We are announcing the annual Yandex.Algorithm 2017 championship! This is a great opportunity to compete with the strongest programmers of the world, win a fancy T-shirt, visit Yandex office or even receive some serious money prize.

Hi all!

Tomorrow, on April 5th 2017, at 15:35 UTC the first Wild-card Round of VK Cup 2017 will be held. Along with it there will be parallel unofficial round in which everyone can take part.

The rounds will use special rules, the rounds will be unrated. The problems were prepared by Codeforces team.

The detailed rules will be added to this post 30 minutes before the rounds. I can say now that there will be 24-hours open hacks phase after the round, like in Codeforces Educational Rounds.

Round rules:

The round will be almost usual contest with ACM ICPC rules. There will be 12 problems for 2 hours. During the round your solutions will be tested on some basic tests, they should be much stronger than usual pretests. After the round you will have 24 hours to find tests against other participants’ solutions, this part is the same as in Educational rounds. After that we will add all succesful hacks and our tests and rejudge all submissions. Then the results will be final.

The main difference between ACM ICPC rules and this round is the following rule.

You should submit each problem in a unique programming language. Different compilers of same language are considered the same language. For example, GNU G++, GNU G++ 11, GNU G++ 14 and MS C++ compilers are C++ language. Thus, you are not only to solve problems, but also try different and new for you languages. We don’t think you know 12 languages, we hope that you will quickly learn some basic syntax.

Formally, the following check is performed when you submit a task:

• If there is at least one submission in queue or submission that passed at least one test for this problem in another language, your solution will be ignored. Thus, if your program passes at least one test, you can only solve this problem using this language.
• If there is at least one submission in queue or submission that passed at least one test for another problem in same language, your solution will be ignored. Thus, you can’t use a language for more than one problem.

Remember that you can view filter status of some other round by language and view submissions in a specific language. Also, you can view examples of codes in any of the supported languages on the table below. Also, the table contains the groups of compilers considered the same language.

You can use “custom invocation” tab to run a solution if you don’t have the compiler locally.

The main rules of ACM ICPC contest: each problem can either be completely solved (when all tests are passed), or not solved. The participants are ranked by the number of solved problems, in decreasing order, in case of a tie they are ranked by penalty time. The penalty time is the sum among all problems the time in minutes that had passed between the start of the round and the moment the problem got solved, plus 20 minutes for every rejected submission. Note that the problems are not arranged by difficulty. Also, you can resubmit a solution even if it passed all tests, because there will be more tests after the open hacks.

Good luck!

Open hacks phase has ended, the solutions are rejudged. Congratulations to winners!

Official round:

1. StarScreamOwl, ednotdead
2. VernitaGreen, svxf
3. gars, Provet
4. Me-and-Myself, ultizet
5. svetlana_lana, GoldenMan

Open mirror:

1. Lewin
2. oversolver
3. uwi
4. ifsmirnov
5. Tinsane

Hi, everyone!

This Sunday, April, 2 at 19-00 Moscow time the First Qualification Round of Russian Code Cup 2017 will take place. 200 top participants will qualify for the Elimination Round, those who wouldn't qualify can still take part in two following qualification rounds.

We have a news for you: we have added Kotlin, Haskell and Free Pascal to our list of programming languages, also you can now submit your Python programs to run in PyPy. Exact versions of compilers and compilation commands are published at the official web site. We are working on adding more programming languages.

Good luck to everyone and see you at http://russiancodecup.ru!

UPD Editorial is published

The contest is over; I hope you've enjoyed it :-) Editorial is here.

The fifth April Fools Day Contest will take place on Friday March 31st. This is a joke competition in which solving the problem is often easier than figuring out what the actual task is. Thanks to kit1980 and Codeforces team for their help in preparing problems!

In this round you'll be given 7 weird problems and 2 hours to solve them. The contest will use ACM ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them), and it will be unrated. You can submit solutions in any language allowed by Codeforces. To get an idea of what the contest will look like, you can check out the contests of the past years: 2012, 2013, 2014, 2016.

Be warned, to enjoy competing in this round you'll need a sense of humor compatible with mine! Good luck, and have fun!

Hello everyone!

Codeforces Round #407 for both divisions will happen on Mar/29/2017 19:05 MSK.

The problems were prepared by me (Ihor Barenblat), Stanislav giraffeh Tomash and Anton arsijo Tsypko. Great thanks to Ivan Fekete Fekete, Adalbert Adalbert Makarovych, Roman chakred_namor Derkach, Vladislav winger Isenbaev and Alex AlexFetisov Fetisov for testing the round, Nikolay KAN Kalinin for his help with the round preparation and Mike MikeMirzayanov Mirzayanov for the Codeforces and Polygon systems.

As usual, contestants will have 2 hours to solve 5 problems. Scoring will be announced closer before the round.

Hope that everyone will find interesting problems. Good luck!

Scoring distribution:

Div2: 500-1000-1500-2250-2500

Div1: 500-1250-1500-2000-2250

UPD. Editorial is published.

Congratulations to winners:

Div.1:

1. -XraY-

2. Um_nik

3. jqdai0815

4. YuukaKazami

5. Syloviaely

Div.2:

1. KacaMG00

2. LAGBOYDaD3zZ

3. __W__

4. GoogleBot

5. shas20

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 awoo Piklyaev, Mikhail MikeMirzayanov Mirzayanov and me. We'd like to thank Maxim HellKitsune Finutin and Alexey ashmelev Shmelev for testing the round.

Wish you enjoy the contest! Good luck!

UPD: Editorial.

UPD2: All successful hacks have been added to the testsets, all submissions have been rejudged. Thank you for participating in the contest!

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.

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. jqdai0815
2. Um_nik
3. LHiC
4. -XraY-
5. ershov.stanislav

Div.2 winners are:

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

See you next time ;)

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 http://russiancodecup.ru, 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 http://russiancodecup.ru 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.