Hi all! :)

I'm glad to invite you to participate in Codeforces Round #148 today. I (Hamed Valizadeh) am the author of this round.

I'd like to thank Gerald (Gerald Agapov) MikeMirzayanov (Mike Mirzayanov) Delinur (Maria Belova) and Saeed_Reza (SaeedReza Seddighin) who helped me in preparing the round.

Score distribution will be the standard 500-1000-1500-2000-2500 in both divisions.

Hope you find the problems interesting to solve.

Good luck and have fun ;)

Update. Contest is over. Congratulations to the winners of both divisions! :)

Div1:

1. tourist
2. cerealguy
3. Dmitry_Egorov
4. RAVEman
5. UESTC_Nocturne

Div2:

1. LiWenHaoTianXiaDiYi
2. goooooooopan
3. jthread
4. kolina
5. xcodevn

And congrats to Endagorion who was the only one solving 238D - Tape Programming correctly during the contest.

BTW, I hope you didn't get sick of that boring problem! :-"

Update 2. The editorial is ready now, sorry for the delay. http://codeforces.com/blog/entry/5765

Elimination round is over!

Thank you all for participating in the elimination round of Bayan Contest. The final results are available. We had more than three thousand registered users for the contest on Codeforces and one third of them were able to solve at least one problem. In the meantime 1100 Iranian contestants participated in our local contest and half of them solved a problem.

We tried hard to prepare a challenging-yet-fun problemset.
The problem "241G - Challenging Balloons" was inspired from a real story! The problem described in the story was used in CEOI 2011 (Task Balloons), and the provided algorithm was the author's solution during that contest — which got the full mark indeed.
According to statistics, "241D - Numbers" was the hardest problem. A tricky approach to the solution is to ignore large inputs and solve the problem for small values of n. You may observe that it is possible to find the demanded subset within a small part of input. During the contest, no one solved all the problems but there was at least one successful attempt for each of them.
We hope you enjoyed it all!

As stated before, Top 100 contestants will be receiving T-shirts. So, update your contact information and T-Shirt size in your Codeforces profile. We'll start sending the prizes as soon as possible.

And the winners...

The winners will receive invitation letters — to the on-site event — soon. If you are one of them make sure your contact information is up-to-date.

Congratulations to all the participants, specially the winners. See you in Tehran!

Good Luck

Hi everybody!

Time for Bayan Programming Contest 2012/13 — Elimination Round.

The problemset has been prepared by Bayan employees. We've tried our best to make it interesting, competitive and a little-bit different! We'd like to thank Mike Mirzayanov (MikeMirzayanov) and Gerald Agapov (Gerald) who helped us during problemset arrangement process.

The contest is individual and will be held with ACM-ICPC rules. It will be having English statements only. Also, it will be rated for Div-1 contestants, but we expect Div-2 participants to enjoy it as well.

This round will be a 3hr round with 7 problems to solve. Just like most of ACM-ICPC contests, problems are not supposed to be sorted in order of difficulty. Also, the registration will be open until the end of contest, so be sure to double-check the timing.

Top 20 participants will be invited to the onsite event — Tehran, and Top 100 will be receiving T-Shirts. More details about the prizes is explained in our previous blog post.

Just to emphasize some rules, avoid participating with more than one usernames. Also, you should not collaborate or contact anyone about the problems.

Good Luck!

UPD: The contest is over. Congratulations to all the winners, specially:
1. tourist
2. cerealguy
3. rng_58
4. peter50216
5. Egor
6. PavelKunyavskiy

Because of unusual calculation of rating for this contest. The rating will be updated with delay.

Good day, Codeforces!

Please note that there have been significant changes in the schedule of competition! Competition Codeforces Round #148 rescheduled for Sunday, also added new competition Bayan 2012/13 Elimination Round.

The latter is an elimination for the BAYAN 2012/13, as it is sure to be a rated round for participants from Div1. The issue of rating for participants from Div2 currently being addressed. Do not pass by, registration starts now!

Please note that the competition Bayan 2012/13 Elimination Round will held by the ACM ICPC rules, and the statements of this competition will be available in English only.

Gain your strength before the upcoming competition! Good luck to all!

I will be hosting Petr Mitrichev Contest 10 this Saturday (October 27) between 15:30 and 20:30 Moscow time (other timezones: http://timeanddate.com/worldclock/fixedtime.html?msg=Petr+Mitrichev+Contest+10&iso=20121027T1530&p1=166&ah=5 ).

The contest will be held at http://codeforces.com/gyms . Both teams and individual participants can join. The contest itself will be at http://codeforces.com/gym/100110 , but this link will be accessible only after the start of the contest.

There will be 10 problems of varying difficulty (most are quite difficult) for 5 hours. Your solution needs to be correct on all test cases to be accepted (the standard ACM ICPC rules). People will be ranked by the number of solved problems, and by total penalty time in case they're tied on solved problems, so don't be late! :) Note that in each problem you need to read the input from a file and write the output to another file — so don't read from stdin and don't write to stdout! Problem statements will be in English.

Feel free to ask any questions that you might have, and also please tell if there are any issues with the contest system — it's the first time I'm using codeforces.com/gyms .

Registration: http://codeforces.com/gymRegistration/100110

5 minutes before start, good luck everyone!

Solution ideas: http://petr-mitrichev.blogspot.com/2012/10/petr-mitrichev-contest-10-solution-ideas.html

Hi!

A few hours later you're lucky to participate in Codeforces Round #147 for Div.2 participants, but traditionally the others can take part out of the competition. It has been prepared by me (NALP), Igor Kudryashov (Igor_Kudryashov), Pavlik Holkin (HolkinPV), Gerald Agapov (Gerald), Mary Belova (Delinur) and Mike Mirzayanov (MikeMirzayanov).

Traditionally I wish good luck, accepted solutions and successful hacking attempts for you!

The standart scoring system will be used: 500-1000-1500-2000-2500

UPD: The contest has ended, congratulations to the winners:

1. try_skycn

2. AntiKismet

3. dianbei_03

4. Uncia

5. Bigsophie

Hi!

Codeforces Round #146 is going to be here soon. Round is prepared by YuukaKazami, MinakoKojima. I write problems for Div I and MinakoKojima write for Div II. Gerald did a great job in coordinating round preparing, and he also give some pretty good advise about problems. I'd like to express my gratitude to him. Traditionally thanks to Michael Mirzayanov (MikeMirzayanov) for perfect Codeforces system and Polygon system as well and Mary Belova (Delinur) for translating problems. Also thanks to donehl for testing the problems and making his comments about the problems.

Score distribution is 500-1000-1500-2000-2500 in both divisions.

Hope you enjoy the problems! =)

I apologize for the 10 minutes delay.I'm very sorry for the inconvenience I caused. So I'm writing a good editorial for compensation :)

The Editorial is here: Editorial

Congrats to winners!

Div1:

1.rng_58

2.Dmitry_Egorov

3.bjin

4.Petr

5.Egor

6.tourist

Div2:

1.RiKang

2.Caesar11

3.Gabaum

4.ilona

5.Bidhan

6.sm_hossein

Good day, Codeforces!

I can't wait to give you a good news that a new competition for div1 participants is appeared in the list of events. This competition is a broadcast of the Saratov Team Olympiad on Programming and therefore will be held by the ACM-ICPC rules. Especially for div1 participants, we complicate this school competition a bit, so that everyone was interested to solve the problems.

This Competition is individual, it will be rated for both divisions.

Please note that the start time of the competition is different from the usual. Also note the unusual length of the competition.

See you at Codeforces Round #145! I hope that everyone will find the time to participate in the competition.

UPD. The competition finished, the editorial will come soon.

Hi all!

Codeforces round #144 is going to be today.

Round is prepared by: KAN, fdoer, Skird, tunyash. Special thanks to Gerald for coordinating round preparing, many awesome ideas and making statements easy-understandable. Also I thank MikeMirzayanov for enjoyable problem-preparing system, Delinur for statements translation.

I hope, that all will be well and you will enjoy solving problems.

Good luck!

UPD: Score distribution will be announced a few minutes before the start of the contest.

UPD2: score distribution is 500-1000-1500-2000-2500 in both divisions

UPD3:

Congrats to winners.

div1:

1. tourist
2. rng_58
3. Mimino
4. Dmitry_Egorov, Egor

div2:

1. debug22
2. ryz
3. dvdreddy
4. vinodreddy
5. rdivyanshu

UPD: editoral for all problems, except div1.D is ready

Hi to all!)

Codeforces #143 for participants from second division is going to be today. I think, it is not necessary to remind, that coders with rating greater than 1699 will be able to take part out of the competition.

Problems' autors for this event are Kholkin Pavel (HolkinPV) and Kuznetsov Nikolay (NALP). Kudryashov Igor Igor_Kudryashov and Agapov Gerald (Gerald) helped in contest's preparation too. Special thanks to creator great resource Codeforces Mike Mirzayanov (MikeMirzayanov) and our translator Maria Belova (Delinur).

Score distribution will be determine later, monitor for changes).

We wish you enjoy participating this competition and want you to get something new and useful.

UPD: Score distribution will be standart 500-1000-1500-2000-2500.

UPD2: Round is over. Thanks to all for participating. Six first coders solved all 5 problems, congratulations.

1) teoy

2) gomineral02

3) mrNobody

4) Ryannnnnnn

5) marschenly

6) KuchumovIlya

Editorial will be published soon.

UPD3: Editorial is published, you can find it here