Codeforces round #305 is gonna take place soon and I'm the writer.

After my previous contest that many people think it was a hard contest, I prepared an easy contest to cheer you up!

I want to thank Haghani for testing this round, Zlobober for help me prepare this round and his great advises, Delinur for translating problem statements into Russian, mruxim and Yasser Ahmadi Phoulady (Rasta) for their advises and ideas, HosseinYousefi for helping me choose legends and graphics and MikeMirzayanov for great Codeforces and Polygon platform and guys from Physics Olympiad that kept disturbing me while preparing this round.

This is my second official round and I hope you enjoy it.

The main character of this round is gonna be Mike (I didn't say MikeMirzayanov :D).

Also you'll meet Xaniar and Abol.

I wish you all Successful hacks and Accepted solutions and high ratings.

Scoring will be posted soon.

GL & HF!

UPD: Scoring is:

• Div.2: 500-1000-1750-2000-2750
• Div.1: 750-1000-1750-1750-2500

UPD2: Due to technical reasons we moved the round by 5 minutes.

UPD3: Contest has just ended. You can find the editorial here.

UPD4: System testing is done.

Congratulations to the winners, specially dreamoon_love_AA that got to his goal !

Div.1 winners:

1. dreamoon_love_AA
2. HYPERHYPERHYPERCUBELOVER
3. jqdai0815
4. YuukaKazami
5. subscriber

Div.2 winners:

1. fromWork
2. IloveGoodness
3. norge
4. rumman_sust
5. williamzpf

See you in the next rounds.

This is my first attempt at writing something useful, so your suggestions are welcome.

Most participants of programming contests are familiar with segment trees to some degree, especially having read this articles http://codeforces.com/blog/entry/15890, http://e-maxx.ru/algo/segment_tree (Russian only). If you're not — don't go there yet. I advise to read them after this article for the sake of examples, and to compare implementations and choose the one you like more (will be kinda obvious).

Segment tree with single element modifications

Let's start with a brief explanation of segment trees. They are used when we have an array, perform some changes and queries on continuous segments. In the first example we'll consider 2 operations:

1. modify one element in the array;
2. find the sum of elements on some segment.

I've just discovered this question on Quora: What is the story behind your username at CodeForces?. I guess it'd be pretty interesting to hear stories from top participants. For instance, my handle's history is already described there.

This blog is dedicated to everyone who don't have Quora account, so you can share your histories and comments here.

I personally would love to hear stories from tourist, rng_58 and YuukaKazami from current top-10.

Hi everyone!

I am pleased to announce that Codeforces Round #304 (Div.2), of which I am the author, will take place today. This will be my first round, so I hope that it will be cool and interesting. Traditionally Div.1 participants can take part out of the competition.

I want to thank znirzej, Dakurels and Zlobober for help with preparing the problems, thank Delinur for translating the problems, and thank to MikeMirzayanov and all who created polygon for this great system.

I wish you all good luck!

UPD Scoring will be 500-1000-1250-1500-2250.

UPD editorial

UPD Congratulations for winners in div.2:

1. phoenix__jpn
2. Hujishiro_otone
3. lzw4896s
4. jinzhao
5. jabbawookiees

And in div.1:

1. ngfam_kongu
2. uwi
3. anta
4. W4yneb0t

Hello!

Only a few hours before the start of ACM-ICPC World Finals 2015!

The ACM ICPC is considered as the "Olympics of Programming Competitions". It is quite simply, the oldest, largest, and most prestigious programming contest in the world.

The ACM-ICPC (Association for Computing Machinery — International Collegiate Programming Contest) is a multi-tier, team-based, programming competition. Headquartered at Baylor University, Texas, it operates according to the rules and regulations formulated by the ACM. The contest participants come from over 2,500 universities that are spread across 100+ countries and six continents.

This year the best 128 teams in the world will meet face to face in Marrakech on World Finals. Video coverage will start on 09:00 (UTC), and the contest will start on 10:00 (UTC).

• current standings (currently there are practice session results there), alternative standings table by Ahmed Aly
• video on youtube
• text coverage on tumblr
• offcial photos
• twitch channel 1, twitch channel 2
• Petr Mitrichev's blog

Good luck to all the teams!

UPD Added link to the text coverage on tumblr.

Hello everyone!

I am glad to announce that soon will Codeforces Round #303 for Div.2 paricipants, the author of which I am. Traditionally Div.1 participants can take part out of the competition.

This is my first round, and I hope that it will be interesting.

Round wouldn't take place without the help of the Codeforces team! Great thanks to Zlobober for helping me preparing the round and Delinur for translation. Special thanks to everyone who puts his effort into the creation and maintenance of Codeforces and Polygon systems.

Score distribution will be announce later.

Good luck and inspiration!

UPD Score distribution will be — 500-1000-1750-1750-2500.

UPD Congratulations for winners in Div.2:

1. Bell-sama
2. anko
3. BobDylan
4. Gusheng
5. Diguised
6. imyyimdog

And in Div.1:

1. ngfam_kongu
2. Laakeri
3. Um_nik
4. KrK

UPD Link for editorial.

Hi everybody from the ICPC Live team (elizarov, pashka, niyaznigmatul, Egor, lperovskaya and me).

We want to inform you, that broadcast of the World Finals will take place on Wednesday, 20th of May.

The broadcast will be on the two websites (youtube and twitch). The links will be posted tomorrow, but you could subscribe to our channel.

We will have the following schedule:

• 12:00 — broadcast starts
• 13:00-18:00 — contest
• 19:00 — closing ceremony

Don't forget to subscribe on our channels on youtube and on twitch: icpclive1 and icpclive2.

While you wait, on Tuesday, May 19 Dress rehearsal will take place. The broadcast will be available on the youtube channel ICPC Live and on the twitch channel ICPC Live. The idea of this broadcast is to check, if everything is fine, so, please, be nice and report availability or performance issues. We can't guarantee the good broadcast.

Regards, Team ICPC Live

UPD: Read live ICPC Finals text broadcast. http://icpcnews.tumblr.com/post/119424970944/world-finals-live

UPD2: youtube

UPD3: twitch, main screen, twitch, split screen

UPD4: Thanks to alexyz for the link: multitwitch

The last but not the least interesting team is ITMO University's team 1.

ITMO has most championship titles, 5, out of 19 finals they participated in. They've got 10 Gold medals total, 1 Silver and 1 Bronze.

This year team consist of 2 Bronze Medalist from 2014, Borys and Artem, and World Champion from 2013, Gennady. Team is on first place in OpenCup Standings, won numerous contest this year and universally regarded as favorite to win World Finals, are coached by Andrey Stankevich.

Gennady Korotkevich (TC: 3794, CF: 3407) is one of the most honored coders ever. ACM ICPC Champion in 2013, TCO Winner in 2014, GCJ Winner in 2014, IOI Gold Medalist for a whooping 6 years (2007-2012), that's in addition to SIlver (2006) and many more achievements like Facebook Hacker Cup wins.

Borys Minaiev (TC: 2760, CF: 2776) won Bronze in last year Finals, was TopCoder Open Semifinalist in 2014, Facebook Hacker Cup Finalsit in 2015 and got 3rd place in Kotlin Challenge in 2014.

Artem Vasilyev (TC: 2612, CF: 2545) got World Finals Bronze in 2014 and was KROK Finalist in 2013.

It would be really unlikely for ITMO not to win Gold Medals, I have their chances at 99%. I think their chances to win is about 75%.

Create your own ICPC cheering party, join one in you city or just follow ACM ICPC World Finals Live

This year my alma mater is represented by team Moscow SU Tapirs.

Moscow State University has a long history at World Finals. 19 appearences, 4 Gold medals (all of them — 2nd places), 1 Silver and 7 Bronzes. Moscow SU is also 2 times champions of Europe.

Tapirs team came 2nd last year in Yekaterinburg in intense battle with St. Petersburg State University. In NEERC 2014 they came second as well, while losing to ITMO University team only on penalty time. Moscow SU is currently 3rd in OpenCup standings with one stage win. They had bested ITMO team on 2 more stages. Anton Pankratiev is team coach.

Gleb Evstropov (TC: 2405, CF: GlebsHP 2622) got 3rd in this year Facebook Hacker Cup. He also won Silver medal in IOI 2010 and was Russian Code Cup finalist last year.

Victor Omelyanenko (TC: 2531, CF: TeaPot 2687) got 2nd place on ACM ICPC World Finals last year with Gleb and Mikhail.

Mikhail Pyaderkin (TC: 2428, CF: meshanya 2550) won IOI Gold in 2010 as well as placed 2nd in Vekua Cup personal contest in 2012.

This team got only stronger since last year. Their chance to win Gold are at least 80%, while they had shoy at Championship as well, with about 15% chance.

Last team to look at will be ITMO University team.

Create your own ICPC cheering party, join one in you city or just follow ACM ICPC World Finals Live

Today let’s talk about The University of Tokyo team !#$%&()*+-./:;<=>?@[]^_`{|}~. University of Tokyo has long history of World Finals participations, this would be 13th time. They won one Gold, one Silver and 2 Bronzes, and 2 members of this year team won Gold in 2013.

They won regional contests in Tokyo and Kuala Lumpur, only team in Asia this year with such achievement. Team is currently on 17th place in OpenCup standings, although they skipped several stages and not always had optimal line-up. Tomoyuki Kaneko coaching them.

Kensuke Imanishi (TC: 2625, CF: wrong 2298) won 2 Silver medals in IOI (2010 and 2011) and was GCJ Finalist in 2013, that's beside his Gold in ACM ICPC Finals.

Shogo Murai (TC: 3017, CF: semiexp 2507) has 3 IOI Golds (2010-2012) and target on TopCoder to boot.

Makoto Soejima (TC: 3468, CF: rng_58 2849) is really a legend. He is one of only 4 people to win both GCJ (2011) and TCO (2010, 2011) and currently is TopCoder admin. Beside that he has Silver in IOI (2008, 2009) and Gold in World Finals.

While this team has really strong line up it's results are inconsistent. I'd give them 70% for Gold and about 5% to win.

Tomorrow we will look at team from my alma mater, Moscow State University.

Create your own ICPC cheering party, join one in you city or just follow ACM ICPC World Finals Live