By enot110, history, 5 weeks ago, translation, In English


This round is sponsored by esports team cybercats. The team was founded in October 2021 by me and subscriber.

We currently have a Dota 2 roster, playing in the second division of EEU DPC. Come support us on streams and in the comments!

As a thank you to Codeforces and the competitive programming community, we decided to make this round and give away 100 plush cybercats!

The prizes will be awarded to the first 100 places in the round.

Follow our social networks:

   (RU) VK    (RU) telegram    (RU) youtube    (EN) twitter.

The problem set was prepared by subscriber, isaf27, KAN, Catmoonlight, jdurie and BucketPotato.

Round was tested by enot110, izban, qwerty787788, MateoCV, ilyakrasnovv, tlsdydaud1, ak2006, Valters07, DiegoGarcia, Chaska, kzyKT, Div1D4Life, FedeNQ, alysonNBS, petertromso and jojonicho.

UPD. Scoring distribution: 500 — 1000 — 1500 — (1500 — 750) — 2250 — 2500 — 3000 — 3500.

UPD. editorial

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By Serval, history, 5 weeks ago, In English

UPD: The start time has been changed. Note that the start time is unusual.

Hi Codeforces!

Bazoka13, Toxel, and I Serval are glad to invite everyone to participate in Codeforces Round 853 (Div. 2), which will be held on Feb/25/2023 17:20 (Moscow time).

This round will be rated for participants with rating lower than 2100. We will be glad to see the participants with a higher rating to take part in our round unofficially as well!

You will be given 6 problems to solve in 2 hours. Scoring distribution will be announced later.

We would like to thank everyone that makes this round possible:

Good luck & Have fun! :P

UPD2: Scoring distribution: 500 — 1000 — 1250 — 1750 — 2000 — 2750.

UPD3: Editorial is out. Thanks for your participation!

Congratulations to the winners!


  1. Allvik06
  2. BurnedChicken
  3. maspy
  4. tute7627
  5. Um_nik

Div. 2:

  1. MakaPakka
  2. inhabitant
  3. b8LI
  4. Reisael
  5. stkwill

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By dario2994, history, 6 weeks ago, In English

The Southwestern Europe Regional Contest will take place on the 19th of February in Milan. It is the ICPC regional contest (i.e., the winning teams will advance to the ICPC World Finals) for teams from France, Israel, Italy, Portugal, Spain, and Switzerland.

The mirror contest SWERC 2022-2023 - Online Mirror (Unrated, ICPC Rules, Teams Preferred) will be held on Codeforces at Feb/19/2023 14:05 (Moscow time) and will last 5 hours.

The mirror contest will contain the problems from the official competition plus some additional problems.

I am the chief judge for the competition and I want to thank:

I invite you to participate in the contest and I hope that you will like the problems.

On the difficulty
The contest features problems with difficulties from div2A to div1F; so anyone can find something at their level.

Many teams with little experience participate in SWERC, so the problem set should be enjoyable also for div2 contestants. On the other hand, solving all the problems should be challenging even for the strongest teams in the world: the MIT team did not AK in 5 hours.


  1. The contest is unrated, so your codeforces rating will not be affected.
  2. The scoring is ICPC-style: teams are first sorted by number of problems solved, then the time-penalty is used as a tie-break. An incorrect submission gives a 20 minutes penalty.
  3. We encourage participation as a team.
  4. If you are participating in a team, we encourage you to use only one computer for coding the solutions (as in an ICPC contest). Regarding using templates, googling, and copy-pasting code: feel free to do it.
Rationale of rule 4.

UPDATE: We hope you liked the problems!

We uploaded the editorial of the contest (you can find it at, among the contest materials).

The solution to problem N submitted in the mirror contest by the team Let it rot is a quadratic solution which they managed to squeeze in the time limit. This was not the expected solution. So, morally, this problem is still unsolved! In the next days I might decrease the time limit. We have a solution which gets AC in less than one second but we wanted to be generous with the time limit. It turns out, we were too generous.

Congratulations to all the participants of the onsite contest and in particular to the three teams solving 11 problems:

  1. ENS Ulm 1 -- École Normale Supérieure de Paris
  2. gETHyped -- ETH Zürich
  3. P+P+P -- Harbour.Space University

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By awoo, history, 6 weeks ago, translation, In English

Hello Codeforces!

On Feb/16/2023 17:35 (Moscow time) Educational Codeforces Round 143 (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 extended 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 6 or 7 problems and 2 hours to solve them.

The problems were invented and prepared by Adilbek adedalic Dalabaev, Vladimir vovuh Petrov, Ivan BledDest Androsov, Maksim Neon Mescheryakov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Good luck to all the participants!

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

Hello Codeforces!

We look forward to seeing Mike Mirzayanov and Nikolay Kalinin again at our Barcelona campus when they teach Advanced Algorithms and Data Structures.

In this course, students focus on key and in-depth algorithms and data structures that form a modern computer specialist’s toolkit.

We are always excited to see Codeforces participants as our students at Harbour.Space! Once again we are giving a special discount for the single course participation in Barcelona, Spain (travel costs and accommodation are not included).

Sign Up Here→

50% of the spots have been filled already, hurry up not to miss your opportunity to get selected!

At Harbour.Space University, we continue providing work-study opportunities; in this case, we offer motivated Data Scientists the opportunity to work and study in Barcelona in partnership with Noventiq, the leading global solutions and services provider in digital transformation and cybersecurity.

We are looking to distribute scholarships for intensive study programmes at the highest level for eligible candidates that will join our journey.

Candidates will be working on the following tasks:

  • Invent and implement approaches to solving problems of computer vision and machine learning, form requirements together with the team;
  • Plan experiments, train models, evaluate their quality and embed them in pipelines;
  • Work with data, the formation of technical requirements for markup;
  • Register the results of training runs of models and track the dynamics of their performance;
  • Write algorithms for pre and post-processing of images and videos, the logic of scenarios for processing media data;
  • Conduct research in the field of Computer Vision: classification, detection, segmentation;
  • Engage in the optimization of neural networks: distillation, quantization, pruning;
  • Prepare models for production.
  • Carry out the development of custom algorithms and modules for our video analytics platform

All successful applicants will be eligible for a 100% Tuition Fee Scholarship (22.900 €/year) provided by Noventiq company for the Data Science programme.


Study Commitment: 3 hours/day You will complete 15 modules (each three weeks long) in one year. The daily class workload is 3 hours, plus homework to complete in your own time.

Work Commitment: 6 hours/day Immerse yourself in the professional world during your apprenticeship. You’ll learn from the best and get to apply your newly acquired knowledge in the field from day one.

University requirements

  • Bachelor's degree in the field of Mathematics, Statistics, Data Science, Computer Science or similar
  • English proficiency

Work requirements

  • Excellent knowledge and experience in using Python, as well as TensorFlow/PyTorch;
  • Experience in implementing Deep Learning models for commercial projects;
  • Experience in solving real problems in the field of Computer Vision
  • Experience with Linux OS, Git, Docker;
  • Understand the principles of operation of current popular architectures of neural networks;
  • Possession of the culture of conducting experiments, you know about reproducibility and logging, you can objectively assess the quality of the model;
  • Spanish language proficiency;
Apply Here Now→

UPD: Editorial is out

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By antontrygubO_o, 6 weeks ago, In English

Hello everyone! The 4th Stage of the 1st Universal Cup: Ukraine, will be held on Feb 18th, 2023.

The contest is based on 1/8 and 1/4 Ukrainian stages of SEERC 2023, plus some extra problems. Please, don't participate, if you have seen these problems. This contest also serves as Day 1 in Osijek Competitive Programming Camp 2023 on February 18, 2023.

Author of all problems: antontrygubO_o. I hope you like the problems.

You can participate in the contest in the following three time windows:

  • Feb 18th 13:00 — 18:00 (UTC +8)
  • Feb 18th 19:00 — 24:00 (UTC +8)
  • Feb 19th 02:00 — 07:00 (UTC +8)

Please note that you can see two scoreboards in DOMjudge. The 'Local Scoreboard' shows the standings ONLY IN THE CURRENT TIME WINDOW. And the 'Combined Scoreboard' shows all participants, including the onsite participants, and the cup participants in the previous time windows.

Contest link:

Universal Cup Scoreboard:

About Universal Cup:

Universal Cup is a non-profit organization dedicated to providing trainings for competitive programming teams. Up to now, there are more than 200 teams from all over the world registering for Universal Cup.

A more detailed introduction:

Register a new team:

UPD1: Thanks for your participation! Here is Editorial.

I also uploaded contest to gym: Anton Trygub Contest 1 (The 1st Universal Cup, Stage 4: Ukraine).

I hope to add ghost participants by tomorrow.

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By MikeMirzayanov, 7 weeks ago, In English


Of course, there was an unpleasant incident with the problem today. In fact, the problem almost coincided with another problem in the old round, which was hosted 5 years ago.

You, of course, are shocked. You, of course, think that the round should be unrated.

You are wrong. Here's why.

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By vaaven, history, 7 weeks ago, translation, In English

Hi everybody,

This Sunday there will be a Moscow Olympiad for Young Students. 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, 541, 545, 567, 583, 594, 622, 626, 657, 680, 704, 707, 727, 751, 775, 802, 829).

The round will be held at Feb/12/2023 11:35 (Moscow time) and will last for 2 hours. Note the unusual time of the round. The round will be held according to the Codeforces rules and will be rated.

Problems of this competition were prepared by Tikhon228, TheEvilBird, Ormlis, vaaven, Gornak40, Honey_Badger guided by vaaven, grphil and Helen Andreeva.

Thanks to Artyom123 for the round coordination, and also thanks for MikeMirzayanov for systems Codeforces and Polygon, which was used to prepare problems of this olympiad.

Thanks to BucketPotato, KseniaShk, NemanjaSo2005, MagentaCobra, kuertov, prvocislo, 4qqqq, vsinitsynav, FynjyBath, qualdoom, ivanlarin, didedoshka, petyb, PBBx0, MIKHANGO, charlyk, RP-1, talant, ak2006 for testing.

Due to the official competition source codes of other participants will not be available for an hour after the end of the round.

Good luck everybody!

UPD: Score distribution: 500 — 1000 — 1250 — 1750 — 2500 — 3250

UPD2: Еditorial

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By azberjibiou, history, 7 weeks ago, In English

Hello Codeforces and welcome back to another div2 round.

YeongTree and I are excited to invite everyone to participate in Codeforces Round 851 (Div. 2), which will be held on Feb/09/2023 17:35 (Moscow time).

This round is rated for the participants with ratings strictly lower than 2100. You will be given 6 problems and 2 hours to solve them. All the problems are authored and prepared by YeongTree and me.

We would like to thank

The score distributions will be updated later.

UPD1: Score distribution: $$$500−1000-1500-2250−2500-3000$$$

UPD2: Congratulations to the winners!


  1. jiangly
  2. MakaPakka
  3. Puranya_
  4. maspy
  5. tute7627

Rated participants

  1. MakaPakka
  2. _10circle_
  3. JJcjn
  4. 1cm
  5. YouPervertSucker

AC submissions at the last second

UPD3: Editorial is out

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By tourist, 2 months ago, translation, In English


Welcome to Codeforces Round 850 (Div. 1, based on VK Cup 2022 - Final Round) and Codeforces Round 850 (Div. 2, based on VK Cup 2022 - Final Round) that will start on Feb/05/2023 15:05 (Moscow time). Both rounds will be rated.

This round is a mirror of VK Cup 2022 Final — annual programming championship for Russian-speaking competitors organized by VK. VK Cup started in 2012 and has grown to be a five-track competition in competitive programming, Mobile, ML, Go, and JavaScript.

All the problems of Div. 1 round are authored and prepared by me, while KAN authored and prepared two problems for Div. 2. Thanks to errorgorn, irkstepanov, qwerty787788, Merkurev, IgorI, PavelKunyavskiy, izban, Alexdat2000, I_Remember_Olya_ashmelev, Akulyat, mike_live, Ekler, Kalashnikov for making this round better.

You will be given 6 problems and 3 hours to solve them.

UPD: Editorial

Congratulations to the winners:

  1. ksun48
  2. maroonrk
  3. afo
  4. Mr_Eight
  5. ecnerwala

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