Hey everbody.

Hello 2015 is a Div.1 + Div.2 contest that will be held in gym soon. As I said, there will be 2 divisions and in each divisions, users of that division can participate ( ( - ∞, 1699] and [1700, 9999]). So, anybody who participates in the wrong division will be out of competition (manually).

Duration is 3 hours and there will be 6 problems in each division. Last 4 problems of Div.2 will be same as first 4 problems of Div.1 . Problems are written by me (PrinceOfPersia) and tester's M.Mahdi.

The problems will be sorted according to the estimated order of difficulty according to my opinion but I strongly recommend you to read all of the problems.(sentence from matrix :D).

Problems are more Olympiad style than ACM. I hope you enjoy them.

It takes a while to prepare all problems. So, this contest is not in the gym contests list yet.

Oh, I almost forgot this : the main character of all problems will be my friend, De Prezer :)

UPD: Problems are designed for single participant (as mathlover said), so teams will participate out of competition too.

UPD2: It's in the gym contests list now.

UPD3: For making the contest more interesting, the winner of each division, gets a kiss ;)

UPD4: Round was delayed by 10 minutes for some technical reasons.

UPD5: Contest is over.

Congratulation to all winers specially sankear who solved all Div.1 problems.

Div.1 winners :

1.sankear

2.ikbal

3.kraskevich

4.tourist

5.dreamoon_love_AA

Div.2 winners :

1.cthbst

2.peterpan

3.que_roin

Now it's time to sankear and cthbst kiss each other ;)

See you in next rounds, good luck and have fun.

UPD6: Well, recently I'm a little busy and I'll just post some keywords and tags but maybe I'll write an editorial some time.

Div.2 A : Binary search, B : Partial sum

Div.1 A : Binary search, B : Dijkstra, C : DP,Two pointers,queue, D : 2-sat, E: Hash, Segment tree, F : Divide and Conquer.

UPD7: You can find the editorial here.

Hi, Codeforces!

Welcome to the last Codeforces Round of 2014, Good Bye 2014! This round is very unusual; First, the round starts at December 30th, 18:00 MSK. Second, the round lasts for 2.5 hours. And lastly, the round will be division combined, which means Div1 contestants and Div2 contestants won't be separated.

The problems are prepared by me (.o.) and Seunghyun Jo (ainta). This is our second round at Codeforces. Because our first round caused(?) the Black Day, we hope this round won't cause any errors like before :D

Thanks to Won-seok Yoo(ainu7), who tested our round and gave us comments about the problemset.

We'd like to thank some people who were necessary to make this round: Maxim Akhmedov (Zlobober) gave us great help preparing the problems. Maria Belova (Delinur) translated problem statements in Russian. Mike Mirzayanov (MikeMirzayanov) made Codeforces and Polygon systems, which are really great. Let's give them an applause!

The score distribution will be posted just before the round starts, as usual.

We wish you all the best of luck. Happy New Year!

UPD (2014-12-30 17:33:21) The score for each problem is going to be 500-1000-1000-1500-2750-2750-3500. Thanks to Xellos for giving us some ideas.

UPD (2014-12-31 12:49:05) Round has finished, congratulations to the winners!

1. tourist
2. Petr
3. rng_58
4. HYPERHYPERHYPERCUBELOVER
5. subscriber
6. Merkurev
7. al13n
8. mmaxio
9. mexmans
10. GlebsHP

Also, thanks to Marcin_smu, who solved problem G after the contest for the first time.

UPD(2014-12-31 12:51:08) Editorial is published. Currently, only A-F is available, but I will add G as soon as possible. Sorry for the late editorial.

UPD(2015-01-02 21:30:44) I wrote the editorial of G. Sorry for the late update..

Note that schedule have been changed for a New Year contest Good Bye 2014. Round starts at December 30th, 18:00 MSK and lasts for 2 hours 30 minutes. It will also be division combined.

Wait for an announcement for further details. New Year is coming!

Soon you are lucky to participate in Codeforces Round #284, and problems have been prepared by Vitaly Gridnev (gridnevvvit), Ilya Los (IlyaLos), Danil Sagunov (danilka.pro).

We want to thank Max Akhmedov (Zlobober) for help with preparation of this round, Maria Belova (Delinur) for translation of statements and Mike Mirzayanov (MikeMirzayanov) for marvelous Codeforces and Polygon systems.

Scoring system will be dynamic. Problems will be arranged in ascending expected difficulty order.

Round finished, congratulations to winners!

Div1:

1. yeputons
2. rng_58
3. Endagorion
4. KADR
5. Egor
6. uwi
7. mmaxio
8. atetubou
9. RAVEman

Div2:

1. sorry_dreamoon
2. dreamoon_love_AA
3. dreamoon_fan

Editorial

Good luck!

Доброго времени суток, уважаемые пользователи Codeforces!

Хочу ещё раз обратить внимание всех потенциально заинтересованных участников на такое мероприятие как Открытая всероссийская олимпиада школьников. Напоминаю я не просто так, а по отличному поводу — сегодня там появились три новые задачи, а в ближайшие дни ожидаются ещё две. Задачи подготовлены жюри московских олимпиад, мы честно старались сделать их интересными и разнообразными.

Если кто-то пропустил начало олимпиады, то в этом нет ничего страшного, до конца ещё целый месяц, вполне достаточно, чтобы сдать все предложенные задачи. Время сдачи никак не влияет на положение в таблице. Лучшие X участников будут приглашены поучаствовать в очном финале, для которого задачи отбираются с ещё большей любовью и заботой, так что не упустите свой шанс.

Для тех, кто руководствуется более приземлёнными соображениями, чем качество задач, дополнительно сообщаю, что заключительный этап традиционно имеет первый уровень, а значит призеры и победители могут получить льготы при поступлении в вуз в соответствии с порядком приема в вузы.

Призеры отборочного этапа олимпиады никаких льгот не имеют — поступить не выходя из дома всё-таки не получится.

Более подробную информацию об олимпиаде вы можете найти по приведённой выше ссылке. Любые оставшиеся вопросы смело задавайте в комментариях.

P.S. Тех, кто будет в комментариях обсуждать решения задач, ждёт справедливое возмездие и отрицательная карма!

UPD: добавлены две новые задачи, больше задачи добавляться не будут.

UPD2: Почти наверное традиционного продления олимпиады не будет. Планируется пригласить порядка 400 участников. Обратите внимание, сейчас для попадания в топ-400 требуется набрать совсем немного баллов. Жюри рекомендует прочитать все задачи — почти в каждой имеются простые группы с немалым количеством баллов.

Hi, Codeforces.

We have put 2014 ACM-ICPC Xi'an Regional Contest, one of this year's Chinese regional contest in Codeforces Gym.

The 2014 ACM-ICPC Asia Xi‘an Regional Contest (2014) takes place on 25 Oct 2014 — 26 Oct 2014 in Xi'an, China. The problem set was prepared by Fudan University.

Standings are translated to English by matching their team names and their registration info on ICPC official website. For those schools which didn't register on ICPC official website, I have manually "translated" (in fact, Google and Copy & Paste) their school name to English. Inform me if you found any mistake.

Problem G has slightly looser time limit than onsite contest: alternative solutions run way slower on Codeforces, while model solution runs way faster.

Thank MikeMirzayanov and Fefer_Ivan for the Codeforces Gym platform!

Hi, Codeforces.

Today, on December 17 at 19:30 MSK regular, 283-rd Codeforces round will take place. Problems are authored by me, Mikhail Tikhomirov. Maxim Akhmedov (Zlobober) helped me with discussing and preparing the problemset, Maria Belova (Delinur) translated problem statements in English, and Georgy Chebanov (gchebanov), Alexander Mashrabov (map) and Niyaz Nigmatullin (niyaznigmatul) tested the round and helped us with finding bugs and mistakes; let's give them a round of applause!

The round will be for both divisions. The scoring is standard (not dynamic); score distribution is as follows:

Div. 1: 750-1250-1250-2000-2500

Div. 2: 500-1000-1750-2250-2250

This is going to be my fourth round at Codeforces. I really hope it will go as good as three before it. =) Wish you all the best of luck!

UPD: the round is over, thanks for participating!

Grats to the winners:

Div. 1:

1. SirShokoladina

2. Petr

3. rowdark

4. anta

5. Marcin_smu

6. Merkurev

7. qwer1561

8. Ra16bit

9. kuviman

10. Um_nik

Div. 2:

1. SergeyMelnikov

2. sepehr103

3. StarCuriosity

4. dotato

5. husheyn

Editorial is here ( UPD: now in English!).

The contest is in gym now.

The 2014 ACM-ICPC Asia Mudanjiang Regional Contest takes place on 11 Oct 2014 — 12 Oct 2014 in Mudanjiang, China. There are 11 problems in this contest. The problem set was prepared by Zhejiang Univesity. These problems also can be found at http://acm.zju.edu.cn (Problem 3819-3829).

The official results can be found at this page. Congratulations to Jilin Unversity to win the contest!

In the contest, problem A, C, D and F is written by Archon.JK, B is written by yxdb and navi, E and I is written by me(ZhouYuChen), G and J is written by zimpha, H is written by chnluyi, and K is written by prowindy. Bobgy, Flandre_Scarlet, fancy, NeverLand.Dai and -.- also tested or discussed the problems.

Thank MikeMirzayanov for helping us migrating the problems to Codeforces!

Any suggestions or feedback is welcome.

Hi,

Codeforces Round #282 will be held at 13th of December, 19:30 MSK. Please don't note anything since the time is the usual time of contests.

The round is prepared by FarbodY, Haghani and Me(matrix).

We'd like to thank Zlobober who helped us a LOT for preparing the problems, MikeMirzayanov for the Polygon and Codeforces platforms and Delinur for helping us in preparing statements and translating them.

Our special thanks goes to mruxim for testing the round.

The problems will be sorted according to the estimated order of difficulty according to our opinion but we strongly recommend you to read all of the problems.

As always the update regarding score distribution will be posted just before the round starts. :)

UPD: It was written that contest starts at 20:00 MSK. it was a mistake and is fixed now. The round starts at usual time 19:30 MSK.

UPD2: We also thank niyaznigmatul for testing our round.

UPD3: Score distribution:

Div1: 500-1000-1750-1750-2500

Div2: 500-1000-1500-2000-2750

As you might have noticed, the scores can now be multiples of 250 as well. Let's thank Codeforces team for adding this feature!

Good luck and Have fun!

UPD4: Congratulations to the winners of both divisions:

Div1:

1. tourist
2. winger
3. sankear
4. uwi
5. Egor

Div2:

1. Ginger88895
2. pwild
3. arthurpd
4. konmaj
5. ezkatka

The editorial for all problems except D and E Div1 are ready and can be found here. It'll be completed soon.

We thank you all for participating and hope you had a good time.

UPD5: The editorial is now complete and can be found here.