By BledDest, history, 16 hours ago, In English,

Hello Codeforces!

Good news! Harbour.Space is supporting the return of a new series of educational rounds on Codeforces! You can read the details in the blog post.

On March 27, 17:35 MSK will be held Educational Codeforces Round 18.

You will be given 6 problems and 2 hours to solve them. We hope that everyone, both novices and experienced coders, will find something interesting in this contest. The contest will be unrated.

The round was prepared by Mikhail PikMike Piklyaev, Mikhail MikeMirzayanov Mirzayanov and me.

Wish you enjoy the contest! Good luck!

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By MikeMirzayanov, 44 hours ago, translation, In English,

Hello Codeforces!

I am pleased to announce a long term partnership with Harbour.Space University and Codeforces.

Harbour.Space is supporting the return of a new series of educational rounds on Codeforces!

They will take place with the regularity of ~2 times per month with the first round on 14:35 UTC, 27th of March, 2017.

Education Rounds Rules:

  • Scholarships to study Data Science, Computer Science and Cybersecurity in Barcelona for best performing participants, courtesy of Harbour.Space University (more details later!);
  • Classic Duration: 1.5 — 2.5 hours;
  • The goal is rather to practice and to educate, than to compete;
  • Not only problems, but also exercises can be used;
  • Useful, even well-known ideas can be reused in order to introduce them to a wide range of participants;
  • Unrated (perhaps only for now);
  • We will conduct them in the ACM-ICPC mode;
  • The results that are obtained after the end of the round, are preliminary;
  • After the end of the round will be a 24-hour period of open hacks — any visitor of Codeforces may try to hack any complete solution to a problem of the last round (either from a contest, or from practice), the source code of hacking solution is available (you can copy the text and, for example, stress it);
  • All successful hacks from the previous item will be added to the official test set and after as long as 24 hours after the end of the round retesting of all complete solutions will be made;
  • Only after the final standings based on improved test data, the results are final;
  • Our ability to process such problems are limited, so actually the test suites from the jury are expected to end up incomplete — we are looking forward to your hacks!

In February I had a new and wonderful experience of coaching top teams at the Barcelona ACM-ICPC Bootcamp hosted by Harbour.Space University. I was really impressed by the university, participating teams and fellow coaches from our community such as Endagorion, GlebsHP, Michael, Jacob and snarknews that were also there.

During the bootcamp it became clear to me that Harbour.Space University is a new type of university that’s reinventing the university experience. It is a modern, adaptable and flexible university that is doing amazing things in preparing talented students for careers in Computer Science, Data Science and Cyber Security.

All of their programs are developed in collaboration with the industry and are taught by the top professionals in the respective fields such as Viktor Kantor, Edith Elkind, Alexander Kulikov, Alex Dainiak, Sergey Nikolenko, Deepa Gupta and many others. I am delighted to be joining Harbour.Space fantastic faculty. Together we are developing a series of courses on competitive programming in addition to the bi-annual ACM ICPC Bootcamp that will be hosted by the university in Barcelona.

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

Hello Codeforces, and happy Nowruz.

It's an honor to announce you that Codeforces Round #406 is going to take place on March 23rd.

I'm the writer of this round and it is gonna be my 6th CF contest (there are still plenty coming...). There are 5 problems and you'll have 120 minutes to solve them.

I'd like to thank keyvankhademi and waterfalls for testing this round, netman and KAN for helping me prepare this round and MikeMirzayanov for awesome platforms of Codeforces and Polygon.

The main characters of this round are going to be Rick and Morty!!!

Scoring will be posted soon.

Problems are sorted by their expected difficulty, but I strictly recommend you to read all the problems.

GL & HF!

P.S: Top IOI 2017 participant in each division (only with handle present in the future IOI handle list) will be rewarded with special Persian souvenirs in Tehran.

UPD: Scoring distribution is: 500, 1000, 1750, 2000, 2500 for Div.2 and 750, 1000, 1500, 2000, 2500 for Div.1

UPD: Editorial is out!

UPD: System test is over, congratulations to the winners.

Div.1 winners are:

  1. moejy0viiiiiv
  2. Um_nik
  3. LHiC
  4. -XraY-
  5. ershov.stanislav

Div.2 winners are:

  1. xumingkuan
  2. HXLLL
  3. Rpd-Strike
  4. U6121071173
  5. VoteBanned

See you next time ;)

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By RussianCodeCup, 12 days ago, translation, In English,

Hi, everyone!

We are pleased to announce Russian Code Cup 2017! Qualification rounds will start in April, the Final round will be held online in September. Each of the three Qualification rounds will allow 200 participants to qualify for Elimination round, top 50 from Elimination round will proceed to Final round. The problems will be both in Russian and in English.

The full schedule of the tournament can be found at, you can also register there. Note that you must register for the new season even if you took part in the previous tournaments.

We still have more than two weeks before the first Qualification, so we would like to invite everyone to the warm up round that will take plance on Sunday, March 19, 14-00 Moscow time. Visit to take part in the round, it will be 2 hours long.

Good luck to everyone and see you at Russian Code Cup 2017!

UPD: We remind you that the Warmup Round will start at 14-00 Moscow time. Problems of the Warmup Round are based on IOIP problems (Russian contest for high school students, run today at several cities) that are prepared by the same team of authors. We kindly ask students that take part in IOIP to play fairly and not to try to take part in RCC Warmup. Good luck to everyone!

UPD2: Thanks to all participants that made a real stress testing for our judging machines. Unfortunately we had long queues during the first hour, they were fixed, and from the middle of the contest the waiting time in most cases was limited to 2-3 minutes. We will make sure there would be no queues during further rounds.

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By Errichto, 10 days ago, In English,


The round 1 of VK Cup 2017 will take place on March 18 at 18:35 MSK (check your timezone here), along with standard div1+2 Codeforces Round #405. The contest "VK Cup 2017 — Round 1" is for teams qualified from two Qualification Rounds. The top 400 teams will advance to the Round 2, while other ones will have one more chance in the Wild Card Round 1 in April. Those who don't participate in the VK Cup can take part in the Codeforces Round #405 individually (problems will be available in English too). All three rounds last 2 hours, and all are rated.

I want to thank: KAN for his help in the contest preparation, MikeMirzayanov that we are here, AlexFetisov for testing, the VK company for this nice annual contest.

I'm a setter and I hope (and expect?) that you will enjoy the problems. During the contest, remember that you can read many problems and try to solve those that fit you most.

I wish you great fun and no frustrating bugs.

div2: 500-1000-1500-2000-2500
div1: 500-1000-1500- 2250 -2500
vk-cup: 250-500-1000-1500- 2250 -2500

The contest is over. See the editorial here. Congratulations to all who advanced to the next round, and congratulations to winners of each contest.

Specifically, the winners of VK Cup Round 1 are:

  1. Zlobober, zemen
  2. LHiC, V--o_o--V
  3. Arthur, kefaa
  4. map, Babanin_Ivan
  5. felix, Trumen

The winners of parallel rounds are:

Div. 1:

  1. -XraY-
  2. Laakeri
  3. lewin
  4. dotorya
  5. RAVEman

Div. 2:

  1. rupxup
  2. YES_RPG
  3. T0RRES
  4. HXLLL
  5. Diversity

I'm sorry for letting some slow solutions pass in the Rectangle Strips problem. I tried really hard to prepare tests there but apparently didn't succeed.

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Announcement of VK Cup 2017 - Round 1
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By alex256, history, 13 days ago, translation, In English,

Hello, Codeforces!

Tomorrow, in March 15, 2017 at 18:05 MSK a regular rated Codeforces round for participants from the second division will take place. As usual, participants from the first division can take part out of competition. It's my second contest and I hope you'll like it more than my previous one.

As usual, there will be five problems on the contest and two hours to solve them. I advice you to read all the problems' statements attentively. Also check all your solutions for correctness even if they passed all the pretests. Verdict Pretests passed doesn't mean that the solution is completely correct! I wish you to enjoy the contest and learn something new solving the problems.

Like in the last time, the problems will be about Anton and his friends.

Great thanks to Alexey Vistyazh (netman) for help in preparing the contest, Vladislav Vishnevsky (Vladik) for testing the round, Dmitry Klebanov (dakdima) for reading the statements carefully, and of course, Mike Mirzayanov (MikeMirzayanov) for the great platforms Codeforces and Polygon.

Scoring distribution is 500 — 1000 — 1500 — 2250 — 2500.

UPD. The contest is over, system testing has already started, the editorial will appear soon.

UPD2. Editorial has arrived.

UPD3. Congratulations to the winners of the contest!

Div. 1

  1. uwi
  2. rajat1603
  3. SaSa
  4. mr.banana
  5. Kaban-5

Div. 2

  1. liu_cheng_ao
  2. Gauss
  3. binsjl
  4. hotwater
  5. mister_dudec

Thanks everyone for participating :)

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

Hello everyone!

It looks like there are a lot of Facebook users on Codeforces. But they could not easily authorize with their Facebook account until now. Well, now they can!

You can connect your Codeforces account with your Facebook account on profile settings page:

Just click the connect/update button, allow Codeforces to have access and save settings.

Besides that method, you can also connect your accounts while authorizing — if your Facebook account is not yet connected, you will be asked to either create a new account or to connect it with existing one.

To connect with an existing account you will need to log in using already known method.

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

Hello, Codeforces!

In the lead-up to the ACM-ICPC World Finals we invite everyone to participate in Moscow Pre-Finals ACM ICPC Workshop, that will be held 10-17 of April 2017 at the campus of the Moscow Institute of Physics and Technology ( MIPT). The event is organized by one of the leading Russian universities, MIPT and ITMO.

The Moscow Pre-Finals ACM ICPC Workshop is the unique event in the world of competitive programming. Every year teams from 20 different countries from Europe, Asia and the USA meet at one platform. Many teams participated in this Workshop turn out to be the prize-winners and winners of the the ACM-ICPC World Finals. In 2016 8 out of 13 teams that were awarded medals at the Finals took part in the Moscow Pre-Finals Workshop ACM ICPC at MIPT.

This year the organisators have made possible the remote participation which includes: 2 consultations (1,5 hour each); access to the contests; access to the contest-analysis; electronic certificate for the team; the lower price: the cost for one teams is 1300$. If you want to participate remotely or you have any questions, write here:

The Workshop is going to be held in accordance with the two divisions scheme. We invite finalists to participate in the first division (Div.A) and other teams who want to train before the next season in the second division (Div.B). The official language is English.

The participation cost for one person is $590. The cost includes the full curriculum, food and accommodation at the MIPT campus, as well as the sports and sightseeing schedules on days-off. Registration is here

Also, before the Workshops, we invite the teams of division B to participate for free in the contest, which gives you the discount on participation in Moscow Pre-Finals ACM ICPC Workshop! (1st place — 50% ; 2nd place — 30%; 3d place — 20%)

UPD Thanks to all the participants and our congratulations to the winners!

1 Samara U 2

2 Lords of (the) Homeless

3 Daddys

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