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

UPD2: Tomorrow (July 31st, Sunday) at UTC 10:00 there will be an online mirror of Yandex.Algorithm final round.

Enter contest.

Everybody are invited to participate! You may discuss problems in comments after the contest ends.

UPD3: The online mirror has finished! Congratulations to ImBarD aka Vercingetorix for taking the first place.

Problem editorial

===================================================

Hi everybody!

We're glad to remind you that tomorrow, July 29th, at 9:00 AM UTC there will be the Final Round of Yandex.Algorithm 2016 in Minsk. List of finalists and elimination stage results are available on Yandex.Algorithm website.

You can watch follow the news on final round at Yandex.Algorithm website. Want to solve final round problems? On Sunday, July 31st, at 10:00 AM UTC there will be a mirror of the competition. Everybody can participate in it, solve the same problems as finalists and try his or her best on the finals' problemset.

The final round has been prepared by authors of previous stages of Yandex.Algorithm: Endagorion, Romka, Chmel_Tolstiy, GlebsHP, snarknews, Gassa and your humble servant. We believe that problems are various and interesting.

In this post after the cut I'll write some comments about what happens in the contest trying not to spoil any important details (we don't want to provde help or to ruin contest for any of the participants, isn't it?).

See you tomorrow!

UPD:

Congratulations to the winners!

1. Egor winning 300 thousands of rubles.
2. W4yneb0t winning 150 thousands of rubles.
3. rng_58 winning 90 thousands of rubles.

Final results are available here. The competition is finished, everybody are invited to participate an online mirror on Sunday!

Hello everybody!

Today the second regular rated round based on problems of VK Cup 2016 Final Round will take place. Of course, we have created some more easy problems to fulfill the requirements of different skill levels and make the contest interesting for everyone.

The commentators of the previous announcement pointed out that I forgot to thank MikeMirzayanov for making Codeforces and Polygon so awesome. I was wrong, Mike, that's really cool :)

Scoring distribution will be published right before the start of the contest. We wish you good luck and beautiful solutions!

UPD1. Scoring for div2: 500-750-1000-1500-2000-2500. Scoring for div1: 500-1000-1500-2250-3000.

UPD2. The contest is over, congratulations to winners!

Div1:

1. ainta

2. W4yneb0t

3. Petr

4. muratt

5. kcm1700

6. Vercingetorix

7. Tinsane

8. Reyna

9. aid

10. zemen

Div2:

1. MinamiKotori

2. Ancient_mage

3. WhatTheFua

4. Yanba

5. macieck9

6. OMRailgun

7. radoslav11

8. zhsh

9. skywalkert

10. abgnwl

UPD3. I sincerely apologize for the delay with problem analysis. I was out of town for a vacation. Here it is.