Hello Codeforces!

Soon you are lucky to participate in Codeforces Round #302, and I am writer of this contest.

I want to thank Max Akhmedov (Zlobober), Alexander Ignatyev (aiMR), Danil Sagunov (danilka.pro) for help with preparation of this round, Maria Belova (Delinur) for translation of statements and Mike Mirzayanov (MikeMirzayanov) for marvelous Codeforces and Polygon systems.

Scoring will be next:

1. Div1: 500 — 1000 — 1750 — 1750 — 2500
2. Div2: 500 — 1000 — 1500 — 2000 — 2750

Contest finished, congratulations to winners:

Div1:

1. Petr
2. qwerty787788
3. -XraY-
4. kraskevich
5. Merkurev

Div2:

1. nka55
2. never_retired_phoenix
3. lowsfish

Editorial

This Sunday, May 3-rd, 19:00 Moscow Time there will be Round 3 of VK Cup 2015 Championship!

As in Round 2, there will also be an online mirror that is rated round available only for Div1-contestants. There will be 6 task in random order and a smooth dynamic scoring system.

Round was brought to you by Codeforces team, VK team and yeputons. As usual, we want to thank winger and AlexFetisov for a great testing help.

Top-50 participants of online mirror will get a nice VK Cup T-Shirt!

Good luck and have fun!

UPD1 The round is over! Congratulations to all contestants in top-50, you will get a nice VK Cup 2015 Championship T-Shirt soon! There will be an editorial soon, stay tuned...

UPD2 Finally, the editorial is ready!

Final scoreboard

Introduction

Arrival

History

Some photos from contest and closing ceremony

Interview with Bayan CEO Ali Ghadiri and some photos from the event will be published tomorrow

Places 10-15 received bronze medals

Top 3 receive gold medals. Silver medals for next several places: 4. Adrian Budau 5. Peyman Jabbarzade 6. Pooya Zafar. Places 7-9 also received silver medals, unfortunately I could not keep up with announcers

Nikola Djokic is third!

Ali Haghani is second. Congratulations!

And the winner is Evgenii Kapun aka eatmore

Winners will be announced shortly!

Speeches, videos and performances — all the usual things for closing ceremony.

Closing ceremony is underway. We'll know winners shortly

Scoreboard is frozen

3:01 Contest is over. Congratulations to all finalists and good job

2:32 Last half hour is upon us which mean no more updates to scoreboard. Come back tomorrow for closing ceremony and winners announcement

2:22 Eugene solved G as well. Would it be enough to clench the title?

2:15 Meanwhile Ali Haghani continues to try to solve problem H

2:05 Problem D is penultimate problem to be solved thanks to Peyman Jabbarzade. Less than an hour left in the contest, scoreboard will be frozed for the last 30 minutes

1:53 Problem G is solved as well. Only problems D and F are unsolved (though I solved them both during test run)

1:39 And finally he is successful. Meanwhile Ali Haghani tries to solve H. No luck as of yet

1:34 eatmore still debugging E — one of his asserts fails

1:22 eatmore debugging samples on E. This is also the problem I had not solved during test round (and still don't know how to solve)

1:18 No much happening near the top at the moment

1:00 One more problem is "opened" — problem C. Kudos to Ali Haghani

0:50 39 finalists solved first problems while 12 — second

0:40 During test run I solved 6 problems, but H was not one of them (I solved it within half hour afterwards though)

0:30 Top 5 solved 2 problems

0:23 A lot of correct submissions on problem A, problems B and H are also "opened"

0:10 Eryx tries to tackle first problem as well, but not successful yet

0:08 But we have our first Accepted. Congratulations to Ali

0:06 Most participants just read problem statements (there are paper ones), not yet trying to code anything

0:01 Contest is started

-0:17 Contest likely to start in 17 minutes

-?:?? Test contest is still underway

-?:?? Contest is delayed. Currently short test round is conducted. Finalists set up their equipment

-0:13 Last preparations are made. Participants waiting in the hotel lobby

-0:52 Participants had finished their breakfast and will shortly arrive to contest area

-3:00 Finals are supposed to start in 3 hours. Stay tuned

Hi all,

I was honored to open the fourth hundred of Codeforces Rounds. Unfornunately, neither I nor my friends couldn't invent any hard problems, so it's only a Div. 2 Round. But we'll definitely prepare a full round in the future! As always, I thank Zlobober for his help in preparing the problems, Delinur for English translations and MikeMirzayanov for the Codeforces itself.

The problems must be pretty easy for Div. 1 guys, so let's start a challenge: reds should solve everything in 30 minutes, yellows — in 1 hour, and violets — in 1 hour and a half. How many people will be able to make a success?

The score distribution will be standard. Wish you accepted solutions and successful hacks!

UPD 1. Congratulations to the winners in Div. 2:

1. PauGra
2. cuvwqe496
3. tgehr

and in Div. 1:

1. niyaznigmatul
2. I_love_Tanya_Romanova
3. dreamoon_love_AA

UPD 2. This is the editorial: /blog/entry/17643.

Hello, Codeforces!

On Sunday, April 26th at 19:00 MSK the 300'th regular Codeforces Round will take place.

I would like to congratulate all Codeforces members and administration on this remarkable milestone. The platform has grown hugely in size and quality since its foundation, has hosted lots of exciting competitions, and has been providing the opportunity to everyone to hone their problem solving and algorithmic mastery. For this we thank the Codeforces platform creator MikeMirzayanov and all the Codeforces crew. Keep up the incredible job, guys!

That being said, I'm excited to announce that the problems on the jubilee three-hundredth Codeforces Round will be set by me, Mikhail Tikhomirov (Endagorion). You may remember the past rounds with my problems: #99, #109, #265, #283, and (in part) #295. I thank the Codeforces problems coordinator Max Akhmedov (Zlobober) for helping me in preparing this round, and Maria Belova Delinur for translating the statements in English. Also, special gratitude to Vladislav Isenbaev (winger), Alex Fetisov (AlexFetisov) and Pavel Kunyavskiy (PavelKunyavskiy) for testing the problemset and help with preparation.

This round will be shared for both divisions and will last two hours and a half (as you can see at the Contests page). The round will feature several ( ≥ 6) problems, varying in difficulty and topics involved. I hope that everyone will find an interesting and satisfying problem just for themselves! The scoring will be announced later.

To add up to the excitement, there are 30 exclusive Codeforces T-shirts to compete for in this round! The top 15 participants will get their T-shirts right away; another 15 will be randomly distributed among those who place in the top 300. Even if you think your chances on being the very best are weak, there are still good odds you will get a treat! =)

That's it. Mark your calendars and come back to compete for the prizes and for the fun!

UPD: there will be 8 problems. The scoring is standard (i.e. not dynamic): 500-1000-1500-1500-2000-2500-3000-3000.

UPD2. In order to choose people getting T-Shirts we will use the following python3.4 code that you can manually run in "custom invocation" tab on Codeforces. It uses an integer as a seed for random generator, this integer should be equal to the last submission number that happened during the contest.

import random
seed = int(input())
rnd = random.Random(seed)
# all contestants except top-15
contestants = list(range(16, 301))
rnd.shuffle(contestants)
tshirts = list(range(1, 16)) + contestants[:15]
for x in sorted(tshirts):
    print(x)

UPD3: Thanks for participating!

The winners are:

1. bmerry
2. Egor
3. Petr
4. rng_58
5. scott_wu
6. jqdai0815
7. eatmore
8. atetubou
9. qwerty787788
10. niyaznigmatul

The list of places getting the T-shirts are 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 40 46 67 75 80 102 103 144 152 161 169 198 233 243 269. The lucky participants are as follows: bmerry, Egor, Petr, rng_58, scott_wu, jqdai0815, eatmore, atetubou, qwerty787788, niyaznigmatul, gs12117, W4yneb0t, JoeyWheeler, zxqfl, yeputons, kcm1700 & HYPERHYPERHYPERCUBELOVER (sharing the 40-th place, so both get a T-shirt), piob, Leo_Yu, matrix & Nerevar (sharing the 75-th place), Haghani, ACube, DemiGuo, etal, Emarci15, hlwt, Salvare001, dzy97, FatalEagle, gchebanov & Jimanbanashi (sharing the 243-rd place), and Solaris (please let me know about any mistakes). Congratulations!

UPD4: At long last, the editorial is up! Enjoy, and sorry for the waiting.

April 18, 18:00 (UTC) the second Wild-card round of VK Cup 2015 will take place.

Participants are invited to achieve progress in solving an unusual problem. VK Cup teams which were advanced to the Round 2 (and didn't advance to the Round 3) will take part in VK Cup 2015 - Wild Card Round 2 officially. In addition, this round will be open to the public for unofficial participation for everybody. Registration will be open for the whole round duration.

The round will be one week long. After the end latest submission (with positive score) of each participant will be judged on system tests.

Good luck!

UPD.: System testing is done. Final tests are available by link: http://assets.codeforces.com/files/vkcup-2015-wildcard-2-tests.2.zip

You can appeal on tests and their answers until April, 28th, 23:59:59. After that we will finalize the results. After finalizing all found bugs will not affect the final standings.

This Friday, April 17th, 19:00 there will be Round 2 of VK Cup 2015! For all unofficial participants there will be an online mirror that is a usual rated div1-round. Any div1 contestant that does not participate in official Round 2 is able to compete in this mirror.

Round consists of 6 problems that are shuffled randomly. There will be a smooth dynamic scoring system.

Round is brought to you by Codeforces team, VK team and user Errichto, that offered his important help as a part of his donation for "Codeforces 5 years campaign". Significant testing effort was made by user winger.

Good luck and have fun!

UPD: Thanks everybody for participating! Editorial has just appeared. See you on Wild-card Round 2 and mirror of Round 3!