By amirali1374, 9 years ago, In English

Hi all!
Unknown Language Round #3 is going to take place on 30th of July. (This very Saturday -- Friday for some parts of the world)
This is the third contest of its type. The rules are easy (and fun):

  1.     Scoring is similar to that of ACM-ICPC.
  2.     The contest is not rated.
  3.     You can submit your code using only one language. This language is a secret and will be announced only when the contest begins! (We'll expect lots of coding bugs and syntax mistakes!)

This is the 100th contest on Codeforces. Congratulations to Mike Mirzayanov for developing a system that grows so fast!

There will be 10 problems overall. The tasks concentrate mainly on coding abilities rather than problem-solving and algorithmic techniques. Tasks are made by Mike Mirzayanov, Kiana Gholampoor, Soroush Farrokhnia , Amir Goharshady and Me (Amirali Mohammadzade).

We're grateful to Artem Rakhov for helping us to prepare the tasks, Maria Belova for translation, Zahra Rohanifar for testing one of the tasks and Hossein Boomari for teaching us to code!

The contest is dedicated to Mike Mirzayanov and Artem Rakhov for their great job at Codeforces and for helping us all improve our coding abilities.

UPD: The contest is over.Only 6 people solved problem J. Congratulations to Peter50216 from Taiwan for winning the contest and to the following 5 people for solving all the taks:

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Announcement of Unknown Language Round #3
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By MikeMirzayanov, 9 years ago, translation, In English
Codeforces will undergo scheduled system maintenance between July 25th and July 27th. On these days you may notice some problems in the Codeforces website or in the Codeforces judging system. If you encounter a problem, please wait a few minutes and try again. Thank you for your patience.

UPD: Work is finished, thank you all for your patience.
UPD 2: It appeared side-effect: TeX formulas, which are rendered in the images now looks supercontrast. I'll fix it soon.

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By goryinyich, 9 years ago, translation, In English
Hi there!

Me - Sergey Vedernikov - is the author of today's CF beta round.

During the round you'll assist far away kingdom citizens in solving everyday problems, and sometimes - just to fight for your survival.
This round is "red" =), therefore the problems should not appear too difficult, and you should get pleasure from solving them.
To those who know Russian language I recommend to read problem statements in Russian. Not because of the quality of translation - English just poorly communicates Russian folklore language style.

Finally I want to thank Artem Rakhov for invaluable help during the round preparation, Maria Belova for the qualitative translation of the problems, Mikhail Mirzayanov for excellent CF system and all participants for not leaving this event without your attention.

More AC verdicts and high rating to all of you! gl & hf

UPD: Unfortunately, problem B (div. 1) / D (div. 2) appeared to be more difficult, and author's solution appeared wrong. The round will be unrated. I apologise for this to all participants.

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By Michael, 9 years ago, translation, In English

Congratulations to Petr Mitrichev (Petr), the Yandex.Algorithm 2011 Champion!

Congratulations also to Dmitry Dzhulgakov (dzhulgakov), Makoto Soejima (rng_58), Ivan Metelsky (ivan.metelsky), Alexey Levin (levlam) and Gennady Korotkevitch (tourist) who placed 2, 3, 4, 5 and 6 respectively! They solved as many problems as the champion. Full results are available here

Problems turned out to be really difficult: nobody managed to solve more than 3 problems during the 2 hours of competition. Problem A was considered much simpler than all others by the contest authors, but less than half of participants could solve it, and even the champion lacked 30 seconds to fix the last bug. Only one coder could solve problem E: Xhark from Korea.

Problem E was suggested by Ilya Kornakov (ilyakor) who is also a developer in my group at Yandex :) Problem A about domino and a guy named Gena was powered by Ivan Popelyshev (ivan.popelyshev). Problem B — Stanislav Pak, C — Denis Yarets. All three are also our employees. Problem D was suggested by Artem Ripatti. My problem was rejected at the last minute, so it will wait for you at the Petrozavodsk training camp :)

Thanks to all finalists, authors, participants out of competition, contest organizers, MIPT for the accomodations and the main sponsor — Yandex.

Good luck to everybody who competes in the OpenCup onsite today!

A few more photos from the competition:

Petr and our foreign guests rng_58, wata and dolphinigle
ivan.metelsky, MikeMirzayanov and pieguy

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By Michael, 9 years ago, translation, In English

Hi everybody!

Yandex.Algorithm finalists were gathering in Dolgoprudny... Everybody in their own unique way :)

dzhulgakov, pieguy, levlam and Progger turned out to be the most organized and arrived at the start of the Summer School. They've already socialized with other participants and began solving and competing in the practical bioinformatics problem using a distributed Hadoop cluster accessible for all school participants — good for them! Two Japanese buddies rng_58 and wata landed at Sheremetyevo airport on July 13 at 17.55, and an hour later they were already receiving their badges from me. Their fellow-countryman LayCurse mixed up the dates and took the tickets for the same flight but for July 14 :) tourist with his father came in the morning on July 14th, and dolphinigle landed yesterday late in the evening and told me I was the first man in Russia he met who spoke English :) ivan.metelsky "burst" into the room of the School organizers sleeping after yesterday's party at 8 AM; he got there himself without any instructions :) e-maxx arrived at Moscow by train at 10.38 in the morning and made his way directly to the competition with our other friends from Saratov - with some adventures on the way: the electric trains to Dolgoprudny have a break from 11.10 till 13.40. ktuan decided last minute that he won't spend his last univercity vacation for the finals, and Burunduk1 seems to have been too busy with teaching high school students and didn't answer my e-mails and phone calls (tut-tut, Sergey!) — I wonder whether he will be coming last minute. Petr will drive here from Moscow just before lunch. My intern zeliboba studies at MIPT and lives in the same building where all the other participants of the Summer School, so he'll probably come to the contest floor last :)

Everybody can register and participate in the round as usual. Those who don't participate in the onsite round will be out of competition, but the round is rated for everybody in Div-1.

I remind you that the contest time is unusual today: we will start at 16.00 The problems are harder than usual in Div-1 today — looking forward to a bitter struggle!

Update: full results

A few photos from the School's life starring our finalists Progger и pieguy:

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By witua, 9 years ago, translation, In English
Hello everyone!

Welcome to Codeforces Beta Round #77. I am Vitaliy Gerasimov (witua) and I am an author of today's problems. Thanks to Artem Rakhov (RAD) and Pavel Kuznetsov ( for the help and advices in preparing of the rounds, Maria Belova (Delinur) for the problem translation and Codeforces (CF) for being.

Good luck!

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By dalex, 9 years ago, In English

Hi all!

My name is Alexey Dergunov, and I'm glad to present you the first "violet" Codeforces round. I hope the problems will not seem so "violet" to you :)

Many thanks to following people who helped me a lot with contest preparation:

Good luck!

UPD. Contest is over, and we know the winners!

Division 1:
Division 2:

UPD 2. Analysis: (English version is not full yet...)

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By Connector, 9 years ago, translation, In English

Hello everyone.

Today I am an author of the contest. This round is for both divisions. There will be five problems in each division. This is my second round on the Codeforces. The actors in this contest will be walruses again =)

I want to thank Codeforces and Alias for helping me to prepare the round.

Good luck!


Points for problems in div1: 500-1000-1500-2500-2500

Points for problems in div2: 500-1000-1500-2000-2500


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By Ripatti, 9 years ago, translation, In English

Hello everyone!

I am an author of problems of today round. This round is for both divisions. There will be 7 problems, the first 5 of them are for the second division and the last 5 are for the first one.

About points of problems. Today they are nonstandard:
for div2: 500-1000-1500-2000-2000
for div1: 500-1000-1000-1500-2500
Be careful.

RAD helped me for preparing the round. Delinur translated statements into English.

Good luck ans have fun.

 winners of the first division
1. peter50216
2. tourist
3. ACRush

winners of the second division
1. iamcs1983
2. zyx3d
3. seanwupi


Unfortunately, in author's solution of priblem E some bug was found. We thanks participant LinesPrower for detection of it. Author's solution was updated and all solutions were rejudjed. Ratings will be recalculated for all participants excluding Egor and Jacob. We apologize for this incident.

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By MikeMirzayanov, 9 years ago, translation, In English

The first information letter

General information

From 1nd to 11th August 2011 Saratov State University runs an international student summer school in computer programming. Teams of three people and individual participants are invited to take part in it.

The school will take place in a picturesque place at one of Saratov resort centers on the Volga bank. The participants will be provided comfortable rooms for 2-4 people and meals three times a day. The resort center owns a beach and sport grounds.

It will be 10 training days. The school includes lectures by Saratov state university coaches, joint trainings, problems tutorials and topical workshops. The curriculum is designed for younger university students who aspire to achieve high results at programming competitions. Official language — Russian.

The fees are 16000 RUR (~ 570 USD) for a person. Moreover, each team or an individual participant should bring a laptop with the support of WI-FI.

All interested participants and teams should register at till 20th June 2011. Don't postpone the registration, as the number of participants we can take is limited.

You can get additional information by e-mail mirzayanovmr[symbol-at] As since the official language of the school is Russian, the registration requires knowledge of Russian. Also it is recommended to view this page in Russian.

About Saratov State University

Saratov State University, regularly achieves significant advances in programming competitions. The following are the main achievements of the university in international competitions:

  • 2002 ACM-ICPC World Finals silver medals, Europian Champions
  • 2003 ACM-ICPC World Finals silver medals
  • 2006 ACM-ICPC World Finals golden medals, Europian Champions, World Champions
  • 2007 ACM-ICPC World Finals silver medals
  • 2009 ACM-ICPC World Finals golden medals
  • 2010 ACM-ICPC World Finals silver medals
  • 2011 ACM-ICPC World Finals silver medals
Mike Mirzayanov,
Saratov State University

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