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 http://oeis.org/A003154 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 —

Editorial

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!

Hello!

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!

I am sorry for mistakes in English and I will be glad if you tell me about them.

168A - Wizards and Demonstration Аuthor PavelKunyavskiy.

In this task, it was necessary to write exactly what has been described in statement. In particular, it was necessary to have people, who come to the meeting. For this it was necessary to create clones.

168B - Wizards and Minimal Spell Аuthor PavelKunyavskiy.

In this problem you had to write exactly what has been described in statment too. Read lines one by one. Also keep the last block of lines that are not amplyfying. If the next line is amplyfying (which can be checked by linear search), we print the last block, if any, and the line itself. Otherwise, remove all spaces from the string and add to the last block.

Hello!

We are happy to invite you to participate in today's round. I hope everyone will find interesting problems for him. And most of the round participants will like it as well as the previous one.

Today's contest was prepared for you by SPb SU 4 team (Alex-Gran (Alexandr Granovskiy), Dmitry_Egorov (Dmitry Egorov), PavelKunyavskiy (Pavel Kunyavskiy)). After long thoughts you can notice that we present St.Petersburg State University.

Thanks very much for help in the tasks preparation to Artem Rakhov(RAD), Gerald Agapov (Gerald) and Maria Belova (Delinur) for translation statements. Also thanks to Petr Kalinin (KAP) for statements proofreading.

In today's contest there will be seven problems (5 in each division) about the country where wizards live, and this causes many interesting events. Today you have to take part in local meeting, understand the intricacies of writing spells, ride on the magic transport, try to take away magic prizes, play in popular wizards game, help magic government in ruling the country and resolve financial dispute of two famous wizards.

Scoring is standard is standard in both divisions today (500-1000-1500-2000-2500).

UPD: analyse was published.

Good luck!

Hello everyone!

It’s time for the second round of the VK Cup 2012. Let me remind you that the registration for this round is also required and it’s closed five minutes before the start.

The problemset has been developed by various authors from VK, Codeforces and Saratov State University. We worked hard to make this time interesting for competitors and to have the best ones in the next 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 175 competitors will advance to the second round immediately. 25 more competitors will advance to the second round via the second unusual rules wildcard round on March 28. This round will consist of only one problem with inexact solution.

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

Good luck and try to win!

Hello.

VK Cup 2012 Round 2 will be held in two editions:

• official VK Cup 2012 Round 2 — for official advancers to VK Cup 2012 Round 2 and for the coders from Division 1 (them will participate out of competition),
• special VK Cup 2012 Round 2 (Unofficial Div. 2 Edition) — for participants from the second division, who is not an official participant of VK Cup 2012 Round 2.

In each of these editions the ratings will be updated (separately). In the first edition the ratings will be updated according to the results of participant of both types: official and unofficial. Ratings of the participants of both types will be updated. In the second edition it is easier — there is only one type of participants and and their ratings will be updated in typical way.

On March 18 Samara Interacademic Programming Contest was held. It is one of two Collegiate Programming contests, which are organized in Samara every year.

Everyone can take part in this contest as a Codeforces Gym contest. Like any train, this contest uses ACM ICPC rules.

Problem writers are Alexey Dergunov(dalex), Nikita Glashenko (Hohol), Pavel Semushin (craus) and Andrey Gaidel (Shlakoblock). Testers are Natalia Bondarenko (natalia) and me (I_love_natalia).

Contest will be most interesting for participants with color from green to orange (Difficulty is 3 stars). Red participant most probably will spend much less time than 5 hours for solving all problems (both of testers finished it in about 3 hours).

Train will be held on Saturday at 16:00 MSK. Everyone is welcome to participate.

Please, do not use any prewritten code and any internet materials in token of respect to ghost participants who will compete with you ;)

Upd. Time was changed to 16:00 (MSK, UTC+4).

Upd2. Don't forget to use input.txt and output.txt files instead of stdin/stdout.

Upd3. Do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64d specifier.

Welcome dear friends)

We are glad to introduce you regular Codeforces round #113 for Div.2 participants. Everyone can traditionally participate in it.

Problems are prepared by known command of authors: Kholkin Pavel (HolkinPV), Nikolay Kuznetsov (NALP), Artem Rakhov (RAD). Also thanks to Gerald Agapov (Gerald) for his help, Michael Mirzayanov (MikeMirzayanov) for Codeforces system and Mary Belova (Delinur) for translating problems.

In todays contest would be one innovation. Score distribution would be dynamic. More information you can find here)

We hope that todays round would be succesful. We wish you good luck and high rating!

UPD: The contest is over. Hope you enjoy the problems) the editorial is already here)

Congratulations to winners:

1. Avalanche

2. seiya

3. Konon

4. yongheng5871

5. I_dont_have_girlfriend

6. ibra

7. Doriam30

8. unknown79

9. UESTC_Hetalia

10. lisang

CROC invites talented and innovative programmers (at least 18 years old) to participate in the Open Moscow Programming Championship. The championship is held on the basis of the Codeforces project. Saratov State University involved into jury and the technical committee. The official championship language is Russian, but the problems will be in Russian and English.

The championship will consist of qualification, two online rounds (on April 3-4, 6 and 20) and the final round that will take place on April, 27 in Moscow in the CROC Headquarters. The championship finals will also include a AI-game round.

The championship winners will be awarded with valuable prizes: the first place winner gets 100000 rubles, the second and third place winners get Apple MacBook Pro. The contestant who wins the first place in the AI-game round will be awarded with an Apple MacBook Air.

To participate in the championship, you must register on http://www.crocok.ru/championship/ (in Russian) before April 4, 2012.

You can also learn more about the project if you follow the link http://crocok.ru and click the tab called "Programming Championship".