By MikeMirzayanov, 8 years ago, translation, In English

Today, June 2, 2016 year, there was a technical failure, which I will remember for a long time. Several factors led to a serious malfunction of the Polygon system.

The fact that in the middle of May Polygon was transferred to servers located in Mail.Ru data centers. To transfer with almost no downtime (Polygon has a lot of data, about a terabyte) lsyncd utility has been used, which quickly pushed the file changes from the old server to the new one.

Today there was a reboot of the old server, which forced the unplanned start of lsyncd daemon. As a result it did the synchronization of data from the old server to the new again. So, data stored in the file system have been rolled back to the transfer time (May 13). The most unlucky fast that, unlike the old server where the backups system was set up well and reliable, on the new server, I quickly managed to set up only replication using the same lsyncd, which does not help in the incident of files deletion (as it forces the removals on the replica). Obviously, RAID-1 disks didn't save the data.

As a result, all file changes in the Polygon system made in three-week period were lost. Some information (statements, etc) is stored in the database, so accessible.

This night I urgently implemented the special link "Scraps" to download the archive with the available data. If a problem has been used in the Codeforces infrastructure, the packages remain in its cache of the judging system, they are available in archive.

I feel lousy realizing that my lack of attention to detail has led to such consequences. I distinctly remember the black day of Codeforces — and as a result many things have been much revised (everywhere mirrored disk arrays, replicas and backups). Unfortunately, this time after moving to new hardware I did not return all scripts and here is the result. Problem writers please accept my deepest apologies for my mistake.

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By Wild_Hamster, history, 8 years ago, translation, In English

Greetings to the Codeforces community!

Regular Codeforces round #355 for participants from the second division will take place on 1 June, 19:35 MSK. Participants from the first division are able to participate out of the contest.

It is my third round on Codeforces. Hope you will enjoy this round.

I want to thank Gleb Evstropov (GlebsHP) for help with preparation of this round and Mike Mirzayanov (MikeMirzayanov) for great Codeforces and Polygon systems.

Participants will be given five problems and two hours to solve these problems.

UPD Score distribution: 500-1000-1500-2250-2250

UPD Editorial is here

UPD Congratulations to the winners!

Div. 2

  1. fake_fake

  2. __Wind

  3. Mamedov

  4. dianaasau

  5. Sorry_Daikon

Div. 1

  1. Um_nik

  2. TimonKnigge

  3. vintage_Vlad_Makeev

  4. anta

  5. kmjp

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By RussianCodeCup, history, 8 years ago, translation, In English

Hi all!

The second qualification round of Russian Code Cup 2016 will take place on Sunday, May 29, 2016, at 12-00! We invite everyone who has not qualified yet to take part. Those who would not qualify in the second round are invited to take part in the third round on June 5. Good luck to everyone and see you at the round, don't forget to register for the championship at http://russiancodecup.ru if you haven't done so already.

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By fcspartakm, history, 8 years ago, translation, In English

Hello, Codeforces!

I'd like to invite you to Codeforces Round #354 (Div. 2). It'll be held on Wednesday, May 25 at 18:05 MSK (Moscow time) and Div. 1 participants can join out of competition. As usual round starts in the unusual time!!!

Me an Grigory AGrigorii Akhremenko prepared the tasks for this Round. It is the debut for Grigory as the problemsetter.

Great thanks to Gleb GlebsHP Evstropov for helping us preparing the contest, to Mike MikeMirzayanov Mirzayanov for the great Polygon platform and for Ilya IlyaLos Los and for Artur ikar Svechnikov for writing solutions.

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

UPD Score distribution 500-1000-1500-2250-2250

UPD2 Editorial

UPD3 Congratulations to the winners

  1. Thomas66

  2. super_wormy

  3. Valkata.a.k.a.TheHacker

  4. tcchung

  5. Krktv

UPD4 See you soon!=)

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By Chmel_Tolstiy, 8 years ago, translation, In English

Yesterday ACM ICPC World Finals finished. We congratulate all winners, medalists and special prize winners!

We want to remind you that tomorrow, May 21, at 00:00 (UTC+3) the qualification round of Yandex.Algorithm will start. For participation in qualifications you should register and start a virtual contest at any time prior to May 23 (UTC+3).

As usual 6 problems of varying difficulty will be provided at Yandex.Algorithm rounds. In order to qualify for the elimination stage rounds and compete for a trip to the finals in Minsk and other prizes you should solve at least one problem.

Also Yandex.Algorithm offers students to participate in the internship track. For more information see the rules of the championship.

Good luck! See you at Yandex.Algorithm!

P.S. The qualification round has started. Problems prepared by Romka, Ixanezis and Chmel_Tolstiy.

EDIT. Analysis has been posted.

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By MikeMirzayanov, history, 8 years ago, translation, In English

ACM-ICPC World Finals 2016 will take place on May, 19, 03:00 (UTC). It is one of the most important events in programming competitions life.

More than 40000 contestants from 2736 universitites from 102 countries had competed in regional competitions. 128 teams had advanced to the World Finals, which are held this year in Phuket, Thailand. Soon we will know which university takes home the most prestigious title in programming — the tile of the World Champion of ACM ICPC!

Useful links:

I wish the teams good luck and many baloons!

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By MikeMirzayanov, 8 years ago, translation, In English

The Finals of ACM-ICPC 2016 in full swing! Teams and organizers gathered in Thailand. The weather is fine — heavy showers at nights, hot days. The rainy season is in action. Here it is about two a.m. now, but as I absolutely can not sleep, I decided to share my impressions and photos from the first two days of the main event.

This year, the teams' resettlement delivers certain inconveniences — teams and coaches live in the same hotel, and all the other members of the delegation live in another. The first hotel (Le Meridien), is probably a bit better — own way out to the ocean and pool make everybody to envy those who lives in the Mövenpick (yes, like an ice cream).



Le Meridien, photo from the official hotel website

Buses ply between hotels, you need an hour to go. A bit uncomfortable that the buses do not run every day, or at least not always, only as scheduled.

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By komendart, history, 8 years ago, translation, In English

Hello, everyone!

Codeforces Round #353 (Div. 2) will take place tomorrow on the 16th of May at 19:35 MSK. I tried to make interesting problems, hope you enjoy them.

I'd like to thank GlebsHP for his help in preparing problems and MikeMirzayanov for Codeforces and Polygon.

Good luck!

UPD Scoring 500-1000-1500-2000-2500

UPD Editorial

UPD Congratulations to winners!

Div. 2

  1. mimirrow

  2. Salvare008

  3. orzchimo

  4. student_hh

  5. Pain_Konan

Div. 1

  1. ksun48

  2. sugim48

  3. KrK

  4. cgy4ever

  5. nfssdq

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By muratt, 8 years ago, In English

Hello Codeforces!

I am glad to invite you all to participate in regular Codeforces Round #352 that will take place on 11 May, 19:35 MSK. This will be my first round, so I hope that it will be interesting for you guys. There will be 5 problems for each division, and contest will last 2 hours.

Round wouldn't take place without the help of GlebsHP, I am very thankful for his great help. I also want to thank to Zlobober, winger, AlexFetisov, ikbal and ykaya for testing problems, to hasanb for inspiring me in a problem. I got great help and wise advices from all of them so this is their round too as much as mine. Of course I want to thank Mike and all others who puts his effort into Codeforces and Polygon systems. I don't know what we would do without this great platform.

UPD1: Score distribution:

Div. 2: 500-1000-1500-2000-2500

Div. 1: 500-1000-1500-2000-3000

UPD2: I will post editorial as soon as possible, thank you for your patience. Congratulations to winners!

Div.1 winners:

1-subscriber

2-W4yneb0t

3-jcvb

4-Merkurev

5--XraY-

Div.2 winners:

1-the_arr_of_war

2-Shavkat_Aminov

3-Lightning34

4-I_Love_Ginger

5-tjandra

UPD3: Editorial is now available.

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