By 300iq, 3 days ago, translation, In English,


I'm glad to invite you to take part in Avito Code Challenge 2018 which starts on May/27/2018 17:35 (Moscow time). Any participant can join the round and it will be rated for each participant. Hope to see you among the participants!

Problems are prepared by me — Ildar Gainullin.

This round is conducted on the initiative and support of Avito. is a Russian classified advertisements website with sections devoted to general good for sale, jobs, real estate, personals, cars for sale, and services. is the most popular classifieds site in Russia and is the third biggest classifieds site in the world after Craigslist and the Chinese website

Many thanks to Vladislav winger Isenbaev, Grigory gritukan Reznikov, Ivan isaf27 Safonov and Alexander AlexFetisov Fetisov for the round testing, Nikolay KAN Kalinin for helping me to prepare the contest, and also to Mike MikeMirzayanov Mirzayanov for systems Codeforces and Polygon.

Participants will be offered eight problems and three hours to solve them. Scoring will be announced a bit later.

Avito presents nice gifts for participants. Top 30 participants and also 10 random participants with places 31-130 will be awarded with a special T-shirt.

I hope everyone will find interesting problem for themselves. Wish everyone a successful round and high ratings!

Good luck!

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By MikeMirzayanov, 3 days ago, translation, In English,

Hello, Codeforces!

I offer you also to join testing of HTTPS support. Just visit to and start to use the website through HTTPS.

I am aware of some minor issues: mails still refer to the HTTP version of the website, Facebook does not merge likes for HTTP and HTTPS. Have you noticed anything else? Write a comment!

And thanks to Let's Encrypt for the certificates. Now with wildcards!

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By Harbour.Space, history, 3 days ago, In English,

Hello, Codeforces!

We are pleased to announce the 3rd Hello Barcelona Programming Bootcamp in collaboration with Moscow Workshops ICPC, organised by Harbour.Space University with content provided by Moscow Workshops ICPC, in collaboration with Moscow Institute of Physics and Technology, ITMO University, Saint Petersburg State University and Codeforces!

The boot camp will be held from 26 September to 4 October, 2018 in Barcelona, and hosted at the beautiful and technologically mind-bending Media-TIC building — the Smart Building of Tomorrow.

The world's greatest coaches training the participants of Moscow Workshops ICPC events will be attending the programming bootcamp: Mike MikeMirzayanov Mirzayanov, Andrey andrewzta Stankevich, Michael Endagorion Tikhomirov, Gleb GlebsHP Evstropov, Artem VArtem Vasilyev, Ivan ifsmirnov Smirnov and other world renowned Russian coaches. The Chief Judge of the camp is Oleg Snarknews Khristenko. It will be an important opportunity for teams from all over the world to learn from these well-known and successful coaches in the ICPC world.

“The participants are facing the problems from real contests selected by our coaches. In competitive programming it’s very important to have real solving experience: one thing is to be able to solve problems staying in comfortable environment of one’s university but championships are completely different. The only way to get ready for the extreme conditions of ICPC is to visit our programming boot-camps”, says Alexey Maleev, the founder of Moscow Workshops ICPC.

So how do you get the most out of the camp? "I think there is no universal solution for "get the most out of a camp" – everyone should find their own path, but the general guideline will be: communicate with other participants as much as you can, make sure you do upsolving (at least some), keep track of how much you sleep," says Gleb GlebsHP Evstropov, coach.

A look back on our recent boot camp:

“Having visited all the Hello Programming Bootcamps, I left the events feeling inspired from the overall atmosphere. I am sure that all teams received an immense amount of knowledge and skill. As one of the coaches, all of the flattering reviews about the camp from the participants were pleasant for me to hear. I am very glad that these camps are becoming regular. Harbour.Space University and Moscow Workshops ICPC have done a job worthy of admiration!” says Mike MikeMirzayanov Mirzayanov.

The Bootcamp will be split into three divisions:

  • Division A. Designed to prepare students to excel and win medals in the next ICPC World Finals.
  • Division B. Designed to help teams prepare for the next season of ICPC Regionals and international competitions. This is an appropriate introduction for teams and students new to the world of ICPC and competitive programming competitions in general. The Division B curriculum features thematic lectures and contests.

The participation fee is unchanged: €1270 per person (cultural programme, accommodation and half-board meals included). Single participants and teams must register before July 1st, 2018 to receive the 15% off Early Bird Discount, or the 20% off Loyalty Discount, which is awarded to teams that participated in previous Hello Programming Bootcamps or Moscow Workshops ICPC boot camps.

Learn more about Barcelona ICPC Bootcamp

You can ask any questions by email:

In order to experience the atmosphere of the event, we suggest you familiarise yourself with the photos and videos from the previous Hello Programming Bootcamps in collaboration with Moscow Workshops ICPC.

Learn more about Harbour.Space University

Please reach out to us if you have any questions about the university or our programmes:

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By PikMike, history, 6 days ago, translation, In English,

Hello Codeforces!

On May/21/2018 17:45 (Moscow time) Educational Codeforces Round 44 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 extented ACM ICPC rules. After the end of the contest you will have one day 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.

The problems were prepared by Adilbek adedalic Dalabaev, Vladimir Vovuh Petrov and me.

Good luck to all participants!

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 Benq 6 143
2 crhkr 6 202
3 mjhun 6 210
4 nhho 6 210
5 krijgertje 6 223

Congratulations to the best hackers:

Rank Competitor Hack Count
1 step_by_step 248:-25
2 greencis 31:-6
3 zero-light-some 15
4 Necrozma 12
5 Codefocres 11:-1
703 successful hacks and 490 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A dotorya 0:01
B dotorya 0:03
C dotorya 0:10
D Benq 0:21
E SmsS4 0:07
F DarkestLight 0:49
G Marco_L_T 0:44

UPD: Editorial is uploaded

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By erdos, history, 8 days ago, In English,

Code Jam R2 starts in ~24h (Saturday, May 19th 14:00 UTC)

Let's discuss the problems after the contest!

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By AGrigorii, 10 days ago, translation, In English,

Hello, Codeforces!

I'd like to invite you to Codeforces Round #484 (Div. 2). It'll be held on May/17/2018 19:35 (Moscow time) and Div. 1 participants can join it out of competition. Please pay attention that round starts in the unusual time!

Me and Andrey API Pikas prepared the tasks for this round.

Great thanks to Nikolay KAN Kalinin for helping us preparing the contest, to Mikhail MikeMirzayanov Mirzayanov for the great Polygon platform and Codeforces and also to Kirill KittyLover Samelyuk, Nikolay Apollon76 Permyakov, Dmitry Krainov_Dmitry Krainov, Andrey GreenGrape Rayskiy and Alexey Um_nik Danilyuk for writing solutions.

You'll have to solve six tasks in two hours. The scoring distribution will be announced later

Good luck!

UPD Score distribution 500-1000-1500-2000-2500-3000

UPD2 Congratulations to the winners of the division 2:

  1. Kotori_Is_My_Wife

  2. vosptu

  3. ez_zkj

  4. relativity

  5. iordache.bogdan

And also our congratulations to the winners of both divisions:

  1. Claris

  2. Benq

  3. Kotori_Is_My_Wife

  4. kmjp

  5. vosptu

UPD3 The editorial will be published tomorrow.

UPD4 Editorial

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By Livace, 12 days ago, In English,

Hello, Codeforces!

Codeforces Round #483 will take place on May/15/2018 17:45 (Moscow time). The round will be rated for both divisions.

Problems were prepared by neckbosov, KAN and me.

Many thanks to testers qoo2p5, manoprenko, AlexFetisov, winger, cyand1317 and ashmelev.

Also thanks to MikeMirzayanov for Codeforces and Polygon and ifsmirnov for jngen.

Upd. The scoring distribution is 500-1000-1500-2000-2500 for div2 and 500-1000-1500- 2250 -2500 for div1.

Congratulations to the winners!


  1. fateice
  2. skuecrk
  3. Egor
  4. dotorya
  5. LHiC


  1. wevetriedly
  2. mraron
  3. adeliaut
  4. fengsuiyan
  5. K.F.Cat


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By htoj, 13 days ago, In English,

Hi Codeforces!

Sorry for being late for the announcement.

I'm glad to introduce to you my first contest Codeforces Round #482 (Div. 2). It will take place on May/14/2018 17:35 (Moscow time).

You will have 5 problems and 2 hours to solve them.

The problems were prepared by me (Quyen Dinh), _Kuroni_ (Trung Dang) and _Shirone_ (Lam Le) with suggestions from FallingStar1709 (Nhat Hoang) and HaiDang2001VN (Dang Huynh). I would like to thank KAN for his great help in checking the problems and giving comments, Tommyr7 for testing all the problems and MikeMirzayanov for the awesome Codeforces and Polygon platform.

Note that the round is rated for everyone with rating below 2100.

In this contest, you will meet Kuro, Shiro and Katie, the three naughty but smart cats who love asking thought-provoking questions. I hope you will find our problems interesting. Good luck to you all!

UPD: Also big thanks to cyand1317 for helping us with the problems and arsor for translating the problems into Russian. Sorry, I forgot you guys.

UPD2: The scoring distribution is 500 — 1000 — 1250 — 1750 — 2250. Have fun!

UPD3: Congratulations to the winners!

Div. 1 & Div. 2:

  1. dotorya

  2. mama_budra

  3. coach.31

  4. nuip

  5. kevinsogo

Our top 5 solved all the problems. Awesome!


  1. mama_budra (solved all problems!)

  2. coach.31 (solved all problems!)

  3. Illidan

  4. ranwen

  5. iloveUtaha

Thanks for everything! Here is the editorial.

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By MikeMirzayanov, 2 weeks ago, translation, In English,


Codeforces Round #481 (Div. 3) will start on May/13/2018 12:05 (Moscow time). It will be the second Div.3 round in the history of Codeforces. You will be offered 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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.

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.

The problem are written by me and fcspartakm. Many thanks to testers AGrigorii, BigBag, nhho and Sert!

Good luck!

UPD 1: Thank you for participation. Problem tutorials have been published.

UPD 2: Congratulations to the winners! Top-5 (official standings):

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