Hello everyone!

Codeforces Round #153 will take place on Thursday, December 6th at 19:30 MSK. This is my third Codeforces round and I hope there will be more.

I'd like to thank Shtrix, Seyaua, sdya and Gerald for helping me to prepare the round. Special thanks to Delinur for translation of all problem statements into English.

I hope you will like the problems.

Good luck and have fun!

UPD: Complete version of English editorial is now available.

Congratulations to the winners!

Division 1:

1. Egor
2. tourist
3. rng_58
4. kelvin
5. Burunduk1

Division 2:

1. inker
2. WhoTheHellIsMe
3. memo1288

Northeastern European Regional Contest 2012 will start on December, 2nd. We wish good luck to the teams and many joyful moments to the funs!

Useful links:

• standings
• Petr Mitrichev blog
• Online translation of Awards Ceremony

Good day!

For technical reasons, we've decided to move the start time of the online version of the round. Online version will be held as separate competition CROC-MBTU 2012, Final Round (Online version, Div. 2). Please register for this competition.

This round will be usual rating round for the Div. 2 participants.

UPD. The online version of the round will come soon. Let me remind you that this contest will hold by usual Codeforces rules. The score distribution is 500-1000-1500-1500-2000.

Enjoy contest!

Hi, everyone!

The authors of Codeforces Round #152 are am-real, max777alex and me.

Special thanks to Gerald who helped us to prepare this round. Also, we want to thank Delinur for english statements. And we'd like to thank Seyaua and sdya for reading and testing problems of this round.

The round will be held on 25th of november at 19:30 in Moscow time, and it will take place in both divisions.

Score distribution div1: 1000 1000 1500 1500 2500

Score distribution div2: 500 1000 2000 2000 2500

Contest is over.

We appologize for ambiguity in the statement of the problem A. It was not clear whether it is possible to touch the goal post when the ball crosses the goal line. However, both ways to understand the problem statement were accepted. These solutions differ by an infinitesimal amount. The only thing that this ambiguity has effected a lot — hacks. All the hacks, which were based on the assumption that such touching is impossible, will be removed. Please, those who have done these hacks inform Gerald Agapov (Gerald).

We also apologize for the interuptions and problems with statements rendering.

Far from unanimous decision of the jury, it was decided to make this round rated. The rating will be recalculated on 26/11/2012 after removing of all relevant hacks.

Welcome, dear friends)

We are glad to introduce you regular Codeforces round #151 for Div.2 participants. Traditionally the others can take part out of the competition.

Today's problems were prepared by authors: Pavel Kholkin (HolkinPV) and Gerald Agapov (Gerald). Traditionally thanks to Michael Mirzayanov (MikeMirzayanov) for perfect Codeforces and Polygon systems and Mary Belova (Delinur) for translating the problems.

Score distribution will be standard.

We wish everyone good luck, successful hacks and high rating!

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

Congratulations to winners:

1. a58 (he solved all 5 problems)
2. thangpc
3. Minecraft
4. xiaoshua3
5. Noskov

UPD2: you can find the editorial here

Good day!

Elimination round of the CROC Collegiate Programming Competition for the MSTU Bauman students is going to be here soon. The official championship participants will take part in the competition, all others will be out of the competition in the table of results.

The contest is held by the well-known rules ACM-ICPC. Competition duration is 2:00 hours. Supported programming languages are C/C++, Pascal, Java, C#, Python, Ruby, PHP, Haskell, Scala, OCaml, and D.

This Round will be the rated for the Div-2 participants, regardless of whether one is the competition championship party or not. For Div-1 participants this round is unrated.

Please note that the official participants of the competition are not need to register for this competition they will be registered automatically (with advance registration at website).

Good luck to everyone!

UPD. Competition is completed, thank you very much for your participation! I hope that the problems with the queue is not much to spoil your impression of the contest. The results of elimination round for official participants will be announced tomorrow. Rating will be update soon.

Hi all!

That's the 150th (anniversary?) Codeforces Round. For the 1st and the 2nd divisions both.

Round is prepared by Ripatti , Gerald , Delinur .

Enjoy!

UPD. Points are standard: 500-1000-1500-2000-2500 for both divisions.

UPD2. Contest complete. Cheaters are deleted. Ratings are updated.

Div1 winners:
1. scottai1
2. vepifanov
3. rng_58
4. Egor
5. Komaki

Div2 winners:
1. mochavic
2. hanamaki
3. mfv
4. shef_2318
5. TangJie

Thank you for your participation. Come again.

Editorial will be tomorrow.

UPD3. Editorial. Sorry for delay.

Hi to all!

A few hours later you're lucky to participate in Codeforces Round #149 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), Pavel Holkin (HolkinPV) and Gerald Agapov (Gerald). Also we express thanks to 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 is over, thanks to all!

UPD: Congratulations to the winners:

1. Fio

2. ballmaids00

3. mihaipopa12

4. Yukari

5. chlxyd

UPD: the tutorial has been published.

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.net/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