By Ripatti, 6 years ago, translation, In English,

Hello everyone!

Today is the second round of the Open Moscow Programming Championship By CROC will be. Start is planned at 19:00.

Competition will happen by usual rules of Codeforces, with hacks and score falling in process of time. All contestants who passed score no less than contectant of the 300-th place in the Round 1, can participate in the Round 2. Every other contestants can patricipate the Round 2 out of competition. Specially for contestants of the second division we prepared more easy unofficial problemset. The official problemset and the unnoficial one have some common tasks.

Round will be rated for all participants.

Some number of problems are waiting you. They are roughly ordered by the increasing complexity. Score distribution is standard for both divisions (500-1000-1500-2000-2500). Don't forget that during contest your solutions will be tested on a small set of pretests. Testing on full testset will be after end of the round. Pretests can don't cover all cases of input data, so you should test your solutions very carefully.

It is strictly forbidden to publish statements/solutions of the problems before round will be end. Also you shouldn't to talk about problems, discuss some things about possible solutions of them. Let's be honest! You can discuss problems after the end of round.

Top 50 contestant will be allowed to the Final Round. Also all contestant with score not less than score of the 50-th contestant will be passed.

The round was prepared by Ripatti, havaliza, Gerald, RAD, MikeMirzayanov, Delinur.

Good luck for all!

UPD. We remind that the final of the Open Championship of Moscow and Moscow Region Programming (CROC) take place on April 27 in the office of the CROC. Note that CROC does not pay for the road and residence of the finalists. All participants must arrive at the final in the office of the CROC (Moscow) in the morning on April 27.

After the competition all participants will be provided to fill the form on the ability to participate in the finals of the competition. The first 50 participants on the results of the competition, which will confirm their participation in the finals, will be invited to final competition. You can confirm participation in the finals during the day after the end of Round 2.

It is recommended to fill the form, regardless of your results in Round 2, as large number of participants can reject the participation in the final.

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Announcement of Croc Champ 2012 - Round 2
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By ruzana.miniakhmetova, 6 years ago, translation, In English,

Dear all!

Do you already have any plans for the nearest saturday evenings?

If you want to spend it with ABBYY Cup click here to register! There are special checkboxes for pupils and graduates to take part in out of contest.

If want to take part in contest, registration is obligatory. If you are not, it's free.

As MikeMirzayanov commented:

The second division (easy) contest will be a rated event for Div. 2 Codeforces users, so it will be rated for official participants and whose unofficials who is from the Codeforces Div. 2.

The first division (hard) contest will be a rated event for any participant despite of the participant rating and type of participation.

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By undef, 6 years ago, translation, In English,

Hello everyone!

I am glad to invite You to take part in round #115 which is rated for participants of both divisions. As in last year, in this round You will help gamer Vasya to find himself in the virtual world of computer games: brag to his friends about his achievements, determine who is a "noob" and who is a "hardcore" player, destroy the Main Evil, play several rounds of the Plane of Tanks and get rid of the crowd of very bad gnomes. Generally, get a lot of fun!

The round authors are Gerald Agapov (Gerald), Evgeny Lazarev (undef) and Alexey Shmelev (ashmelev). Vladislav Epifanov (vepifanov) and Maria Belova (Delinur) helped us with the round preparation.

In this round You will be given 6 problems, instead of usual 5, also the round duration is increased from 2 to 3 hours.

P.S. Probably You have noticed the contest with strange name "RazMERiq 2012 (Private Contest)". Onsite contest based on Codeforces platform (big thanks to Mike Mirzayanov for the provided opportunity) and problems of this round will be held simultaneously in Nizhny Novgorod. Please, do not register on that contest:)

UPD: dynamic problem max scores will be used in this round.

UPD2: because of a mistake in problem 175B - Plane of Tanks: Pro and changed problem statement, please write a message to Gerald if your solution failed on test 4 because of the problem statement change. Please, specify the submit id in the message.

UPD3: Editorial.

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Announcement of Codeforces Round #115
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By ruzana.miniakhmetova, 6 years ago, translation, In English,

The ABBYY company, a leading provider of document recognition, document capture, is holding a student online ABBYY Cup contest together with the Codeforces and Saratov State University. We’ve been taken into account the feedback from the previous contest into consideration. So, this year’s contest will consist of two divisions.

If you belong to the second division on Codeforces, that is, if you’ve never participated in programming contest or have little experience of participating, then your best choice is to apply for participating in the second (easier) ABBYY Cup division. This division will have problems that are even easier than those given on ABBYY Cup 1.0. The first (and more difficult) division will be mainly interesting to the first division Codeforces participants, that is, to those who have considerable experience of sports programming.

We thank Gena Korotkievich for taking part in preparing the problem set.


Each division will contain 6 problems, each problem will cost 100 points. The official languages of the contest are C/C++, Pascal, C# and Java. You can submit problems on any languages that are supported by Codeforces. However, the jury does not guarantee that there exist full solutions in all languages from the list. Only fully passing a group of tests is counted. When contestants win the same number of points, the penalty time is counted by the ACM rules. Fully solving some group of tests is counted as submitting an ACM-problem and will determine the penalty time you get.

The second division contest starts on April 21, Saturday, at 6.00 PM. The contest duration time is 4 hours. The tests are split into two categories (easy and difficult), they are worth 30 and 70 points, respectively. These contests are officially available to those who is included in the Codeforces’ second division. The Codeforces’ first division users can take part in the second division out of competition.

The first division contest starts on April 28, Saturday, at 4.00 PM. The contest duration time is 5 hours (the problems are worth it :)). The tests are split into three categories (easy, moderate, difficult), they are worth 20, 30 and 50 points, respectively. Anyone regardless of their rating can participate in this contest.

The registration will start on April, 16 on ABBYY Cup official page!


We invite all participants to the ABBYY Open Day. There we will talk about our technologies and give awards there. The winners of the difficult division will be awarded valuable gadgets and will also receive compensation of their expenses spent on the road to Moscow and back. The date of the event will be announced later. You can read about the Open Day in ABBYY for the ABBYY Cup 1.0 winners on the site of the contest and in Alex_KPR's blog, who participated in the Olympiads and won it.

See you in ABBYY!

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By Burunduk1, 6 years ago, In English,

Hello everyone!

Today, 8-th of April, the third round of the VK Cup 2012 will take place. It's the last selection round. Let me remind you that the registration for this round is also required and it’s closed five minutes before the start.

It's rated round. It's allowed to participate out of competiotion. For all such participators it's also rated round. If you participate out of competition, you may play in the second division.

The problemset has been developed by various authors from VK, Codeforces and Saratov State University.

We worked hard to make problems more hard than usually but solvable in two hours. We hope, participation in the round will be interesting for you and only best of the best will pass to the Final Round.

This round will be run according to Codeforces rules: with room assignments, hacks and usual score decrease. It will be rated for you either if you participate in VK Cup or just solve it as a normal round.

Top 50 competitors will advance to the Final Round. VK Cup Final will occur in July in Saint-Petersburg.

Please, to make the round even more interesting for you, read the statements of ALL problems.

Good luck and try to win!


In Div. 2 Edition it will be used dynamic problem costs The problems will be ordered by increasing of expected difficulties, but their max scores will be determined according to the number of participants solved them.

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Announcement of VK Cup 2012 Round 3
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By Nickolas, 6 years ago, translation, In English,

I'm a huge fan of Surprise/Unknown Language Round competition format. Theoretically I enjoy participating in them, but in practice I mostly run them. What's so special about them that makes me like them so much?

  1. They are unusual. At some point of time (which arrived pretty soon for me) traditional competitions pall and become a blur. If I give it a thought, I can clearly remember only a couple of the 80 SRMS and CF rounds I've done. The SRM which featured MooresLaw problem (great challenge phase and my only ever room win), TCO elimination round which I passed thanks to a last-minute submission on 500pt, a GCJ round from back when it was held on TopCoder platform, when I got stuck at input parsing and never got to the actual solution... and that's all. Marathon memory is a bit better, probably because I've participated in fewer of them, and each match took more time and effort. But unusual competitions leave the most lasting and vivid impression.

  2. They fit my skills. I'm not the one to get intimidated, let alone scared by a language which misses loops, strings or anything else from the commonly used programmer's toolkit. Well, there are a couple of languages which I'm uneasy about, but they are very unlikely to appear in an ULR.

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By MikeMirzayanov, 6 years ago, translation, In English,

Hi everybody!

Let me remind you that on the 3rd of April, at 08:00 the Qualification Round of the Open Moscow Programming Championship By CROC will start.

You need to participate in the Qualification Round to make it to Round 1. Contestants who gain a score equal to the 1000-th place finisher score or greater will advance to the Round 1 (also you need to gain positive score).

At the Qualification Round you will find a few simple problems, roughly ordered by the increasing complexity. During the Qualification Round the problems are judged only on pretests and system testing will take place after the end of the Qualification Round (round continues for 24 hours). The pretests do not cover all possible cases of input data, test your programs carefully! The Qualification Round has no hacks or decreasing values of the problems.

The round will last for 24 hours, but it does not mean that we encourage you to spend all this time solving of problems. We hope that most participants will cope with the problems (or with most problems) in a shorter period of time. This duration of the round is chosen so that each participant could find a convenient time to participate.

Before the end of the round it is strictly forbidden to publish the problem statements/solutions/any thoughts and ideas about them elsewhere. It is forbidden to talk about the problems, discuss the statements and so on. Be honest and let the best men make it into Round 1. When the Qualification Round is over, you can discuss the problems and solutions.

You can register for the round at any time up to its end.

The results of the round will not affect the rating, non-competitive participation in the round is not allowed. However, all tasks will go to the archive after the end of the round.

Best of luck and enjoy solving the problems!

UPD: The contest is over! Thank you for your participation. We will remove cheaters soon and the results will become official. Unofficially, the Round 1 cutoff is 1950 points.

UPD 2: We have removed obvious cheaters and people who are under 18 years old at the time of registration. If your results have been removed in error, please contact me for clarification. Now, the Round 1 cutoff is 1900 points.

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By Nickolas, 6 years ago, translation, In English,

Congratulations to KADR who was the first of two people to solve all 8 problems!

171A - Mysterious numbers - 1

The easiest way to make the problem statement unusual is to omit it. This is an extremely convenient approach — you don't have to maintain the statement in two languages or to worry that it might turn out to be ambiguous or too long or too scary. 690 people solved this problem, so evidently we can omit statements even in regular rounds :-)

As for the problem itself, it required to sum the first number and the reverse of the second number.

171B - Star

They say it's better to see once than to hear ten times or to read a hundred times. In this problem we decided to check this and to replace the traditional textual statement with a single image. Same as in the previous problem, it did well — at least 645 participants recognized star numbers (sequence in OEIS), the numbers of balls needed to form a six-pointed start of certain size. After this one had only to code the formula —

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By Nickolas, 6 years ago, translation, In English,


You might have already noticed the next contest in the events calendar, the one named April Fools Day Contest. The name hints that the contest is unusual, nowhere near serious and maybe even snide. One could even guess the author of the contest — the meanest of all out there, that would be me :-)

I love unusual contests — Surprise/Unknown Language which require solutions in unusual languages, Time Limit Exceeded which require solutions in C but written in an unusual manner... Most of such contests exploit the domain of unusual solutions. I've decided to take a peek at the dual domain — unusual problem statements.

In this round you'll be given several weird problems and 2 hours to solve them. The contest will be unrated (you bet!), and it will follow ACM ICPC rules (no hacks, the standings are decided by the number of solved problems and penalty time earned on them). You can submit solutions in any language allowed by Codeforces — of course, unless the problem says otherwise :-)

Be warned, to enjoy competing in this round you'll need a sense of humor compatible with mine! It's April Fools Day, after all. Enjoy!

P.S. This contest exists solely due to maksay who volunteered to do all technical preparations. Thanks!

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Announcement of April Fools Day Contest
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By MikeMirzayanov, 6 years ago, translation, In English,


Welcome to the VK Cup 2012 Wild-card Round 2!

It will be a week-long contest with the only problem. It seems the problem doesn't have an exact solution. So as better answer your solution finds as more points you'll get! Of course, it is not all the details. Full text of conditions and the rules of scoring you will be able to read immediately after the round starts.

If you was an official VK Cup 2012 Round 2 participant but didn't advance to the Round 3, you have the last chance to do it! Take part in VK Cup 2012 Wild-card Round 2 and be in the top 25 to advance to the Round 3. All others are members of the community can take part in the round out-of-competition, just for fun. Anyway, it will be unrated round to any of you.

Remember that after the contest ends your last attempt which passes at least one test will be judged on the main testset. You may try to solve problem as many times as you want.

Good luck! Let the best man win!

P.S. I must leave it here. During the contest is strictly forbidden to post/discuss algorithms/approaches for the problem, share any conclusions about the problem. You can not share the results (including just report score points) of the solutions on any tests. It is prohibited to publish tools to simplify and automate the process of solving the problem.

Thanks Nickolas, for the great problem!

UPD: The contest is over, the testing is completed. Congratulations to the first 25 finishers — standings, you are in the VK Cup 2012 Round 3!

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