By MikeMirzayanov, 8 years ago, translation, In English,

Hi!

I regret to inform you that the Codeforces Beta Round #88 is rescheduled for September, 23 (Friday), 15:00 (UTC). The main reason lies in me — because of trip to TopCoder Open, I must leave Saratov, and I can't make the round being in a train, in the middle ofendless Russian steppes.

I hope that the new schedule will be comfortable for some of you, and other will try to adjust plans to the schedule.

See you at the round
MikeMirzayanov

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By dolphinigle, 8 years ago, In English,
Welcome to Codeforces Beta Round #87!

The mysterious author of today's match (which turns out to be me) have prepared seven problems for you (five in each division). Since I can't spoil you any of the problems yet, for now I can safely say that I like all of today's problems. The problem statements are wonderfully crafted (and translated) with the help of both RAD and Delinur and they are now very easy to read. My hope is that you will like them as well :).

There will be .png images in some problems, so make sure your browser can support them. You may want to check if you can see the image in the Time to Raid Cowavans problem (authored by Alex_KPR).

And also a warm thanks to it4.kp for testing the problems (for the fourth fifth time I might add - he tested 4 of my SRMs already :) ) together with RAD, and to MikeMirzayanov and the entire Codeforces team for the great system and this opportunity! Indeed it is through this website that I receive my current internship offer :).

So from Kraków I wish everyone and the Codeforces' server good luck and stay strong :).

===

The match has ended! Thank you for participating - I enjoyed it :). Here's the Editorial for this match.

The top three of the Division1 solves all five problems! They are followed by al13n and kcm1700 who solved 4 problems in approximately one hour. Congratulations!

Division 1:
2. Petr
3. Egor
4. al13n

In division 2, we have exactly 5 persons who solved all 5 problems, the fastest solved all five problems within 1 hour 4 minutes! Congratulations!

Division 2:
1. kyrka
3. Skird
4. ts10

I hope I can author other set next time here. Till we meet again.

Final rants

If I could turn back time, I would change the following:
1) Swap problem D1-D and D1-E
2) modulo 1,000,003 becomes modulo 1,000,000,007
3) N^2 solutions means N >= 4,000
4) Time limit should be made for Java, not Python...

Lesson learned. And the N^3 solutions which pass turn out to be beautiful after I see them (all of them implements different algorithm after I read them more carefully). Not to mention there's 3 passing N^2 solutions. Okay, I'm content now :) - apologies for my rants yesterday.

=== stale rants below ===

Oh, after the coding phase, you may want to visit this post again.

Guess what? It's starting! Rawr! I'm honored that it broke the maximum number of participants so far - thank you guys :).
Link to standings:

Now that the match is over...
I owe division 2 apologies for making D2-D too easy. Sorry - I didn't see that coming.
Anyway, while you're busy waiting for scores to pop up in your respective division summary, here you go! Editorial for this match.

I don't know, I hope all N^3 solutions in D fail. Otherwise I owe you guys another apology. I'll be more evil with constraints next time :)
Okay, so a big apology from me for letting a N^3 solutions to pass D1-D. It didn't cross my mind that N^3 = 2000^3 would run under 2 seconds. I'll make sure not to make things like this happen again in my matches :( - 5000 here I come.

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By _jte_, 8 years ago, translation, In English,

Hi all, 


Today we would like to invite you to take part in round #86. Round is prepared by Andrew Malevich (aka Kenny_HORROR) and me, Taras Brzezinsky. We are students of Belarusian State University. We would like to thank  MikeMirzayanov ,  it4.kp , RAD , Gerald и Fefer_Ivan for helping and advice in preparing round and  Delinur for translation.

While participating, you will get known with boy Peter and remember some of his school days to help him to solve some problems

The points for the problems in Div 1 & 2 will be: 500-1000-1500-2000-2500.

New service "Virtual contest" will be unavailable during the round due to possible instability.

Good luck to everyone!

UPD

The contest is finished, ratings are updated. 
Congrats to winners:
DIV1:
2) KADR
3) yaro
5) Egor

DIV2: 
4) lxn

Editorial is currently available, the whole problem set analysis will be added in few hours.

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By MikeMirzayanov, 8 years ago, translation, In English,
Hi everybody!

As some of you have already noticed, we are introducing the innovation &mdash a virtual contest system. I guess this term was invented as far back as in 2002, as we were working on the site http://acm.sgu.ru/. Besides we were the first ones to come up with and carry out the interesting idea: enable the users to run the past contests in a special mode that would imitate a real competition. It feels just like a real contest with real contestants competing alongside with the participant who writes a virtual contest.

The idea was a success and it was picked up by some online judges. Although frankly speaking, those ideas haven't been carried out by the many.

And now it's time to introduce the virtual contest system to Codeforces! Of course, the original Codeforces rules aren't easily converted to virtual form. That's why all past Codeforces contests will be available as virtual contests by ACM-ICPC rules. In light of oncoming ACM-ICPC subregional and regional contests it can be regarded as yet another opportunity to train.

Virtual contests are available to individuals as well as to teams. If you participate as a team, please make sure that the registered team represents all your team members and nobody else. If it is not the case, change it. So far there's only one contest available for alpha-testing: it's Codeforces Beta Round #76 (Div. 2 Only), but you won't have to wait much - soon all contests will be available in this mode. Now all the past contests are available as virtual contests.

When you take part in virtual contests please follow those simple rules:

  • don't participate if you've already seen the tasks;
  • don't participate if you only want to commit one problem or if you don't want/can't participate in the whole contest;
  • during the contest don't read tutorials, don't use somebody else's code, don't talk to other people;
  • try to make it an efficient and enjoyable training!

I expect some of you to write the offered contest virtually and share your impressions. For example, JKeeJ1e30 has already participated!

I hope you like the new opportunities. We'll add something, too, to give the system final flourish, but in any way we're waiting for your commentaries rich in interesting ideas and suggestions.

MikeMirzayanov and the Codeforces team

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By Seyaua, 8 years ago, In English,
Hi to everybody from sunny Petrozavodsk!

Today me and my brother sdya prepared a few interesting problems for you. Because of very tight schedule in Petrozavodsk training camp, that includes rafting and watching anime all night long, we didn't have time to write long problem statements. So enjoy unambiguous short statements and you are welcome to invent some legends for them on your own.

Good luck and have fun!

Contest is over! Congratulations to winners!

Division 1:
  1. dolphinigle
  2. ilyakor
  3. marek.cygan
Division 2:
  1. wuzhengkai
  2. jayi
  3. superpear
Editorial.

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By witua, 8 years ago, translation, In English,
Hello!

Welcome to Codeforces Beta Round #84I am Vitaliy Herasimov (witua) and I am an author of today's problems. Thanks to Artem Rakhov (RAD) and Pavel Kuznetsov (it4.kpfor the help and advices in preparing of the rounds, Maria Belova (Delinur) for the statements translation.

Good luck!

Contest is over! Congratulation to winners!

Division 1:

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By Atef, 8 years ago, In English,
Hi all,

Today we would like to invite you to take part in round #83 inspired by the ACM practice sessions last year when Dima was visiting the German University in Cairo (GUC).

We have composed the problemset about life in Egypt and the GUC. Hope you will like it :)

The points for the problems in Div 1 & 2 will be: 500-1000-1500-2000-2500.

The writers of the problems are Dima and myself.

We would like to thank RADConnectorit4.kpDelinurand MikeMirzayanovwho greatly helped in preparing this contest.

We wish you a pleasant, educational and successful contest!

The editorial is under construction.

Good luck to everyone!

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By Ripatti, 8 years ago, translation, In English,

Good evening.

Today's round is mine, as the previous one. This round will be for participants of the second division. Participants of the first division can take part in the round out of competition.

RADConnectorit4.kp and MikeMirzayanov helped me to prepare this round. Delinur translated statements into English.

Contest will be in the good old tradition of Codeforces. No any innovations, pretty short and clear statements.

Points for problems are standard: 500-1000-1500-2000-2500.

Good luck everyone!


UPD. Round was ended, ratings was updated.

Winners:

1. tsundere

2. jte

3. abacadaea

4. ltaravilse

5. Billy_Herrington

Editorial.

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By Ripatti, 8 years ago, translation, In English,

Hello everyone!

I am the author of problems of today round. RADConnectorit4.kp helped me to prepere this contest. Delinur thanslated statements into english.

It will be a thematic contest. And the theme is Disgaea.

Is it possible to survive artef damage that is written by nine-digit number?
Of course, if amount of your health points is ten-digit number.
fans about Disgaea

Disgaea: Hour of Darkness is tactical RPG video game for consoles Playstation 2, PSP и Nintendo DS. So, get acquainted:

Etna, Laharl and Flonne - main characters of the game

The problems involves some aspects of the game mechanics. They are adapted for problems, therefore a bit different from original ones. Please use statements as formal documents.

Some problems have animated pictures. Please ensure that your browser supperts formats APNG or GIF.

Problem points will be standard for contests of Codeforces:
500-1000-1500-2000-2500.

Good luck!

UPD. The contest ended and ratings was recalculated.
:Winners:
1. KADR
2. neal
3. cerealguy
4. ivan.popelyshev
5. tourist

Editorial.

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Announcement of Codeforces Beta Round #81
Announcement of Codeforces Beta Round #81
 
 
 
 
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By Alex_KPR, 8 years ago, translation, In English,

Hi all!

Now it's time for 80th Codeforces Beta Round.

The authors of the contest are: Alex_KPRwingerRADConnectorit4.kp. I hope all problems will be interesting for you and not extremely hard. ;)

Today is Connector's birthday — so, let's congratulate him together!

Good luck and have fun!
_____________________________________

Thank you for your action! =)

Top 10 participants in the first division are:

Place
Who
1
 SergeiRogulenko
2
 hos.lyric
3
 Romka
4
 neal
5
 sdya
6
 KADR
7
 ftiasch
8
 niyaznigmatul
9
 dolphinigle
10
 AleX

There are only two participants who beat problem E: the winner of the contest SergeiRogulenko and MBabin who gets 76th place.

Top 3 participants in the second division are:

Place
Who
1
 anrieff
2
 zplinti1
3
 Efgen

Congratulations and good luck at the next time!

Official tutorial will be added later. But AlexanderBolshakov already wrote the tutorial about most of problems.

Problems were translated by Delinur.
_____________________________________

Tutorial is here.

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