By MikeMirzayanov, 10 years ago, translation,

Hello!

As you have already noticed the menu will link to the results of the competition has appeared. Drum roll, fanfare, applause, and the blinding spotlight! We congratulate the winners:

• Winner is Aleksey, 33 score points!
• The second place — mrButt, 30 points
• The third place — Sanya_M, 29 points
• The fourth place — Ruslan, 25 points
• The fifth place — MaxBuzz, 24 points

Congratulations to all winners! Note that the program by Aleksey has surpassed all expectations of the jury erred solely on hard-to-recognize archives.

I'm asking all winners to send me a private message, we have something to discuss.

MikeMirzayanov

UPD: One test has been found in which the author's answer was incorrect. I've rejudged solutions, but the order of participants has not changed :)

• +25

By Alex_KPR, 10 years ago, translation,
Hi all!

Glad to see you on the Codeforces Beta Round #69. As you suspect, it's not an usual contest.

Every division has 5 problems. Some problems are in both divisions; other are meant for certain division. But from the participant's point of view there are no striking differences from other rounds.

Please notice that such an experiment is the first one, so some technical troubles and unexpected problems are possible. Please treat with understanding if it occurs.

Also: the costs of the problems in the first division are 500-1000-1500-2000-2000. In the second division the costs are classic: 500-1000-1500-2000-2500.

The round was prepared by Alex_KPRdagon and Marishka. Also and it4.kp helped very much. The statements were translated by Maria Belova. The whole process was supervised by Mike Mirzayanov.

Good luck all!
_____________________________________

_____________________________________

Top 10 participants in the first division are:
 Place Who 1 vepifanov 2 KADR 3 hos.lyric 4 Zhukov_Dmitry 5 e-maxx 6 Romka 7 ivan.popelyshev 8 Shef 9 RAVEman 10 ktuan

Top 3 participants in the second division are:
 Place Who 1 Gluk 2 nvilcins 3 piloop

Congratutations! Good luck for everybody at the next round!
_____________________________________

Editorial is here.

• +177

By Ripatti, 10 years ago, translation,
Hello everyone!

I am an author of the today problemset. It is my third contest on Codeforces and the first one for div 1.

I thanks Artem Rakhov, Maria Belova, Pavel Kuznetsov and Mike Mirzayanov for help in preparing of this round.

Happy hacking!

Winner is tourist.
Editorial.

Announcement of Codeforces Beta Round #68

• +183

By ahmed_aly, 10 years ago,
Hi everyone,

Today I'll be the author for this round, and it's my first time to be an author in Codeforces. I hope you will like the problems and find it interesting, even for Div1 coders.

I would like to say thanks for Artem Rakhov for solving and testing the problems, for Maria Belova for preparing the problem statements, and for Mike Mirzayanov for this great system.

Good luck and have fun.

Edit 1: Congratulation to the winner Chubcheg.
Edit 2: The problem editorial is here.

• +99

By KADR, 10 years ago, translation,
Hello everyone!

I woud like to announce unofficial translation of All-Ukrainian School Olympiad in Informatics, which will take place on Codeforces at Tuesday, 12th of April at 16:00 MSK. Contest will be based on problems from recently finished All-Ukrainian Olympiad in Infomatics - UOI2011. It will go according to the ACM-ICPC rules. Both teams and individuals are eligible for participation. The contest will be unrated.

We kindly request not to discuss problems from this olympiad before its ending and not to participate in this contest if you already know statement or solution of any problem from it.

The authors are: Daniel Neiter, Roman Iedemskyi, Roman Rizvanov, Ilya Porublyov and me (Iaroslav Tverdokhlib).

The PDF problem statements will be available via links:

• +69

By ashmelev, 10 years ago, translation,
Good afternoon!

Authors of the today's contest are Evgeny Lazarev (Nizhny Novgorod STU) and me (Alexey Shmelev, Nizhny Novgorod SU)

Today you will help a boy Vasya find himself in the world of computer games.

Please note, that the round will be held in unusual format - 6 problems with costs 500, 1000, 1000, 1500, 1500 and 2000 points.

### The round duration is increased to 2 hours and 30 minutes.

We say thanks to Marya Belova for statements translations, Artem Rakhov and Alexander Kouprin for help in contest preparation, writing alternative solutions and preparing of intricate tests.

Good luck and successful submission!

UPD: We apologize for inaccuracy in problem E and incorrect answers to several contestant clarifications.

Announcement of Codeforces Beta Round #66

• +61

By MaximShipko, 10 years ago, translation,

Hello!

As many of you have noticed we have new features on Codeforces. The tab “Friends” has appeared on the user ratings page. But it is only the first of improvements made. Now you can view a list of friends on problemset standings, contest registrants and contribution standings pages. Because of increasing popularity of Codeforces the pagination has been added to the rating page.

But that's not all. In order to classify problems, it was decided to introduce the ability to add tags to them. Search by tags is not implemented yet, but administrators and users with high (your color should be at least blue) rating can add tags right now. To do this, simply open the desired problem and add tags in the sidebar form.

As you can see, the project development is actively underway. We would like to hear from you new constructive suggestions.

Updated:

In the near future will be implemented a compact view of tags in the problemset and a setting to show/hide tags.

Maxim Shipko, Codeforces Team

• +84

By MikeMirzayanov, 10 years ago, translation,

The coding phase has been finished. Please wait for the final testing and results.

Good day everybody.

Everything written below is not a April Fool's joke. Though it is also a funny occasion :)

We are glad to announce a new experimental contest on Codeforces, "Problem Parser Contest".

Have you ever made training sessions, using the previous contests' archives? Have you downloaded from the Internet contest archives to test for your solutions locally? If the answer is 'yes', then you couldn't help noticing that each organizer insists upon inventing his own way (format) to distribute problems. Yes, it is true!

I've prepared and organized a huge number of trainings based on the previous contests. It is often rather a monotonous task; one often has to write some scripts that rename the input/output files of the problem into the standard form. In archives they are called very differently: they can be river.in.1, river.out.1, river.in.2, river.out.2, etc. In another problem they can be tests/1.dat, tests/1.ans, tests/2.dat, tests/2.ans etc.

At some point I got fed up with it and wrote a script that told the patterns of paths to the test files, using some heuristics and the regularity I'd noticed. The script worked well, but it wasn't perfect.

• +67

By Ripatti, 10 years ago, translation,
Hello everyone!

I am an author of today problemset. It is my second round on Codeforces. I hope you will like this round like my first one:)

Good luck!

UPD
Winner is unicef.
Editorial.

• +102

By MikeMirzayanov, 10 years ago, translation,

Unusual tournament Manthan 2011 showed the weaknesses of the current rating formulas. After the end of contest the winner of the competition tourist has expected rating change equal to "-1":)

This has arisen due to reduction of the calculated changes in such a way, that total sum is equal to 0. That is, Gennady was in some pros before such changes, but as the sum of all the changes turned out to be positive, then all the ratings were a little reduced. As a quick dirty hack in the round I turned off this feature, leading to a one-time inflation. Even a small mistake: I noticed that participants in the second division get too many points after a good performance on "Div. 2 Only" rounds.