Hi all! :)

I (Untitled) invite you to participate in Codeforces Round #178 (Div. 2) which will be held today. I want to thank Gerald Delinur MikeMirzayanov for their help in preparation of this event. I also want to thank havaliza who tested the round and made the graphics for the problems.

The hero of today's contest is Shaass. Hope you enjoy helping him! :D

Good luck and have fun ;)

UPD. Editorial is partially out and will be completed soon! :{

ABBYY Cup 3.0 is coming! Within the Cup we announce the programming problem contest. Best problems will go to ABBYY Cup 3.0 and best authors will win prizes!

A problem should include:

You can also add a complexity level (easy, medium, hard) and your ideas about modifications. We are interested in "heuristic" problems besides "classic". An example of a heuristic problem from the ABBYY Cup 2.0 is here.

All problems must be new i.e. invented by you. Every contestant can send no more than three problems. If your problem does not go to ABBYY Cup 3.0, we promise to keep it in secret. Jury members are no longer participants of programming contests and they are not interested in using your problems apart from ABBYY Cup.

Please send your problems in .pdf, .doc, .docx, or .txt format to abbyycup@abbyy.com with subject "ABBYY problem contest". Problems are accepted from 8 to 21 April. Write your name, surname, school and graduation year. It is desirable to write your Codeforces handle. Be sure that you receive the answer which confirms receiving your email!

We hope that our problem contest will be held every year and will help to find new talants and make ABBYY Cup more interesring for contestants!

Greetings!

Codeforces Round #177 takes place tomorrow at 19:30 by Moscow. I hope you all will take part and enjoy the problems.

Gerald, as usually, helps in preparings, Delinur translates all the problems for you. Thanks to them.

Good Luck!

Points distribution is standard:

Div1: 500 1000 1500 2000 2500

Div2: 500 1000 1500 2000 2500

Here are today's winners:

Div1:

1. wjmsbmr

2. peter50216

3. rng_58

4. XilinX

5. RAD

6. RomaWhite

7. eduardische

Div2:

1. alimiaomiao

2. yutaka1999

3. Alex.lap

4. zlqiszlq

The contest is over; I hope you've enjoyed it. 1465 participants submitted at least one problem correctly. Unfortunately, nobody managed to solve all 6 problems; congratulations to ShadowSong who won the contest by solving 5 first problems with the lowest penalty time!

290A - Mysterious strings

Last year we've verified that a lack of problem statement doesn't prevent participants from solving and submitting the problem successfully and at the same time saves the problem setter some writing effort. This year we've ascertained this again. Well, I could've invented a long and knotty legend about you, a young but very promising software developer, were summoned to White House and given a task of utmost importance: to deliver an interactive list of USA presidents from founding fathers to our days. It could have featured a dramatic time-consuming search for necessary info, pursuits, firefights, a wounded teammate whose dying words were "Eight is Van Buren, don't forget... print Van, just Buren... doesn't pass". But what for?

The contest editorial is available here.

Some jokes are fun only for the first time, repeating them makes them lose their charm. I certainly hope that April Fools Day Contest is not the case, but there's only one way to verify this :-) I'm happy to invite you to take part in the verification process which will take place on Monday April 1st. Let me disprove the suspicions some people have: the joke is the contest contents, not the fact of its existence or the lack of it — that would have been too simple :-)

In this round you'll face 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. To get an idea of what awaits you, you can have a look at the last year's contest.

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

Upd. Registration is open till the end of the contest.

As the TopCoder TCO 2013 Round 2A did not take place as planned but was moved (with sniper precision) right on the place of the Codeforces Round #177, we decided to reschedule the contest. I have to admit that my first urge was to leave everything as it is — TopCoder knew of Codeforces Round 177 and I cannot approve of such an approach to solving their technical issues. On the other hand, no fault lies on the community, and especially on dear witua, the writer of the forthcoming round. You’d like to participate and the writer is keen on making a round as popular as it gets. Besides, the problem coordinator Gerald would have fallen under much pressure, juggling work and TCO. That’s why the Codeforces Round #177 moves to the time that was initially planned for Round 178, and Round 178 moves a little ahead.

We apologize for the schedule inconveniences and hope to see you among the Codeforces Round #177 participants. It will be fun!

We are growing and spreading! All-Russian Programming Championship CROC-2013 is followed after the Open Moscow Championship and the Championship for the Bauman MSTU Students.

The CROC company, with the help of Codeforces and Saratov State U, sets up a competition for the top talented programmers of the country. If you are a university student or a young specialist over 18 (and the citizen of Russian Federation), we invite you to participate. The first prize in the Championship is 100000 rubles, the second prize is 70000 rubles and the third prize is 50000 rubles.

Championship Schedule

*the championship can be expanded if the number of participants exceeds expectations, all finalists should to confirm invitation until May 2

• Qualification Round – April, 13-14
• Elimination Round 1 – April, 15 (up to 2000 participants)
• Elimination Round 2 – April, 22 (400 participants)
• The championship finals are going to take place on May, 16-17 in Moscow in the CROC office (50 participants)

The rules will be explained in more detail a little later, but no surprises are planned. We will try to involve the "out of competition participants" (that is, those who can't officially participate in the Championship) as much as possible.

Some pleasant surprise awaits for the participants in the dream office and outside it! The CROC company pays for the accommodation in Moscow during the finals. Also for Russian citizens the travel expenses around Russia will be covered (* The transport expenses outside Russia can be covered possibly partially but you need to contact us and clarify it for each particular case). The official event language is Russian, the problems will be in Russian and English.

Registration

To participate in the championship, you need to register on the championship page, website crocok.ru. The registration will be available until the qualification is completed. Compete with the best coders on an Open Programming Championship!

Register Now »

Hi all! This round was prepared by me and KAN. I hope, you will enjoy our problems.

I want to thank PavelKunyavskiy, who tested our problems, readed statements and so on. Moreover, alger95, Skird, fdoer, sand-martin tested round too, I thank them for it.

And of course, I thank Gerald for organising our work, MikeMirzayanov for the great system and Delinur for translation of the statements.

I hope, result will be better than results of our previous round. Good luck!

Pay attention, round will be held at unusual time.

Scoring:

div1: 500-1500-1500-2000-2500

div2 : 500-1500-1500-2500-2500

My congrutulations for leaders.

div1:

1. al13n
2. tomek
3. niyaznigmatul
4. voover
5. Egor
6. Zlobober
7. White_Bear
8. seanwu
9. wjmsbmr
10. peter50216

div2:

1. fotiIe96
2. zfmdhy786
3. wzc1995
4. gjh
5. mynameisverylong

Full english editorial: here

Good day, friends)

Welcome to regular Codeforces round #175 for Div.2 participants. Traditionally Div.1 participants can take part out of the competition.

The problems were again prepared by the group of authors: Pavel Kholkin (HolkinPV), Artem Rakhov (RAD), Fefer Ivan (Fefer_Ivan) and Gerald Agapov (Gerald). Traditionally thanks to Michael Mirzayanov (MikeMirzayanov) for Codeforces and Polygon systems and Mary Belova (Delinur) for translating the problems.

Score distribution is published in advance) today it is standard: 500, 1000, 1500, 2000, 2500.

We open the little secret of this competition, in all today's problems you find permutations)

We wish everyone good luck, successful hacks, high rating and good mood)

UPD1: the contest is over, hope you enjoy it)

UPD2: the tutorial is already published here)

UPD3: congratulations to winners:

1) hechuan
2) TroyI118
3) BekzhanKassenov
4) ahmed_aly
5) lxgsbqylbk

Hello everyone! Codeforces Round 174 will be held for both divisions on Sunday, March 17th at 7:30 PM MSK. The problem setters are abacadaea and me (scott_wu). We would like to thank Gerald for his help in preparing the contest and Delinur for translating the problems. We also thank MikeMirzayanov for creating such an awesome site. We are very excited as this is our first Codeforces round.

For this contest you’ll be helping Farmer John, Bessie, and the cows. We hope you enjoy the problems! :)

The score distribution will be slightly nonstandard.

Div2 — 500 — 1000 — 2000 — 2000 — 2500

Div1 — 1000 — 1000 — 1500 — 2000 — 2500

Good luck and happy coding! As always, to make the round more exciting, we recommend that you take a look at all the problems!

UPD: Our editorial can be found here. Thanks for participating!

Congratulations to the winners:

Div1

1. al13n
2. rng_58
3. HELEN_KK
4. wjmsbmr
5. bmerry

Div2

1. hockey_for_NOI
2. Efremov_licesos
3. Muali
4. koratel
5. lxfind