Somehow it turns out that for me, each coming the New Year means more and more. This is an excellent opportunity to take stock, to breathe fresh air and to go through a kind of catharsis. This is a rare opportunity to be with the family, dress up in Santa Claus and just have fun.

Holidays give me a clear criterion that I do the right things. If during the holidays, I begin to think about it, to recall some deferred ideas, eager to implement something new. So I’m doing right things. My things. And now exactly the same as in several recent years: during New Year holidays I write code for Codeforces, trying new technology or simply I’m making minor changes in testlib. It is necessary to me: at this moment are no deadlines, do not press the obligation. Just now, at 3 am, I can not break away from being able to do something new. I would like to take a moment and realize that spun in my head the whole year.

I'm insanely happy to huge number (9144!) of registrations on Good Bye 2016. Your desire to grow, to learn new things, solve problems and invent, improve skills and compete, all this things give me strength and desire to develop the platform.

I wish you not to lose the fire in eyes, when you meet an interesting problem. I wish to continue to find pleasure in each contest or round. I wish to find, to solve more and more complicated and interesting problems. Victories and achievements! Wish you to solve all things which you didn’t solve in 2016!

Happy New Year!

But you, please read this post entirely. It is important to me. It draws the symbolic line to me and the whole Codeforces team. And, of course, below it is written about change handles gift and a colorful masquerade of ranks. Go!

Dear community!

It was a fantastic year, with great pleasure I took a role of Codeforces Coordinator. This year I learned a lot, communicated with wonderful people and realized how valuable this work is for thousands of people. I would like to thank you all for these great moments! I strongly believe that there are many cool rounds and interesting problems ahead as I'm passing this duty to Nikolay KAN Kalinin!

Please, watch my New Year's speech (Russian language, English subtitles):

P.S. Special thanks go to Maxim Zlobober Akhmedov and Oleg mingaleg Mingalev who helped me prepare this video.

Hello everybody!

On December 30 at 14:05 UTC/17:05 MSK (check your time zone here) Codeforces will host the New Year's contest Good Bye 2016. The contest is combined for both divisions, lasts 2.5 hours and contains 8 problems. Thanks to Harbour.Space and Barcelona ACM-ICPC Programming Bootcamp 2017 sponsoring the contest, winners can expect really cool prizes:

• 5 best participants (not ACM ICPC veterans) will win free participation in Hello Barcelona programming bootcamp.
• 30 best participants (not ACM ICPC veterans) will receive a 30% discount for participation in Hello Barcelona programming bootcamp.
• 100 best participants will receive t-shrits by organizers and Codeforces.

Hello Barcelona programming bootcamp in collaboration with Moscow Workshops ACM ICPC is a competitive programming training camp to be held between February 6-14, 2017 at Harbour.Space University in Barcelona. Note that lecturers and coaches are: GlebsHP, MikeMirzayanov, Endagorion, Michael, Jacob and snarknews, so the camp must be valuable. The registration is open up to January 20th, 2017.

More information can be found here: http://in.harbour.space/icpc/

I'm an author of problems. I want to thank several people. MikeMirzayanov for creating Codeforces and Polygon and for allowing me to prepare this contest. GlebsHP for his help in everything (hope to work with you again!). mareksom for testing (other testers TBA). My sister for drawing. I also want to thank the Hello Barcelona organizers for providing nice prizes for you.

I'm proud of the problem set and I think that everybody will find something interesting for themselves. I tried to keep statements shorter than usually so it may be a good idea for you to read more problems and choose one that fits you. Obviously, problems will be about the New Year and a little polar bear whom you might know. Since you will face one interactive problem, please read the Interactive Problem Guide in advance.

Don't forget to register. I wish you great fun and no frustrating bugs.

UPD1: The points drop will be adjusted to the round length. It means that for submitting e.g. at the end of the contest gives the same percent of points as in usual 2-hour rounds. Also, I remind you that there will be an interactive problem (as mentioned above).

UPD2: In 750F - Новый год и поиск корня the interactor was printing neibhours in format "k t1 ... tk" instead of "k\nt1 ... tk" (in one line instead of two lines). It's my fault and I'm sorry for the inconvenience. If you were heavily affected, please write to me or GlebsHP. And thanks for noticing/guessing, Gassa!

UPD3, WINNERS

1. Petr
2. tourist
3. rng_58
4. mnbvmar
5. Kostroma
6. Rafbill
7. Egor
8. ainta
9. al13n
10. molamola.

Congratulations!

Thanks for participating. If you want to know intended solutions, see the editorial (it isn't completely ready yet though). See you next time and have an awesome New Year!

Hello, Codeforces!

I want to test the system before Good Bye 2016, to be sure that everything works as expected.

I invite you to take part in Testing Round 13. It will start soon, on December, 29, 09:05:00 (UTC). It will be unofficial unrated round. The duration is 75 minutes.

Pretests are unusually weak to trigger more hack.

You may expect interactive problems. Hope for hacks for them.

Thank you,
MikeMirzayanov

UPD: Many thanks to all the participants. It seems the system works as expected. We are ready to host Good Bye 2016!

Traditionally, SnarkNews runs two New Year Contests.

The New Year Blitz Contest (Multiple Language Round) will start at 16:00 31.12.2016 and ends at 08:00 01.01.2017 Moscow Time. Contest consists of 13 problems. Some of those problems are based on problems, used at official or training contests in 2016. 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 01.01.2017, i.e. successful submissions at 23:50:00 31.12.2016 and at 0:10:00 01.01.2017 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.

13'th Prime New Year Contest will start at 0:00 30.12.2016 and finish at 23:59 10.01.2017 Moscow time. Traditionally, Prime New Year Contest consists of problems, which were presented at team programming contests in 2016 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. Registration is open till the end of the contest.

Hello everyone,

ACM-ICPC ECNA 2016 contest finished 2 months ago. 3 teams advanced to the 2017 World Finals in South Dakota, including the team from University of Waterloo:

Waterloo Royal Blue: FatalEagle,zxqfl,y0105w49

You can learn more about them from this ICPC News Facebook post. I am one of the coaches and I look forward to meeting everyone in South Dakota next May. Good luck to Royal Blue and all other teams at Finals. We will try not to place (lucky/unlucky)? 13th for 3 straight world finals!

I have added the contest to Gym: 2016-2017 ACM-ICPC East Central North America Regional Contest (ECNA 2016). Note that there are 3 clarifications in the announcements.

Enjoy.

Hello everyone

On Monday, December 19 at 19:35 MSK held Codeforces Round # 388 for participants from the Div.2. Participants from the Div.1 may participate out of the competition.

This round was prepared by Denis pitfall Bezrukov, Alexey dalex Dergunov, Vyacheslav Slamur Muravev, Egor Petruchcho Ponomarev, Pavel craus Semushin и Andrey Shlakoblock Gaidel.

For me and Slamur and Petruchcho this will be the first round. We hope that everyone will find interesting problems.

Great thanks to Gleb GlebsHP Evstropov for his help with the contest preparation and Mike MikeMirzayanov Mirzayanov for the Codeforces and Polygon systems.

UPD: You will be offered 5 problems and 2 hours for solving them.
Scoring: 500-1000-1500-2000-2500

Congratulations to the winners!

Div.2:

1. just29
2. tnbt
3. el_smurfo
4. SimB4
5. skydog

Div.1:

1. I_love_Tanya_Romanova
2. W4yneb0t
3. enot110
4. vintage_Vlad_Makeev
5. Um_nik

UPD: Editorial available here

Hello, Codeforces! It's me again=)

I'd like to invite you to Codeforces Round #387 (Div. 2). It'll be held on Monday, December 19 at 05:05 MSK and Div. 1 participants can join out of competition.

This round is held on the tasks of the second day of the municipal stage All-Russian Olympiad of Informatics 2016/2017 year in city Saratov. They were prepared by Olympiad center of programmers of Saratov SU.

Great thanks to Nikolay Kalinin (KAN) for helping me preparing the contest, to Tatiana Semenova (Tatiana_S) for translating the statements into English, to Mike Mirzayanov (MikeMirzayanov) for the great Codeforces and Polygon platform and to Vladimir Petrov (vovuh), Alexey Ripinen (Perforator), Mikhail Levshunov (Levshunovma), Mikhail Piklyaev (awoo), Aleksey Slutskiy (pyloolex), Ivan Androsov (BledDest), Oleg Smirnov (Oleg_Smirnov) and Roman Kireev (RoKi) for writing solutions and editorials.

You will be given six problems and two hours to solve them. The scoring distribution will be announced later. Good luck everyone!

UPD The scoring distribution 500-1000-1500-2000-2000-2500

UPD2 Editorial

UPD3 Congratulations to the winners!

1. 248926

2. vigoss18

3. haleyk100198

4. ouch__casquinha

5. peijinz

Hello, Codeforces!

I'd like to invite you to Codeforces Round #386 (Div. 2). It'll be held on Sunday, December 18 at 13:35 MSK and as usual Div. 1 participants can join out of competition. Note that round starts in the unusual time!

This round is held on the tasks of the municipal stage All-Russian Olympiad of Informatics 2016/2017 year in city Saratov. They were prepared by Olympiad center of programmers of Saratov SU.

Great thanks to Nikolay Kalinin (KAN) for helping me preparing the contest, to Tatiana Semenova (Tatiana_S) for translating the statements into English, to Mike Mirzayanov (MikeMirzayanov) for the great Codeforces and Polygon platform and to Vladimir Petrov (vovuh), Alexey Ripinen (Perforator), Mikhail Levshunov (Levshunovma), Mikhail Piklyaev (awoo), Aleksey Slutskiy (pyloolex), Ivan Androsov (BledDest), Oleg Smirnov (Oleg_Smirnov) and Roman Kireev (RoKi) for writing solutions and editorials.

It will be a little unusual round — you will be given seven problems and two and half hours to solve them. The scoring distribution will be 500-1000-1500-2000-2500-3000-3000. Good luck everyone!

UPD Editorial

UPD2 Congratulations to the winners!

1. IHaveShort

2. tqyaaaaaaaang

3. UmaThurman

4. Moiezen

5. FIKS_samurai