By Vladosiya, history, 35 hours ago, translation, In English

Hello! Codeforces Round 946 (Div. 3) will start at May/20/2024 17:35 (Moscow time). You will be offered 6-8 problems with expected difficulties to compose an interesting competition for participants with ratings up to 1600. However, all of you who wish to take part and have a rating of 1600 or higher, can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, it will be a 12-hour phase of open hacks.

You will be given 7 problems and 2 hours and 15 minutes to solve them.

Note that the penalty for the wrong submission in this round 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 participant of the third division, you must:

  • take part in at least five 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.

Round is based on UKIEPC 2024: Spring Practice. Please refrain from participating in this round if you are familiar with the tasks of this competition.

I would like to thank:

  1. Authors of the original comtpetition: Aksenov239, MaxBuzz, RobinFromTheHood, darnley, izban, pkhaustov, lsantire, az453, fedor.tsarev, Shoaib Jameel.

  2. MikeMirzayanov for help with ideas and Polygon and Codeforces platforms.

  3. -is-this-fft-, peltorator, tute7627 for red testing.

  4. senjougaharin, kaikey, gmusya, nskybytskyi, Giga_Cronos, diskoteka for yellow testing.

  5. TypeYippie, kzyKT, tepamid, ahshafi for purple testing.

  6. Abo_Samrah, Zandler, sam07a, YESMAKHAN, xygzy, Klaus26 for blue testing.

  7. Morvolzz, dasha..zhilina, sutekine, Muhsen, Gojova, Acanikolic73 for cyan testing.

  8. You for participation.

Good luck!

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By prvocislo, 6 days ago, In English

Ahoj, Codeforces!

We are excited to invite you to participate in Codeforces Round 945 (Div. 2), which will start on May/17/2024 17:35 (Moscow time).

The problems are authored by TimDee and prvocislo.

This round will be rated for participants whose rating is below $$$2100$$$. Participants with higher ratings are encouraged to participate out of the competition.

You will be given $$$6$$$ problems and $$$2$$$ hours to solve them. The scoring distribution is bellow. One of the problems will be interactive. Please read this blog to get familiar with this type of problems.

We would like to thank everyone, who made this round happen:

Scoring distribution: $$$500-1000-1500-2000-2250-3000$$$

Good luck, have fun and see you on Friday! ✩₊˚

Upd: Congratulations to the Winners!

Div 2:

1) _MyGO_Tomori_

2) Sxy_Limit

3) LofiGirl

4) prins

5) SXWZ-Queenie

Div 1+2:

1) BucketPotato with first AK!

2) gamegame

3) hitonanode

4) abc864197532

5) peti1234

Upd2: Editorial is out!

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By adamant, history, 5 days ago, In English

Hi everyone!

We organized an onsite competitive programming contest at ETH Zürich on May 11th, 2024. The contest is now uploaded to the Codeforces gym at ETH Zurich Competitive Programming Contest Spring 2024.

The onsite contest was 5h long and we recommend for you to participate in teams. In the onsite contest only one computer was allowed but participants could access the internet freely. The difficulty of the problemset is slightly easier than a regional ICPC contest but also offers a few hard problems. Difficulty range is from div2 A to div2 G.

Thanks a lot to all problem setters: BenniKartefla, Lakii, Lebossle, MihneaDAVID, OhLee, TecTrixer, ackj, adamant, alagorithmet and mango_lassi.

Additionally, a big thanks to all our testers and reviewers: Petr, Evirir, CSQ31, atakanysr, FatihSolak, qwexd, AhmetKaan, Macdu, atli164, SATSKY_2024target_IGM, SuprDewd, Tagl, Tobo, wildfire032, fried-chicken, theodor.moroianu and sischu74.

Tutorial Slides can be found here.

Congratulations to the top 5 of the onsite contest:

  1. mETHroners: GRT_2018, Meloric, paula
  2. Mr Malnars Lethal Peppers: pavkal5, DBradac, dpaleka
  3. uhh this should actually be first place, sorry, system error: AimShootReload, donentseto
  4. ML and AC: miguell, Andrei1998
  5. CrispyBeef: tiagodias, jonathanplsmith, Blackphoenyx

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By BledDest, history, 2 weeks ago, In English

Greetings Codeforces!

First things first, we would like to thank everyone who participated in the previous nine Kotlin Heroes competitions: Episode 1, Episode 2, Episode 3, Episode 4, Episode 5: ICPC Round, Episode 6, Episode 7, Episode 8 and Episode 9.

Kotlin Heroes is a great way to play around with Kotlin’s features, learn something new, and practice using the language by solving fun problems. It is great for programmers of any level!

We invite you to join the practice round, where you can improve your algorithmic problem-solving skills and complete training problems. In this round, all the solutions are open and you can request hints if you’re stuck.

Here are some things you can do to help you refresh your knowledge of Kotlin and learn more about competitive programming while you practice:

On May 13, 2024, the real challenge begins! Kotlin Heroes: Episode 10 will last 2 hours 30 minutes and will feature a set of problems ranging from simple ones, which are designed to be solvable by anyone, to some really tricky ones for seasoned competitive programmers.


You can solve Codeforces challenges directly from your JetBrains IDE using its smart features. Just enable the JetBrains Academy plugin and follow the instructions in the Getting started with Codeforces guide.


The top three winners will receive cash prizes of $512, $256, and $128 (or rewards of equivalent value), respectively. The top 50 participants will win a Kotlin Heroes T-shirt and an exclusive Kotlin sticker, and all competitors who solve at least one problem will be entered into a raffle for one of 50 Kotlin Heroes T-shirts.

Please note that we are not able to ship prizes to any country, state, province, or territory subject to comprehensive OFAC sanctions, including Belarus, Cuba, Iran, North Korea, Russia, Syria, or the Crimea, Donetsk, or Luhansk regions. To see the list of sanctioned countries and regions, please visit this page.

Best of luck to everyone!

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Announcement of Kotlin Heroes: Episode 10
Announcement of Kotlin Heroes: Practice 10
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By flamestorm, 11 days ago, In English

Hi, Codeforces!

mesanu, SlavicG and I are very excited to invite you to Codeforces Round 944 (Div. 4)! It starts on May/10/2024 17:35 (Moscow time).


The format of the event will be identical to Div. 3 rounds:

  • 5-8 tasks;
  • ICPC rules with a penalty of 10 minutes for an incorrect submission;
  • 12-hour phase of open hacks after the end of the round (hacks do not give additional points)
  • after the end of the open hacking phase, all solutions will be tested on the updated set of tests, and the ratings recalculated
  • by default, only "trusted" participants are shown in the results table (but the rating will be recalculated for all with initial ratings less than 1400 or you are an unrated participant/newcomer).

We urge participants whose rating is 1400+ not to register new accounts for the purpose of narcissism but to take part unofficially. Please do not spoil the contest for the official participants.

Only trusted participants of the fourth division will be included in the official standings table. This is a forced measure for combating unsporting behavior. To qualify as a trusted participant of the fourth division, you must:

  • take part in at least five rated rounds (and solve at least one problem in each of them),
  • do not have a point of 1400 or higher in the rating.

Regardless of whether you are a trusted participant of the fourth division or not, if your rating is less than 1400 (or you are a newcomer/unrated), then the round will be rated for you.


Thanks a lot to the testers: Dominater069, nskybytskyi, ScarletS, Gheal, BucketPotato, JustJie, htetgm, Vladosiya!

We suggest reading all of the problems and hope you will find them interesting. Good luck!

UPD: Editorial is out!

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By ICPCNews, 7 weeks ago, In English


Hello, Codeforces!

The ICPC Challenge World Finals in Luxor is approaching for some of you, and we are delighted to provide an additional exciting opportunity to compete open to all!

We are happy to invite you to the 2023 Post World Finals Online ICPC Challenge, powered by Huawei starting on May 6, 2024 at 15:00 UTC and ending on May 20, 2024 at 14:59 UTC.

In this Challenge, you will have a unique chance:

  • to compete with top programmers globally

  • to solve 1 exciting problem prepared by Huawei

  • to win amazing prizes from Huawei!

It is an individual competition.

2023 Post World Finals Online ICPC Challenge powered by Huawei:

Start: May 6, 2024 15:00 UTC

Finish: May 20, 2024 14:59 UTC

We hope you'll enjoy this complex Challenge!


We are glad to propose to you an exciting challenge “Accuracy-preserving summation algorithm”, which is prepared by Huawei Computing Product Line.

With this challenge, we focus on summation algorithms of floating point numbers in different precisions with the goal to use the lowest possible precision without losing too much of the accuracy of the end result. This problem arises in high-performance computing as lower precision can be computed faster. At the same time it also loses accuracy faster and can even lose it completely. Finding the right balance between fast low precision calculations and higher precision intermediate summations is a challenging task on modern architectures, and you would have an opportunity to try addressing this challenge


Prizes from Huawei

Rank Prize
Grand Prize (Rank 1) € 12 000 EUR + a travel trip to the 48th Annual ICPC World Finals in a guest role
First Prize (Rank 2-10) € 8,000 EUR
Second Prize (Rank 11-30) € 3,000 EUR
Third Prize (Rank 31-60): € 800 EUR
TOP 200 Participants Souvenir T-shirt
* If the allocated Huawei Challenge prize cannot be delivered to your region for any reason it may be replaced by another prize (if no legal restrictions), at the discretion of the Sponsor.

Challenge Rules and Conditions

By participating in this Challenge, you agree to the Challenge Rules and Conditions of Participation

Good luck, we hope this will be fun!

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By Cauchico, history, 3 weeks ago, In English

Hello Codeforces!

Back from the dead, we'd like to invite you to the online mirror of the Helvetic Coding Contest, Switzerland open championship! You can find past mirror from 2019, 2018, 2017, and 2016.

The Helvetic Coding Contest used to be held yearly at EPFL. This year, the Polympiads association is bringing it back alive! The contest itself took place on April the 13th, but the online mirror is scheduled on Saturday, 4th of May, 09:05 Swiss time. The duration is 4:30.


  • you can participate in teams or individually with a single computer (1-3 people),

  • standard ACM-ICPC rules (no hacking),

  • the contest is not rated,

  • if you have participated in the onsite contest, please do not participate in the mirror.

Contrary to what the mirror's date might lead you to believe, this year's theme is Harry Potter. It features 7 series of 3 related tasks with increasing difficulty (easy/medium/hard). Note that we do not guarantee that all problems are solvable using python.

Thanks a lot to:

UPDATE: Editorial is out, also available as a PDF. Thanks all for participating!

UPDATE 2: Congratulations to the winners who solved all 21 subtasks:

  1. thinking: Ormlis, Mangooste
  2. Captain take me!: crazy_sea, A_zjzj, 275307894a
  3. japan406364961: Nyaan, kotatsugame, risujiroh
  4. Qingyu Fan Club: xinyoudui, GapGapGap, InfiniteStarlight
  5. Idea Generators Club: tedi_2.0, Denisov, Valera_Grinenko
  6. 244mhq
  7. jiangly

UPDATE 3: Also huge congratulations to the winners of the onsite round (no prewritten code or Internet access was allowed, so the conditions were a bit different):

  1. Felt smart (might un-participate later) — 20 subtasks
  2. Nameless Silly Moon — 18 subtasks
  3. ***IsEvil? — 17 subtasks
  4. Breakfast Master Toaster — 16 subtasks
  5. Hairy Stofler — 16 subtasks
  6. thethingswedoforpizza — 15 subtasks
  7. huchibuchi — 15 subtasks

We hope you enjoyed the problems, please share your thoughts in comments!

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