Important Update: Our friends have noticed that the upcoming round collides with their contest and also weekend is full of many another contests, so the round is now moved to Monday, 29 August 2016 15:05 MSK. We are sorry for the inconvenience caused and hope that you'll understand us.

Hi everyone!

Codeforces Round #369 (Div. 2) will take place on 27 August 2016 at 16:05 MSK. As usual, Div.1 participants can join out of competition.

I would like to thank danilka.pro for helping me with the preparation of the round, MikeMirzayanov for the amazing Codeforces and Polygon platforms and also Phyto for testing the problems.

I am the author of all the problems, and danilka.pro also helped making one of the problems harder. This is my first round on Codeforces! Hope everyone will enjoy the problems and find them interesting. It is advisable to read all the problems ;)

In this round, you will help ZS the Coder and Chris the Baboon while they are on an adventure in Udayland. Can you help them solve their problems? :)

Good luck, have fun, and wish everyone many Accepted Solutions. :)

UPD : Also thanks to IlyaLos and HellKitsune for testing the problems too.

UPD 2 : There will be 5 problems and the scoring is standard : 500-1000-1500-2000-2500.

UPD 3 : Editorial

UPD 4 :

Congratulations to the winners :

Div. 1 winners :

1. matthew99

2. uwi

3. Egor

4. Um_nik

5. kmjp

Div. 2 Winners :

1. zhabo

2. ysy_ioi_pengbei

3. YangJunzhao

4. lych_cys

5. Zharaskhan

Hi, Codeforces!

AIM Tech Codeforces Round 3 will take place on August 24, at 19:35 MSK.

The round is prepared by AIM Tech employees: Kostroma, riadwaw, yarrr, ValenKof, Edvard, bobrdobr, malcolm, NVAL, nmakeenkov, agul, Extr and zeliboba. Round will take place during Petrozavodsk Summer Camp, which is sponsored by our company.

We made our problems a little easier than at AIM Tech Round 1 and AIM Tech Round 2 but we promise they won’t be less interesting. Scoring system will be static.

Thanks to Mike Mirzayanov(MikeMirzayanov) for brilliant platforms Polygon and Codeforces and problem coordinator Gleb Evstropov (GlebsHP). Many thanks to AlexFetisov and winger for round testing!

Our company specialises in proprietary trading, the key concepts in our work are big data, low latency and high frequency. Our team mainly consists of graduates from the MSU Faculty of Mechanics and Mathematics and Moscow Institute of Physics and Technology (MIPT).

We wish you good luck and high frequency rating!

Scoring in both divisions 500-1000-1500-2000-2500

Editorial

Hello, Codeforces!

Educational Codeforces Round 16 will take place on 22 August 2016 at 17:00 MSK for the first and the second divisions.

It will be the last educational round prepared by me. As I earlier said I started to work at the great team of AIM Tech and now have less time to prepare a rounds. To leave the rounds interesting and qualitative another guy will continue to prepare them.

The problemset was partially suggested by Codeforces users. The problem C was suggested by user Resul Hangeldiyev Resul. The problem E is the next problem suggested by Zi Song Yeoh zscoder. The problem F was suggested Alexandr Kulkov adamant. Other problems was suggested by me (they are standard, but it is important to be able to solve them).

All the problems was prepared by me (Edvard Davtyan). Thanks to Tatiana Semyonova Tatiana_S for checking the English statements. Thanks a lot to Ivan Popovich NVAL for testing the problems A-E and Alexandr Kulkov adamant for testing the problem F.

I hope you will enjoy the problems! I think the problemset is little bit more difficult than usual, but I'm sure that it will not stop you :-)

Good luck and have fun!

UPD 1: The testing on hacks is completed. Thank you for participation!

UPD 2: The editorial is ready.

Hello everybody!

Codeforces Round #368 (Div.2) takes place on August 20th. As usual Div.1 participants can join out of competition.

I am the author of all problems.

I want to thank danilka.pro and GlebsHP for helping me prepare this contest, vovuh for testing it, Roms for statement reading and MikeMirzayanov for platforms of Codeforces and Polygon.

I advise you read all problems, hope, you will enjoy them :)

Good luck and have fun!

UPD1: 500-1000-1500-2000-2500

UPD2: tutorial

Hi everyone!

Codeforces Round #367 (Div.2) takes place on 11th of August at 19:35 MSK. As usual, Div.1 participants can join out of competition.

This is my first round on Codeforces! I advise you to read all the problems. Hope everyone will find something interesting.

I'd like to thank GlebsHP for helping me in preparing this round, Yury_Bandarchuk and IvanVan for testing tasks. Of course, many thanks to MikeMirzayanov for great Codeforces and Polygon platforms.

UPD: Scoring is 500-1000-1500-2000-2500

UPD: Editorial

UPD: The contest is over. Congratulations to the winners!

Div.1 winners:

1.anta

2.W4yneb0t

3.sugim48

4.uwi

5.Kmcode

Div.2 winners:

1.jiangzixiao

2.Shining

3.BurningHuie

4.AwD

5.stjepanp

Hello ladies and gentlemen.

I'm honored to announce you that Codeforces Round #366(or should I say, IOI 2016 opening CF contest) is gonna take place on August 7th and I'm the writer. Please note that the timing is unusual.

As usual, there are 5 problems in each division and duration is 2 hours.

I want to thank LiTi for testing this round, GlebsHP for helping me prepare it and MikeMirzayanov for legendary and unique platforms of Polygon and CF.

The main characters of this round are The Avengers!

I wish you all Accepted solutions and Successful hacks.

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 participant in each division (only with handle present in this list) will be rewarded with Persian souvenirs in Kazan.

UPD: Totally unrelated, but since the previous IOI group in telegram no longer exists, here's a new group!

UPD: Scoring is 500 — 1250 — 1250 — 2000 — 2500 in Div.1 and 500 — 1000 — 1500 — 2250 — 2250 in Div.2

UPD: I'm really sorry about the difficulty. System test is about to begin.

UPD: Editorial is out.

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

Div.1 winners are:

1. kcm1700
2. WuHongxun
3. dotorya
4. lawrenceli
5. W4yneb0t
6. Swistakk
7. KADR
8. fqw

Div.2 winners are:

1. korla.march
2. dev.plvlml
3. dantrag
4. ODT
5. ntopia
6. vokeal
7. pyrexshorts
8. _index

Souvenir winners are lawrenceli from team USA and eXeP from team Finland (If that's not true write me in private).

Hi everyone!

Codeforces Round #365 (Div.2) takes place today on 4th of August at 18:05 MSK. As usual Div.1 participants can join out of competition.

I am the author of all the problems, and this is my first round on Codeforces. I advise you to read all the problems, hope you will enjoy them :)

I'd like to thank GlebsHP and danilka.pro for helping me in preparing problems, MikeMirzayanov for the great Codeforces and Polygon platforms and IlyaLos for some useful adviсe.

In this round you will meet Mishka, a little polar bear. She is still young, that's why she may have some problems in finding answers for difficult questions. Will you help her to cope with some of them? :)

UPD. 5 problems, 2 hours to solve them and scoring distribution: 500 — 1000 — 1750 — 2000 — 2250

UPD. We apologize for the inconvenience. All solutions will be judged soon.

UPD. Round is unrated.

UPD. The contest is over. Congratulation to the winners!

Div1: 1. uwi 2. kmjp 3. savinov 4. BigBag 5. KrK

Div2: 1. meteor 2. TmEnd 3. chenjiamin 4. vokeal 5. Denisson

Editorial will be published in the nearest time.

UPD. Editorial

Hello, Codeforces!

Educational Codeforces Round 15 will take place on 29 July 2016 at 18:00 MSK for the first and the second divisions.

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.

We with Mike MikeMirzayanov Mirzayanov decided to prepare this Round, because Edvard Edvard Davtyan is very busy at his new job. Good luck and have fun!

UPD Competition completed! Thank you all! Editorial