Hello!

Here are some statistics about 2015. I'm glad to see our growth. Frankly, each year I'm afraid to see that we stop to grow, but each year I see 20-50% growth! Thank you for your interest :-)

In addition, I have written before about progress in the development and championships and rounds with partner companies in 2015. If you have not read, please read.

Here are the funny pictures with the statistics:

Growth of registerations. This year we overcame 300K users!

Hello!

I congratulate New Year to the entire Codeforces community! I wish you interesting problems, beautiful solutions and successful attempts in the last seconds! I wish not to lose interest in programming, to believe in themselves and regularly find confirmation of this belief. And do not get sick and more smile (even if your rating decreases). Hooray!

The profile settings appear magical section. Happy New Year!

Hi everybody.

The last round of the 2015 will take place on the 30-th of December (starting time). The contest will last 3 hours.

It won't be a usual round. Both divisions will compete together. You will get 8 problems to solve in 3 hours. Points will decrease slower than usually — otherwise you would get eps for solving a problem at the end. Scoring will be announced just before a contest. So will the speed of the points/minute loss.

My goal was to provide you a diverse problemset with interesting problems for all contestants. During a contest you should consider reading not only the next problem but the few next ones.

You will get this round thanks to work of many people. I am a problem setter. GlebsHP helps me with everything (a lot). AlexFetisov, johnasselta and Zlobober are testers (thanks guys!). Delinur translates everything into Russian. Last but not least, MikeMirzayanov provides two awesome platforms — CF and Polygon. And there are so many people involved in Codeforces. Thank you all.

Let me give you more motivation to compete. The New Year is coming for Limak and he needs your help! Limak is a little polar bear by the way. You will help him, won't you?

I wish you great fun and no frustrating bugs. Looking forward to seeing you!

SCORING

Points will decrease with such a speed that submitting a problem at the end would give you the same number of points as in standard 2-hours rounds. Points for problems are 500-750-1250-1750-2500-2500-3000-3500. Enjoy the last contest in this year!

EDITORIAL

Instead of refreshing standings you can read an editorial. I will keep polishing it.

WINNERS

I'm amazed by the number of high-rated participants today. Fight was really tough and winners truly deserve respect.

1. tourist
2. Petr
3. Egor
4. rng_58
5. black_horse2014
6. step5
7. I_love_Tanya_Romanova
8. bmerry
9. W4yneb0t
10. V--o_o--V

It was the last Codeforces round in the 2015. Thanks for participating. And kudos for Mike for creating CF.

I wish you all an awesome year. Let the 2016 be (even) better than the passing year. Cheers.

Hurry! Only until the 10th of January, you can change your handle (but only once)! Note that it will be possible to roll back the changes or change the handle again only after a year. Be careful what you wish for.

You can change your handle to the new one which wasn't used before by anybody or which was used by you before. The links to a profile page with old handle would automatically redirect to the actual profile.

Talking about handles I always reminisce the following story. Once a user wrote me the message: "Please change my handle from I_love_Valya to I_love_Sveta, as I no longer love Valya ..."

Happy New Year!

Hello!

In 2015 we have not only engaged in the organization of rounds and championships. Every day we write the code, debug, test and explore a variety of tools and technologies to make Codeforces better. Even if in some periods you have not seen great changes on the website, it does not mean that the development was stopped — just some of the innovations relate solely to infrastructure, architecture or administrative interfaces and are not visible to the users.

I have collected in a list of all the innovations, which touch users in some sense. This faceless list includes results of many days of work of each member (sometimes with prefix ex-) of Codeforces technical team: MikeMirzayanov, MaximShipko, kuviman, fcspartakm, Avalanche. There are valuable helpers Edvard (helped with the introduction of educational rounds), stingray (constant help with the administration and configuration of servers is priceless), demlit and lthirteenthl (assistance with the administration and hardware). And I just listed those who assist in technical terms — there is an important list of all of those who contributed to the life of Codeforces in other aspects. Thank you!

Here is the promised list of completed (sometimes partially) cases in 2015, the year.

Hello everybody!

I hope you have the holiday spirit!

Later I will publish statistics for the year and tell you about our achievements of this year, and for now I will talk about championships and competitions that we made with our partners in 2015. My speech does not include any activities that we have conducted very far from the Codeforces site (e.g., Russian AI Cup).

This year is remembered by many interesting events that we did not by ourselves, but together with partners. I am particularly pleased that all companies who wished to fill the ranks of their employees found worthy candidates among our members. And someone said that the Olympiads are not needed! That is a lie. Here is the list of events:

VK Cup 2015

Team Championship for young participants, was conducted in Russian. 2349 registered teams of two (rarely of 1 participant). The coolest prize money and rich finals in St. Petersburg. Organizer is the VK company.

Rockethon 2015

Open individual competition by the original rules of the Rocket Fuel company. More than 3600 participants and 6565 registrations!

ZeptoLab Code Rush 2015

Individual competition by the classical rules of the ZeptoLab company. 3090 participants and 5504 registrations, excellent presents for the winners! And insanely beautiful drawings from ZeptoLab artists!

Looksery Cup 2015

! Looksery

Individual competition by the classical rules of the Looksery company. This company did not only congratulate us on our 5th anniversary, but conducted such a cool round. And the fund of the company's founder had very cool initiatives supporting the development of sports programming! 3528 participants and 5714 registrations. Yes, the gifts are yet on the way!

AIM Fund Round 2015

Individual competition in two divisions by the classical rules of the AIM Fund company. Prepared in the context of congratulating Codeforces on the 5th anniversary, thank you! 4064 participants and 6721 registrations. I've heard a lot about the after-party in Petrozavodsk. I wish I had been there!

Call To Code 2015

A competition for Irish schoolchildren by unusual rules. It was not conducted on the Codeforces site, but on our platform. Organized by the Google company.

Traditionally, SnarkNews runs two New Year Contests.

The New Year Blitz Contest (Multiple Language Round) will start at 16:00 31.12.2015 and ends at 08:00 01.01.2016 Moscow Time. Contest will consist of 9-13 problems. Some of those problems are based on problems, used at official or training contests in 2015. Contest rules are based on the ACM system with two important modifications.

1. Penalty time is calculated as distance between time of first successful submit for the contestant on this problem and 0:00:00 01.01.2016, i.e. successful submissions at 23:50:00 31.12.2015 and at 0:10:00 01.01.2016 will both have penalty time 10 minutes (600 seconds).

2. Multiple Language Round rule: If for the first successful submit for the contestant on the some problem was used the programming language, which was never used by this contestant in his previous first successful submits on other problems, contestant receives language bonus: his summary penalty time is decreased by 100 minutes (6000 seconds). Note that different implementations of the same language are counting as same language, i.e. Java 6 and Java 7 are both counted as Java, C++ 32 bit and C++11 64 bit both as C++. Additionally, C and C++ are counted as same programming language.

Contest will be running on Yandex.Contest system. Link for registration and participation.

12'th Prime New Year Contest will start at 0:00 30.12.2015 and finish at 23:50 10.01.2016 Moscow time. Traditionally, Prime New Year Contest consists of problems, which were presented at team programming contests in 2015 and never solved on the contest. For the Prime New Year contest plain ACM rules are used.

Idea of Prime Contest was first implemented by Andrey Lopatin and Nick Dourov at Summer Petrozavodsk training camp at 2003; in Russian word "Prostoj" used in meanings "prime" and "easy", so, contest was called "Prostoj contest" but was composed of extremelly hard problems, numbered with prime numbers (2,3,5 etc). Since then such a numeration is traditionally used for contests, consisting of very hard problems only.

Contest will be running on Yandex.Contest system. Link for registration and participation.

Both contests have English statements.

Hello, Codeforces!

I'd like to invite you to Codeforces Round #337 (Div. 2). It'll be held on Sunday, December 27 at 14:05 MSK (Moscow time) and as usual Div. 1 participants can join out of competition. Note that round starts in the unusual time!!!

Me and Edvard Davtyan (Edvard) prepared the tasks for this Round.

Great thanks to Gleb Evstropov (GlebsHP) for helping us preparing the contest, to Maria Belova (Delinur) for translating the statements into English and to Mike Mirzayanov (MikeMirzayanov) for the great Polygon platform.

The scoring distribution will be announced later. Good luck everyone!

UPD The start time of the Round is moved on 10 minutes. Score distribution 500-1000-1500-2500-2500

UPD2 Competition completed! Thank you all! Editorial

Hello everyone!

Up to this day Codeforces showed local server time everywhere, and programmers all around the world knew exactly what 19:35 Moscow time corresponds to in their time zone. Now it will be much harder for you to make a mistake and skip another round, since you are going to see time in your time zone.

This is what a usual London programmer sees waiting for Codeforces Round #337 (Div. 2):

The problem was not that easy to implement, since many parts of the site are heavily cached, and we had to manipulate time directly in browser using JavaScript.

Thanks for your attention, good luck to all at the next round!

Hi, Codeforces!

Educational Codeforces Round 4 will take place on 25 December 2015 at 18:00 MSK for the first and second divisions. You can read about educational rounds here and here. This time a little time has passed since the previous round. Although we planned this round at Monday, we forgot to include it to schedule, so it was appeared only now. So it is the fourth and the last educational round this year.

<Maybe this paragraph will not be changed ever>

The round will be unrated for all users and it will be held with extented ACM ICPC rules. You will have two hours to solve six problems. After that you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

</Maybe this paragraph will not be changed ever>

This time the round was prepared only by me, Edvard Davtyan. Thanks a lot to MikeMirzayanov for helping to invent the problems. Also thanks in advance to Maria Belova Delinur who will check English statements, when they will be ready :-)

I think this time the problems is simpler than usually, because at first we have too hard problemset and removed the hardest problem and added very simple problem. I hope you will enjoy the problems and solve all of them!

Also I want to wish you Happy New Year!!!

Good luck and have fun!

UPD 1: The first phase is ended, hack the solutions of your opponents!

UPD 2: The editorial is ready.