Hi everybody!

These days Moscow is conducting the 2nd International Olympiad of Metropolises that is an international competition for high school students from biggest cities and capitals all around the world. One of the disciplines of the competition is informatics. Rounds of the competition were prepared by the jury members invited from St. Petersburg, Minsk, Almaty and Moscow olympiad scientific committee which you may know by Moscow team Olympiad, Open Olympiad in Informatics and Moscow Olympiad for young students (rounds 327, 342, 345, 376, 401).

We are very grateful to MikeMirzayanov for Polygon system that made it possible to conveniently hold a simultaneous statement translation process into lots of languages. As a good friends of Codeforces platform, we conduct a parallel rated Div. 1 + Div. 2 round on the competition problemset.

Round will happen on September 6th at 12:55 UTC and it will last for two hours. There will be 5 problems for each division, scoring will be announced later.

Scientific Committee of the olympiad consists of: andrewzta, GlebsHP, Endagorion, meshanya, Chmel_Tolstiy, Zlobober, Helen Andreeva and Bakhyt Matkarymov. Problems were prepared by timgaripov, mingaleg, halin.george, vintage_Vlad_Makeev, malcolm, LHiC coordinated by your humble servant.

Codeforces coordinator KAN helped us to choose problems for a round.

Good luck and high ratings for everybody!

PS We kindly ask everybody who knows problems of an on-site event not to participate in a round and not to discuss them in public, as this may be a subject for disqualification.

Congratulations to the winners!

In div. 1 they are:

1. Um_nik
2. fateice
3. KADR
4. dotorya
5. FallDream

In div. 2 they are:

1. jiangIy
2. xolm
3. YxqK
4. lixolas
5. Rawnd

The analysis is published. Thanks to all for participating!

Hello Codeforces!

On September 05, 18:05 MSK Educational Codeforces Round 28 will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

The round will be unrated for all users and will be held on extented ACM ICPC rules. After the end of the contest you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 6 problems and 2 hours to solve them.

The problems were prepared by Mikhail awoo Piklyaev, Vladimir vovuh Petrov and me.

Good luck to all participants!

UPD. Editorial can be found here.

Congratulations to the winners:

Congratulations to the best hackers:

169 successful hacks and 113 unsuccessful hacks were made in total!

And finally people who were the first to solve each problem:

Hi!

I'm honored to invite you to Codeforces Round #432, it will be held on 4th September 14:35 UTC. There will be 5 problems for each division, as usual, you have 2:30 to solve the problems. The contest was prepared by Lewin Lewin Gan, Artsem Arterm Zhuk and me.

The IndiaHacks Final Round will be held on 3rd September 12:30. Finalist must not discuss the problems after their contest.

The stories of my problems will be about Arpa, although in one problem you'll see Mojtaba moji FayazBakhsh, my great teacher.

I'd like to thank Lewin, Artsem and myself (:P) at first, then Konstantin zemen Semenov and WHITE2302 for testing the problems, Nikolay KAN Kalinin for helping us in moving the contest to codeforces and Mike MikeMirzayanov Mirzayanov for the great Codeforces and Polygon platforms.

The scoring distribution will be announced later.

Obviously, if you are interested in if the round is rated or not, ask in comments and get a lot of down votes.

UPD. There will be 5 problems for div.2 and 6 problems for div.1.

UPD2. Scoring Distribution: div.1: 500-1000-1250-1750-2000-2500, div.2: 500-1000-1500-2000-2500.

UPD3. Editorial is partially ready. I'll complete it soon.

Congratulations to winners:

Div.1:

1 . BaconLi

2 . dreamoon_love_AA

3 . sd0061

4 . W4yneb0t

5 . Um_nik

Div.2:

1 . miaom

2 . fzzzq2002

3 . lzy960601

4 . Lucas97 and Szymanski_w (WoW !!)

Official results

Hi Codeforces!

It's our pleasure to announce the 10th edition of Bubble Cup. Bubble Cup is a programing competition organized by Microsoft Development Center Serbia (MDCS), and will be held this weekend. Contest will take place on Saturday, 2nd of September at 09:30 UTC, in Belgrade, Serbia. Live results will be available on the official Bubble Cup website (results will be frozen during the last hour of the competition). Winners will be announced at the closing ceremony.

Just like the two previous editions, this final will be followed by an online mirror competition on Codeforces. Mirror will take place on Sunday, 3rd of September at 10:00 UTC. Contest will last for 5 hours and ACM ICPC rules will be applied. It will be a competition for teams of 1-3 members. There will be at least eight problems.

We kindly ask participants of the onsite final to hold off discussing problems publicly until the mirror is over.

Contest was mainly prepared by employees of MDCS. We give our thanks to Nikolay Kalinin (KAN) for the round coordination, Mike Mirzayanov (MikeMirzayanov) and the team behind Codeforces and Polygon platforms. Special thanks goes to knightL for helping out with problem testing.

The contest will be unrated. The reason for this is because rules of this contest are not common for Codeforces. Also, it is only a mirror of an onsite competition.

Editorial will be available in the booklets section on the Bubble Cup website a few hours after the online mirror ends.

EDIT:
Here you can find mirror contests from the previous two finals:
Bubble Cup 8 — Finals [Online Mirror]
Bubble Cup 9 — Finals [Online Mirror]

EDIT #2:
The contest has started. You can see the live results on the Bubble Cup website.

EDIT #3:
Here are the results of the onsite finals.

The top three winning teams of the online mirror contest:
1. tourist, VArtem
2. zigui, molamola., dotorya
3. Um_nik, Kronecker
Complete rankings are listed on this link.

Congrats to all winners!

You can find contest editorial here.

EDIT #4:
Thank you for your comments. While our official and ainta's solution matched on the test cases provided we found out from the comments here that there are some edge cases we didn't handle correctly and don't know how to handle properly given the constraints. Because of that we decided to remove the problem from the set and reset all penalties people received from the incorrect submissions. Sincere apologies to everyone affected by this.

Hi!

I’d like to invite you to Codeforces Round #431 which takes place at 16:35 MSK on 1 September. Please note that the timing is again unusual.

One of the problems is created by adedalic and KAN, while the others are authored by me. This is my second round here, and it couldn’t have been realized without efforts of: AlexFetisov, ifsmirnov, Tommyr7, winger and wu_qing who tested the problems; KAN who appears to be a meticulous guide throughout the preparation process; and MikeMirzayanov with the supercalifragilisticexpialidocious Codeforces and Polygon platforms — my deep gratitude to you!

Both divisions are welcomed as rated contestants and will have five problems to solve in two hours. The scoring will be announced later.

Once upon a time, in a virtual galaxy far, far away, there was a lovely young singer by the name of Hatsune Miku. One lovely day, Miku got a job as a vocalist in Vocaloid, and that was very exciting. People said, “Oh, Miku, you sing so accurately! And so emotive, too!” Soon everyone was talking about Miku, and there were songs and paintings and even live concerts for, and with, Miku. Miku liked that.

And you, are to start a journey following the emotions in Miku’s voice. Oh, by the way, a late Happy Birthday to her — August 31 is (was) her tenth anniversary.

For the world you live in, thank you.

See you then, and wish everyone few bugs and fair ratings.

UPD 1 Scoring will be:

• 500-1000-1500-2000-2500 for Division 2;
• 500-1000-1750-1750-2500 for Division 1.

UPD 2 System test is done. Congratulations to the winners!

Division 1

1. dotorya
2. Reyna
3. SkyDec
4. V--o_o--V
5. ko_osaga

Division 2

1. lmmortalCO (solved all problems!)
2. ltg2030
3. FoolMike
4. HatsuneMiku
5. MisakaKuma

Also, thanks to all who participated! Nicely done!

Check out the editorial with hints!

UPD 3 Complete tutorials and behind-the-scene fragments are out. Problem packages may be published soon, stay tuned!

Hi everybody!

On August 29, в 18:05 MSK Codeforces Round #430 (Div. 2) will be held. As usual, Div.1 participants can join out of competition.

The problems are prepared by me Glebodin and Ilya Ilua Maximov. Many thanks to Alexey Perforator Ripinen for help in preparations of the round. Great thanks to Alexey Livace Ilyukhov, Ildar 300iq Gainullin, Daniil qoo2p5 Nikolenko for testing the round, Nikolay KAN Kalinin for helping us preparing the round, Maxim HellKitsune Finutin and Ivan BledDest Androsov for testing this round and Mike MikeMirzayanov Mirzayanov for the Codeforces and Polygon systems.

The scoring is : 500 — 1000 — 1500 — 2000 — 2500

Congratulations to the winners:

Div. 1:

uwi

vintage_Vlad_Makeev

natsugiri

kmjp

victoragnez

Div. 2:

fatego

sufficiently_large_boss

qscqesze6

white_flag

Panole2333330

Editorial : http://mirror.codeforces.com/blog/entry/54179

For the last 6 years the world titles have been won only by St Petersburg teams – ITMO and St. Petersburg State University – both universities will bring their top teams to 2nd Hello Barcelona Programming Bootcamp in collaboration with Moscow Workshops ACM ICPC

The event runs from Sept 27 to Oct 5 – but how to get the most out of the camp? "I think there is no universal solution for "get the most out of a camp" – everyone should find their own path, but the general guideline will be: communicate with other participants as much as you can, make sure you do upsolving (at least some), keep track of how much you sleep," said Gleb Evstropov, coach and coordinator of the programming committee.

Sleeping could be somewhat challenging with all the famous Russian teams coming, which includes ITMO, St. Petersburg State University, MIPT, Ural Federal University, Tomsk, Novosibirsk, Saratov, Samara and Perm, as well as the rest of the world’s top universities such as USA’s highest placing team, Central Florida, along with Canada’s Waterloo, high-scoring Asian teams from Hangzhou Dianzi and Singapore, and Tokyo University, as well as Stockholm’s KTH among dozens of others – so far teams from 30 countries have signed up.

The event’s Gold sponsor is Sberbank, the biggest commercial and investment bank of Eastern Europe and Russia, with over 170 years of history. Thanks to their support we expect that the top participants will be awarded valuable prizes, alongside high-profile internships and job opportunities.

Hi, Codeforces!

AIM Tech Codeforces Round 4 will take place on August 24, at 19:35 MSK.

The round is prepared by AIM Tech employees: malcolm, Kostroma, Edvard, yarrr, zemen, gchebanov, VadymKa, zloyplace35, ValenKof, riadwaw and zeliboba.

Round will take place during Petrozavodsk Summer Camp, which is sponsored by our company.

Thanks to Mike Mirzayanov(MikeMirzayanov) for brilliant platforms Polygon and Codeforces and problem coordinator Nikolay Kalinin (KAN). Many thanks to qwerty787788, Zlobober, ifsmirnov and AlexFetisov for round testing!

Our company specialises in proprietary trading, the key concepts in our work are big data, low latency and high frequency. Our team mainly consists of graduates from the Moscow State University (MSU) and Moscow Institute of Physics and Technology (MIPT). You could read more on our website aimtech.com.

Participants of both divisions will be given 5 problems and 2.5 hours to solve them.

Problems C-D-E in the first division have almost the same difficulty, so we advise read all of them.

Scoring in the second division 500-1000-1500-2000-3000, in the first division 500-1000-1750-2250-2250.

We wish you good luck and high frequency rating!

Congratulations to winners!

Div. 1:

yosupo

SpyCheese

DEGwer

W4yneb0t

Um_nik

Div. 2:

epicure

bazsi700

Shavkat_Aminov

Tian.Xie

madn

Strikeskids

Hello Codeforces!

On August 21, 18:05 MSK Educational Codeforces Round 27 will start.

Series of Educational Rounds continue being held as Harbour.Space University initiative! You can read the details about the cooperation between Harbour.Space University and Codeforces in the blog post.

The round will be unrated for all users and will be held on extented ACM ICPC rules. After the end of the contest you will have one day to hack any solution you want. You will have access to copy any solution and test it locally.

You will be given 7 problems and 2 hours to solve them.

The problems were prepared by Ivan BledDest Androsov, Vladimir vovuh Petrov, Mike MikeMirzayanov Mirzayanov and me.

Good luck to all participants!

Harbour.Space also has a word for you:

We are delighted to welcome the 2017 ACM-ICPC World Champions, ITMO, to our 2nd Hello Barcelona Programming Bootcamp in collaboration with Moscow Workshops ACM ICPC starting September 27.

All the top Russian teams are coming, including St. Petersburg State University, MIPT, Ural Federal University, Tomsk, Novosibirsk, Saratov and Perm, as well as the world’s top universities such as Waterloo, Central Florida, Hangzhou Dianzi, Singapore, KTH and dozens of others — so far teams from 30 countries have signed up.

The event’s gold sponsor is Sberbank, the biggest commercial and investment bank of Eastern Europe and Russia. Thanks to their support we expect that the top participants will be awarded valuable prizes, alongside high-profile internship and job opportunities.

We can’t wait to see all of you coming to learn, practice and compete on the international stage, smoothing your road towards April World Finals in Beijing.

Ps. Registrations close on September 1.

UPD: Editorial is published

Congratulations to the winners:

Congratulations to the best hackers:

1326 successful hacks and 300 unsuccessful hacks were made in total!

And finally people who were the first to solve each problem: