By Alexander, 12 years ago, translation, In English

Hello World.

 The next Codeforces round is prepared by me. This is my debut in arranging contests. I invite everyone to participate in the second division. I hope that all goes well. I wish you have a nice time and be able to improve your skills in programming.

 Thanks to Artem Rakhov (RAD), and Mike Mirzayanov (MikeMirzayanov) for preparation of the round and for motivation.

 Good luck and high rating!

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By Nickolas, 12 years ago, translation, In English

TCO11 - is the second (and hopefully not the last) finals I've visited as a blogger. I hope that not everybody here followed the official blog, and thus my story of this trip will be read as an original art work :-)

Day -1. Arrival

I arrived one day earlier than most of the finalists, on Friday evening local time. How does one do this? Long story short, you just don't rely on Barbara's choice, and (when filling travel info) write something like "I like this flight, and I'm in SWISS mileage program, and I absolutely love Zürich". Disclaimer: if everybody uses this hack, it might stop working, so beware.

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By AlexSkidanov, 12 years ago, translation, In English

Last time I mentioned, that one of the winners of the 'best event for participants' competition was a girl, who offered participants to take pictures based on tasks like "take a picture of yourself and <description of other person> doing <description of setting>". Even though that is a really awesome event, very few people were interested in it, which was very sad.

Every person had a different set of 10 tasks, the winner was the one who had more pictures, and the tiebreaker was an additional picture, having most people in the air jumping on the beach.
At the end I had only 9 pictures + a tiebreaker with 8 people in the air, while MikhaelOK had 10 pics without a tiebreaker. The person for the 10th picture already agreed to help me, but organizers told me that I do not qualify for the prize of 2012 trip (since I am one of the sponsors), and I just gave up.

My tasks were:
1. Take a picture with a TopCoder Admin with TCO logo in the background. Everybody had that one, and it was very easy.

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By AlexSkidanov, 12 years ago, translation, In English

TopCoder Open 2011 keeps going.

Yesterday we were supposed to hold a poker tournament with a grand prize MacBook Air. There were a lot of people willing to participate, which forced us to split the tournament into two elimination rounds and one final. Out of 16 people who registered for the tournament, 8 were russian-speaking, and all of them appeared to be in the same elimination round. Petr and MikhaelOK advanced from that round, while 7ania7 and theycallhimtom advanced from another one, which was non-russian-speaking. Unfortunately I don't have any pictures of the elimination rounds, however, we played more poker that day, in the same place, so this picture gives you pretty good understanding of how it looked like (during the elimination round it was a little bit more crowded though):

Last time I didn't publish any pictures of a hotel, except one view out of the window. The hotel is called The Westin Diplomat.

It is located in a Hollywood city. The city is in 20 minutes of driving from Miami, however it looks like a small village with a lot of palms. The hotel looks weird in such a setting, since essentially it is 36-storey skyscraper. It is located right next to the Ocean shore, such that the moment you leave the hotel, you find yourself on the beach.

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By AlexSkidanov, 12 years ago, translation, In English

Today I and Eric, CEO of MemSQL, went to Florida, to the Hollywood city, to visit TopCoder Open 2011, which we sponsor. Intel and Facebook are two other sponsors.
We left San Francisco at 8 AM. In SFO we saw Petr. That made us believe, that he moved to the Valley, which turned out not to be the case.
First thing you see in the hotel is TopCoder banner. Do you know the company, which is listed third in the sponsors list? :о

We went to a Ballroom, where we needed to install our booth. Intel has entire corner in the ballroom, while we and Facebook have small table and a screen. This is how it looks like:

When booth had been installed, we checked in to the room. According to what I heard from competitors, TopCoder provided them with rooms with no ocean view. Since we didn't have room provided by topcoder, for ourselves we got the one with the view.

In 2008, when I was visiting all the programming events, I was taking pictures of all the TopCoders, and other people, who were related to the community, with a stuffed pig. Some of those pictures you can find in my blog here. This time three more people didn't manage to avoid my camera. One of them is Ivan Metelsky, who is working on topcoder SRMs, and also is a judge on the TCO:

Two other are Artem Rakhov and Mike Mirzayanov, who are well known on this website :)

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By MikeMirzayanov, 12 years ago, translation, In English


Yesterday I got to the Hollywood (not in California, but in Florida). Then I came out from airport, I felt hot, humid air. Not forgotten feeling from the ACM-ICPC finals tried to fool my brain, that I was not leaving Florida.

I was flying with Misha Kever (which the handle here?). Artem Rakhov (RAD) appeared when I was asleep. It seems that he has arrived together with Sergey Rogulenko(SergeyRogulenko).

It turned out that the rainy season is not over. So here “cloudy, possible rain." I did not like the ocean — very warm, quite without the waves, it is necessary to overcome large distance to swim on depth.

By the way, I’m in the room #1760. It will be good to see in comments rooms of other finalists.

As they say, to be continued ...


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By Gerald, 12 years ago, translation, In English

Hello everybody! My name is Gerald Agapov. I study at Saratov State University. Today I present you the set of, I hope interesting, problems. Good luck to all!

And also a warm thanks RAD,  MikeMirzayanov and the entire Codeforces team for the great system and this opportunity! (с) dolphinigle


The match has ended. Thank you for paticipating!

Top 5 Coders:
5. kelvin

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Announcement of Codeforces Beta Round 88
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By MikeMirzayanov, 12 years ago, translation, In English


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

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By dolphinigle, 12 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 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_, 12 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 , , 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!


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

4) lxn

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

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