Hey Codeforces!

We’re thrilled to invite you guys to Codeforces Round #542, which is going to take place on Sunday, February 24, 2019, at 18:35 MSK. There will be a separate round for each division, and they will be rated!

Problems were prepared by zoomswk and me. As the round authors, we would like to thank ksun48, isaf27, tuna_salad, and Um_nik for testing the problems; 300iq and KAN for their help and advice in contest preparation; and the invisible MikeMirzayanov for the incredible Codeforces and Polygon platforms.

Each division will be given 6 tasks and 2 hours to solve them. As per the Codeforces tradition, scoring distributions will be revealed shortly before the round.

We wish you the greenest verdicts and hope that you’ll enjoy the tasks.

This round is in honor of Alex Lopashev who has supported Codeforces on its anniversary. Some words from MikeMirzayanov:

Alex Lopashev studied at Programming Competitions Training Center (in Saratov U) headed by me. I was really happy (and even proud!) to see his contribution on the 8th anniversary of Codeforces. I am sure that a large number of young people got a lot from our community, even if they did not achieve high results in competitions. It's great that there are those who remember and appreciate it. Thank you, Alex!

Good luck!

UPD1: Shortly after the contest, we'll be on the community Discord server to discuss the tasks.

Hi everybody,

This Sunday there will be a Moscow programming competition for school students of grades from 6 to 9. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Open Olympiad, Moscow Team Olympiad and Metropolises Olympiad (rounds 327, 342, 345, 376, 401, 433, 441, 466, 469, 507, 516).

Round will be held at 10:05 UTC on Saturday. You will be given 6 problems and 2 hours to solve them. Round will be rated for second division (rating below 2100). As usual, participants from the first division can participate in a contest out of competition.

Problems are prepared by V--gLaSsH0ldEr593--V, grphil, _kun_, VFeafanov, Sehnsucht, Sender, voidmax under my supervision.

Thanks to _kun_ for the round coordination and statement translation, and also thanks for MikeMirzayanov for systems Codeforces and Polygon, which was used to prepare problems of this olympiad.

Good luck everybody!

UPD1: Due to some last-minute changes, there will be 7 problems.

UPD2: Winners!

Div 2:

1. Big_Red_Dates

2. PinkieRabbit

3. disposrestfuIIy

4. Dobrobober

5. szh0808

6. prodakcin

7. Argentina

8. afedor

9. bigelephant29

10. Young25

Div.1 + Div.2:

1. JustasK

2. BigBag

3. egor.lifar

4. Big_Red_Dates

5. waynetuinfor

6. dreamoon_love_AA

7. danya090699

8. KrK

9. Farhod_Farmon

10. PinkieRabbit

UPD3: Editorial

Microsoft’s Quantum team is excited to announce the Q# Coding Contest – Winter 2019! In this contest you can put your quantum programming skills to the test, solving quantum computing tasks in Q#. Winners will receive a Microsoft Quantum T-shirt!

Quantum computing is a radically different computing paradigm compared to classical computing. Indeed, it is so different that some tasks that are believed to be classically intractable (such as factoring integers or simulating physical systems) can be performed efficiently on a quantum computer. In 2017 Microsoft introduced the Quantum Development Kit which includes the Q# programming language. Q# can be used with Visual Studio, Visual Studio Code or the command line, on Windows, macOS, and Linux.

In summer of 2018 we hosted the first quantum programming contest, which included problems on introductory topics in quantum computing: superposition, measurement, quantum oracles and simple algorithms. This contest will offer harder problems on some of these topics as well as introduce some new topics.

The contest will run from March 1 to March 4.

Miss Div. 3 rounds? :)

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Hello!

Codeforces Round #540 (Div. 3) will start at Feb/19/2019 17:35 (Moscow time). You will be offered 6 or 7 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. However, all of you who wish to take part and have rating 1600 or higher, can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 or 7 (or 8) problems and 2 hours to solve them.

Note that the penalty for the wrong submission in this round (and the following Div. 3 rounds) is 10 minutes.

Remember that only the trusted participants of the third division will be included in the official standings table. As it is written by link, this is a compulsory measure for combating unsporting behavior. To qualify as a trusted participants of the third division, you must:

• take part in at least two rated rounds (and solve at least one problem in each of them),
• do not have a point of 1900 or higher in the rating.

Regardless of whether you are a trusted participant of the third division or not, if your rating is less than 1600, then the round will be rated for you.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of my work. Thanks to my good friends Mikhail PikMike Piklyaev, Maksim Ne0n25 Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

I also would like to say that participants who will submit wrong solutions on purpose and hack them afterwards (example) will not be shown in the hacking leaders table.

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UPD: Due to the problems being really interesting the round will last 2 hours 15 minutes.

UPD2:

Congratulations to the winners:

Congratulations to the best hackers:

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

UPD3: Editorial is published!

Hello Codeforces!

On Feb/18/2019 18:40 (Moscow time) Educational Codeforces Round 60 (Rated for Div. 2) 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.

This round will be rated for the participants with rating lower than 2100. It will be held on extented ICPC rules. The penalty for each incorrect submission until the submission with a full solution is 10 minutes. After the end of the contest you will have 12 hours 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 invented and prepared by Roman Roms Glazov, Adilbek adedalic Dalabaev, Vladimir Vovuh Petrov, Ivan BledDest Androsov, Abizer Reziba Lokhandwala and me.

Good luck to all participants!

Our friends at Harbour.Space also have a message for you:

Attention tech specialists!

Harbour.Space Barcelona is proud to announce a collaboration with one of our industrial partners to offer a fully funded scholarship for our one year Master’s in Data Science Programme at HSU Barcelona.

The Scholarship includes:

• Full coverage of the Programme’s tuition fee (€23,000 value)
• 3 hours of study a day at Harbour.Space University
• 4 hours of internship a day with one of our industrial partners
• €12,000 euros a year (living allowance)

Our data science programme will feature super star teachers like Mike Mirzayanov (Advanced Algorithms and Data Structures), Alexey Dral (Big Data: Map Reduce, Spark, BigTable/HBase) and Alex Dainiak (Discrete Optimisation), plus many more.

Harbour.Space is unique because:

1. We don’t play by the rules. We bring practicing professionals, not only academic teachers, who come teach for intense, 3 week modules. HSU students are encouraged to experiment, fail, and try again, until they succeed.

2. We are your home. Harbour.Space is a community of over 40 nationalities, and we're still growing.

3. We provide an experience. Harbour.Space University is located in Barcelona, one of the most vibrant cities of our time.

If you are interested in the scholarship, fill out the form below and we will contact you about the next steps.

Congratulations to the winners:

Congratulations to the best hackers:

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

UPD: The editorial is out

Good day to you, Codeforces!

Let me introduce you Codeforces Round #539, that will take place at Saturday, February 16, 2019 at 19:35. The round will be rated for both divisions.

The problems of this round were developed by markysha, xolm, aleex. That is our first round on Codeforces, and I hope not the last one :)

Thanks everyone who helped with tasks preparation:

• Our coordinator arsijo for his help with everything
• Thanks very much kefaa2, GandalfTheGrey, sharepoLOVEDDD, austrian_artist, Adalbert, StasyaCat, Fekete and Daryusz for testing this round (yeah, we approached testing thoroughly :))
• gepardo for playing a crutial role in the contest (what? you'll see)
• And of course MikeMirzayanov for Polygon and Codeforces.

There will be 6 tasks and 2 hours 30 minutes to solve them. As usual, the score distribution will be revealed shortly before the contest.

Wish you quick ideas and short solutions!

Upd.
Div. 1: 500 — 1250 — 1750 — 1750 — 2250 — 3000
Div. 2: 500 — 1000 — 1500 — 2250 — 2750 — 2750

Editorial

Final results are ready!

Div 1:
1. Um_nik
2. wxhtxdy (was so close...)
3. knightL
4. Swistakk
5. ToTLeS

Div 2:
1. schtomi97
2. Dev0302
3. revivedDevil
4. miseri
5. fragusbot

Congratulations to the winners!

Maybe see you later...

TREMBLE BEFORE THE MIGHTY OMEGALULGRAPE

Hello Codeforces!

We are honored to invite you to Codeforces Round #538 (Div. 2), which will take place at Feb/10/2019 17:05 (Moscow time). The round will be rated for all Division 2 participants (with rating less than 2100). Still, we warmly welcome Division 1 participants to join us out of competition.

You will be given 6 problems to solve in 2 hours. The round's problems were initially prepared by Duy-Bach Akikaze Le, Xuan-Tung neko_nyaa Nguyen and Xuan-Quang xuanquang1999 D. Nguyen.

There will be an interactive problem in this round. Learn more about interactive problems here.

This is our first attempt in making a Codeforces round, so suggestions are much welcome to help us improve ourselves. ;)

We also want to thanks many friends for making this round possible:

• Dmitry _kun_ Sayutin for coordinating the round, providing a neat idea on one problem and some Russian translations.
• Andrew GreenGrape Rayskiy for various suggestions on the problems, some other Russian translations, and most importantly, peacefully submitted himself to be quarantined from pretests. ;)
• Michal majk Svagerka for testing the round.
• And last but not least, Mike MikeMirzayanov Mirzayanov for the amazing Codeforces and Polygon platform, without which this round would never be possible :D

P/s: I will be at the Discord CP Community to discuss the problems after the coding phase. However, please follow the rules and don't discuss the problems during the contest by any means.

Wish everyone good luck and high rating!

UPD1: Score distribution: 500-1250-1500-2000-2000-2750

UPD2: Editorial is published.

UPD3: The contest is finished. I apologized for the "somewhat" weak pretests at here and there. Anyway, time to celebrate our winners ;)

Official participants:

1. xlk200
2. vasilescu_mihai
3. Cinro_9baka
4. africamonkey
5. 2019_BecameMaster
6. cdsfcesf
7. yww_AFO
8. hr_tian_xia_di_2
9. JZmster
10. chinmay0906

Div.1 + Div.2 participants:

1. Hazyknight
2. tfg
3. tempura0224
4. xlk200
5. sava-cska
6. mango_lassi
7. I_love_Tanya_Romanova
8. ec24
9. vasilescu_mihai
10. Cinro_9baka

Hi!

Tomorrow, at Feb/07/2019 16:35 (Moscow time) we will host Codeforces Global Round 1.

It is the first round of a new series of Codeforces Global Rounds. The rounds are open for everybody, the rating will be updated for everybody.

The prizes for this round:

• 30 best participants get a t-shirt.
• 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.

The prizes for the 6-round series in 2019:

• In each round top-100 participants get points according to the table.
• The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
• The best 20 participants over all series get sweatshirts and place certificates.

The problems of this round were developed by a team of authors: aitch, simonlindholm, grphil, V--gLaSsH0ldEr593--V, GreenGrape, Nebuchadnezzar, _kun_ and me. Thanks arsijo and _kun_ for their help in the round's coordination, and also majk, pashka, Jeel_Vaishnav, Ashishgup and UnstoppableSolveMachine for testing the round!

Good luck!

Congratulations to the winners!

1. tourist
2. Um_nik
3. TLE
4. mnbvmar
5. sunset
6. wxhtxdy
7. ksun48
8. cki86201
9. snuke
10. fateice

Editorial.