Nice to see you again, Codeforces!)

I'm again happy to introduce you to Codeforces Round #589 (Div. 2). Please look at following information for details:

  • This contest will take place on Sep/29/2019 16:05 (Moscow time).
  • The round will be rated for all Division 2 participants.
  • There are 6 problems and you will have 2 hours to solve them. Score distribution will be announced later.

The listed handles below are contributors. Thank you for all who listed!

For this contest, I tried to improve following things:

  • Reasonable difficulty: At my last contest, less than 200 official participants managed to solve at least one of DEF. Especially, 1182D's problem difficulty rating is 2500 and 1182F's problem difficulty rating is 2900(no official solvers!). This is not good for Div.2 participants. In other words, my first contest was hell. So this time, I tried to make my second contest to have more reasonable difficulty than my first contest.
  • Stronger data: There were 300+ successful hacks and almost 2000 sysfails at 1182B. At this time, I splitted testing phase into early phase and late phase. I'm bit worried, but I believe data will be stronger than my last contest.
  • Compact statement: I remember many people complained about 1182C's super complex statement. I made very compact statements for this round. There is no problem with more than 10 lines of statement(except I/O section) in this contest.

I hope everyone can enjoy my second contest. Thanks in advance!


  1. If you want to discuss problems in chat after contest ends, come and you can enjoy discussion.
  2. I have deleted my last problem(G) from this contest during testing period. I really wanted to include that beautiful problem in my contest, but nobody solved that problem for a week. That problem will be appeared in another Div.1 contest.
  3. Scoring distribution is 500(A)-1000(B)-1250(C)-1750(D)-2250(E)-2750(F).
  4. Editorial:
  5. Congratulation for winners!

WINNERS (updated):

  1. PositionZero
  2. supy_2
  3. hitman623
  4. lzqaq
  5. skypool
  6. LittleBeetle
  7. Tsypkokokokoko
  8. i_love_gnar
  9. 8-_-8 (handle mentioning is not working on his handle)
  10. wdk1745

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By SoMuchDrama, 3 weeks ago, In English,

Hi everyone!

This summer I participated in the program AddisCoder 2019. It is a five-week intensive summer camp where high school students from different regions of Ethiopia learning the basics of programming and algorithms. Next summer the program will be held as well.

It was an amazing experience because I met a lot of cool and passionate students, teaching assistants and professors. As for TAs, we were working on problems for students, helping them with exercises, giving mini-lectures and had a lot of fun exploring Ethiopia together in our free time.

Students chosen for this program are good. They were selected by the Ministry of Education based on their achievements during studying in high school or applied themselves. Some students never used a computer before the program still being quite good at maths and it was exciting to see their advancement from that level to ability to write some simple algorithms. After the program, they have an opportunity to continue study in the best universities in the world.

One of the organizers of this program is Jelani Nelson. He is a computer science professor who used to compete a lot on TopCoder and now runs this program. Teaching assistants are chosen from all over the world and some of them are also part of the competitive programming community. So I want to inspire you to apply as Reyna did it this year for me.

The exact dates of the program are not chosen yet, but it will likely be the middle of July to middle of August, for 5 weeks. The foundation will cover the flight and the hotel. If you need you can also ask for a stipend.

Apply here:

For more details or some photos you can check out

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By Radewoosh, 4 weeks ago, In English,

Hello everybody! A new round is upcoming and I'm honored to be its author. The round will first appear as the onsite for Dasha.AI Code Championship and later we will hold a rated mirror. Everybody is welcomed to participate in Codeforces and I wish good luck for people in Saint Petersburg and Novosibirsk.

Using the opportunity, I want to thank:

  • mnbvmar for helping in the preparation of a great part of everything. Really, without you, I wouldn't do it.
  • 300iq for coordination and help with preparation.
  • As always, MikeMirzayanov for taking care of international competitive programming and making such great platforms as Codeforces and Polygon.
  • KAN, zscoder, Lewin, JeffreyHo, Darkstalker, Darko and Gtaumaturgo for testing the problems and great advice.
  • Dasha.Ai for an organization and a sponsorship.

Scoring will appear later.

Good luck and see you during the contest!

UPD1a: Scoring in div2: 500-750-1250-1750-2500-3000

UPD1b: Scoring in div1: 500-1000-1500-2250-(1500+1250)-3500

UPD2: editorial

UPD3: Congratulations to the winners!

In div1:

  1. Um_nik
  2. yosupo
  3. ksun48

In div2:

  1. lqs2o15
  2. rainboy
  3. TomiokaGiyuu

In the onsite competition in Saint Petersburg:

  1. aid
  2. V--gLaSsH0ldEr593--V
  3. cookiedoth

In the onsite competition in Novosibirsk:

  1. Timonnable
  2. Pechalka
  3. Maho

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By MikeMirzayanov, 4 weeks ago, In English,


It is not an official announcement of the events. Just information: The contest on 22.09.2019 12:05 (Московское время) will be only for onsite finalists. The mirror round will be the next day on 23.09.2019 17:05 (Московское время).

Hope to see many participants. Guess, who are the main writers of the Final?

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By Vovuh, history, 4 weeks ago, translation, In English,

Hello everyone! This round will be a little bit special because it is composed from the problemset of Saratov school elimination stage to the all-russian olympiad of school students. The problems were invented and prepared by Alexander fcspartakm Frolov, Ivan BledDest Androsov and me, Vladimir Vovuh Petrov. Good luck to everyone!

UPD: Thanks to Daria ZeroAmbition Stepanova and Danila sad101010 Smirnov for testing!

UPD2: We will open solutions to view and start the hacking phase a little bit later because the school elimination stage is not over yet. We will open all in about two hours. Please don't discuss any solutions during next two hours.

UPD3: Now you can discuss problems.

UPD4: Editorial is published!


Hello! Codeforces Round #587 (Div. 3) will start at Sep/21/2019 10:05 (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 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.


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By PikMike, history, 4 weeks ago, translation, In English,

Hello Codeforces!

On Sep/19/2019 17:35 (Moscow time) Educational Codeforces Round 73 (Rated for Div. 2) will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

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 Roman Roms Glazov, Adilbek adedalic Dalabaev, Vladimir Vovuh Petrov, Ivan BledDest Androsov, Maksim Ne0n25 Mescheryakov and me. Also huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

Our friends at Harbour.Space also have a message for you:

Hello Codeforces,

We want to know what you think about Harbour.Space’s involvement in the Codeforces community, and how you believe we can improve.

So we created this short, 5 question survey to hear your thoughts about how we can provide you with more stuff that you’re interested in, so that we can improve your experience on Codeforces.

We really value your feedback, so it would mean a lot if you could take a minute and fill out the survey. Thanks in advance!


Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 kefaa2 7 192
2 jiangly 6 152
3 betrue12 6 187
4 I_love_Tanya_Romanova 6 196
5 pekempey 6 198

Congratulations to the best hackers:

Rank Competitor Hack Count
1 achi_basadzishvili 129:-46
2 apoorv024 87:-4
3 Kolo_Ray7 73:-31
4 lollihunter 52:-7
5 badmofo21 15:-1
544 successful hacks and 568 unsuccessful hacks were made in total!

And finally people who were the first to solve each problem:

Problem Competitor Penalty
A Chereshnya_ 0:01
B Chereshnya_ 0:02
C YahiaAshraf74 0:04
D sysjuruo 0:08
E kefaa2 0:31
F Benq 0:35
G Benq 1:02

UPD: Post about the issue

UPD2: Editorial is out

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By SerezhaE, 5 weeks ago, translation, In English,

Hello Codeforces!

We are glad to invite you to the Codeforces Round 586 (Div. 1 + Div. 2). Yes, it is rated!

The problems were invented and prepared by Alexponomarev7, adamant, lesswrong, wrg0ababd, allrats, I_love_QMsh, msmlkm and me, SerezhaE. A lot of thanks to 300iq and _kun_ for help in contest preparation, and also we want to thank MikeMirzayanov for Codeforces and Polygon systems.

The contest starts on Wednesday, September 18 at 16:05 UTC and you will have 2 hours to solve the problemes. I believe everyone will find interesting problem for themselves :)

UPD. Editorial is published!

Good luck!

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