By MikeMirzayanov, history, 2 months ago, In English

Hello, Codeforces.

It's scary to think about it: there are already almost 1800 rounds in the list of past contests!

I started adding a filter to the table with these rounds. Right now, you can already filter by some of the types of rounds. Here's what I've supported:

  • Div. 1
  • Div. 2
  • Div. 3
  • Div. 4
  • Div. 1 + Div. 2
  • Educational Rounds
  • CodeTON Rounds
  • Globals
  • Kotlin Rounds
  • VK Cup Rounds
  • Long Rounds
  • April Fools

Of course, I might have forgotten some types of contests. Please remind me if I missed anything. We should pay attention only to types where we have conducted several contests of that type.

I plan to expand this filter by adding more settings. Perhaps it would be good to filter by the condition "has at least one submission in this contest" (or those for which no submissions at all). What do you think?

What else would you suggest adding?

P.S. Here is how it looks on the website (some intermediate version, some options may be missing).

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By BledDest, 2 months ago, In English

I don't think comments like "you use X in model solution, author, are you an idiot?", "f**k you and your problems, they are shit" and such should be normal on Codeforces, especially when written by someone high-rated and/or respected in the community. I also don't think this kind of behavior should be normal towards regular users.

I know that sometimes contests can be frustrating. Sometimes it is the participant's fault, sometimes it is the problemsetter's fault, sometimes it just happens without anyone being guilty of that. And I understand that in some cases, the criticism the author receives is fair and well-deserved.

But there is a fine line between criticism, saying that you didn't like the problems, and hurling insults against the author. The former two are acceptable (and sometimes even needed, because authors have to improve and learn from their mistakes); the latter one, in my opinion, should not be acceptable.

It's not like we can ever get rid of offense and hatred completely; there will always be people who want to take it out on the community as a whole or someone specific. And if I created a blog for every time I saw an insult hurled towards me or some other member of the community, my account would already be banned for spamming. But I think that the comments like the one linked in the first paragraph are especially dangerous and need to be dealt with.

Codeforces community is biased towards people with high rating and people who do something for the website. And this is sometimes a good thing; but it can also make people think that if a high-rated participant and a problemsetter allows himself (or herself) to be rude and offensive, then it is acceptable, and they are allowed to do it as well. That's why cases like this one are especially bad.

We can never get rid of offense and hatred, but please don't make it something normal. Everyone should be responsible for what they are saying or writing, but if your word has some weight in the community, then it also means some additional responsibility for you. Please don't make people think that insulting the author (or anyone else, for that matter!) is perfectly reasonable and fine — I doubt you will like the results of that.

UPD: It looks like the focus of the comment section has shifted towards discussing how to give constructive feedback to the problemsetters. This is certainly one of the points of the blog, but the main thing I wanted to state was that insults against anyone should not be acceptable. It's just that the problemsetters usually get the most of the hatred on CF, so it's much easier to find the examples of that. But this behavior towards regular users should not be allowed either.

UPD2: Initially, there was a link to the comment which caused me to write this whole blog (a comment by a high-rated user and a problemsetter when he openly called another problemsetter retarded because of some details of the solution). I wanted to show it as a clear example, but it was not the right thing to do.

To the person whose comment I used as an example (if you're reading this): I apologize, I shouldn't have made it seem like you're the culprit, and I didn't understand the consequences of my blog fully. I know that you have openly admitted your mistake, and I admire you for that. If the fact that I've used you as an example made you feel awful, or made some other people call you out — I am terribly sorry.

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By TheScrasse, history, 2 months ago, In English

Ciao, Codeforces! We're glad to invite you to take part in Codeforces Round 889 (Div. 1) and Codeforces Round 889 (Div. 2), which will start on Jul/29/2023 17:35 (Moscow time). You will be given 6 problems and 2 hours and 30 minutes to solve them in both divisions.

  • One of the problems will be divided into two subtasks.
  • One of the problems will be interactive, so please read the guide for interactive problems if you are not familiar with it.

The problems were authored and prepared by akifpatel, dario2994, Kaey and me.

We would like to thank

Score distribution:

  • Div. 1: $$$(750 + 750) - 1500 - 1500 - 2000 - 2750 - 3250$$$
  • Div. 2: $$$500 - 1000 - (1250 + 1250) - 2500 - 2500 - 3000$$$

We hope you'll like the problemset!

Update 1: the editorial is out.

Update 2: congratulations to the winners!

Winners and first solves

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By BledDest, history, 2 months ago, translation, In English

Hello Codeforces!

On Jul/27/2023 17:35 (Moscow time) Educational Codeforces Round 152 (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, Mikhail awoo Piklyaev, 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:


Harbour.Space University has partnered with Giga (Unicef) to offer Bachelor's and Master’s degree scholarships in the fields of Data Science, Computer Science and Front-end Development as well as work experience.

We are looking for various junior to mid level candidates:

Data Scientist:

  • Strong ML knowledge
  • Experience with Data Visualization Tools like matplotlib, ggplot, d3.js., Tableau that help to visually encode data
  • Excellent Communication Skills – it is incredibly important to describe findings to a technical and non-technical audience.
  • Strong Software Engineering Background
  • Hands-on experience with data science tools
  • Problem-solving aptitude
  • Analytical mind and great business sense
  • Degree in Computer Science, Engineering or relevant field is preferred

Data Analyst:

  • Cleansing and preparing data
  • Analyzing and exploring data
  • Expertise in statistics
  • Analyzing and visualizing data
  • Reports and dashboards
  • Communication and writing
  • Expertise in the domain
  • Solution-oriented

Front-end Developer:

This student will work closely with the blockchain developer and product lead to contribute to the design and implementation of user interfaces for the company's blockchain-based prototypes. They will be responsible for translating UI/UX design wireframes into functional and visually appealing web applications, ensuring seamless user experiences. The student will collaborate with blockchain and backend developers and designers to integrate front-end components with server-side logic and optimize application performance. They will also be involved in testing, debugging, and maintaining the front-end codebase. The intern will have the opportunity to gain practical experience in front-end development within the context of blockchain technology and contribute to the Giga’s mission of connecting schools to the internet.

  • Solid understanding of HTML, CSS, and JavaScript
  • Familiarity with front-end frameworks and tools such as React or Vue.js.
  • Strong problem-solving skills, attention to detail, and a passion for creating intuitive user interfaces are essential

Full Stack Developer:

  • Interest and experience in web application development, data products and OpenAPIs
  • Comfortable with on-cloud deployment services (preferably Azure), Git and CI/CD pipeline and deployment processes
  • Experience with open-source projects is highly preferred

All successful applicants will be eligible for a 100% tuition fee scholarship (29.900 €/year) provided by the partner company.


Study Commitment: 3 hours/day

You will complete 15 modules (each three weeks long) in one year. Daily class workload is 3 hours, plus homework to complete in your own time.

Work Commitment: 4+ 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.


  • Industry experience
  • International exposure
  • Eager to learn
  • Sustainability is a key topic for you
  • You want to work for an NGO
Apply Now →

UPD: The editorial has been published.

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By Vladosiya, history, 2 months ago, translation, In English

Hello! Codeforces Round 888 (Div. 3) will start at Jul/25/2023 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.

Problems have been created and written by our team: myav, Aris, Gornak40, DmitriyOwlet and Vladosiya.

We would like to thank:

  1. MikeMirzayanov for Polygon and Codeforces platforms.

  2. tute7627 for red testing

  3. oversolver, sevlll777, pavlekn, zwezdinv, Sokol080808, 74TrAkToR, vladmart, EJIC_B_KEDAX, Vladithur, KseniaShk, Be_dos for yellow testing

  4. notyourbae, FBI, meowcneil, NintsiChkhaidze, Phantom_Performer, SashaT9, spike1236, Kalashnikov for purple testing

  5. TheGoodest, Pa_sha, Sasha0738 for blue testing

  6. Syuzi777, Tahseen for cyan testing

Good luck!

UPD: Editorial

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By cry, 4 months ago, In English

Hello Codeforcers!

I am pleased to invite y'all to participate in Codeforces Round 887 (Div. 1) and Codeforces Round 887 (Div. 2), which will start on Jul/23/2023 17:35 (Moscow time). In both divisions, you will be given $$$6$$$ problems and $$$2.5$$$ hours to solve them. The Div. $$$2 $$$ round will be rated for participants with rating below $$$1900$$$, while the Div. $$$1$$$ round will be rated for participants with ratings which are at least $$$1900$$$.

This round was authored and prepared by Benq, emorgan5289, omeganot, US3RN4M3, me (cry), One, synths, buffering, ntarsis30, and ArielShehter.

We want to thank the following people for their contributions:

UPD 1: Score Distribution

Div. $$$2$$$: $$$500 - 1000 - 1500 - 2000 - 2500 - 3500$$$

Div. $$$1$$$: $$$500 - 750 - 1250 - 2000 - 2250 - 3000$$$

UPD 2: Editorial has been posted here

UPD 3: Congratulations to the winners!


  1. jiangly

  2. Rebelz

  3. Radewoosh

  4. tourist

  5. amiya

Div. 2

  1. dmaksym1177

  2. Tmath_OneLove

  3. onufryw

  4. i_nevergive_up

  5. clonegrandmaster

Good luck! Red panda wishes you all rating inflation!

Art credit to xiaossr

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By -is-this-fft-, 2 months ago, In English

Hi everyone!

Sponsored by

After a successful camp last February (announcement, wrap-up), we are happy to announce that Osijek camp will be returning on 16.-24. September 2023 — just in time to prepare for the World Finals in November as well as several regional contests throughout the fall. The camp is hosted by the Department of Mathematics at J. J. Strossmayer University of Osijek and is brought to you by the organizing team of adamant, -is-this-fft- and ajovanov.

The camp is inspired by various competitive programming camps that we attended during our active years in ICPC, and is aimed to help college students prepare for ICPC regional contests and finals. The camp will consist of 7 ICPC-style contests and 2 days off.


Participation fee for onsite participants is 150€ per person. It does not include regular meals, travel or accommodation. Some further details about location, travel and food options can be found on the website.

If you want to participate, but are unable to come onsite, we offer a reduced fee of 100€ per person for online participation. It is also possible to reduce fees individually if you are unable to attend some of the contests. This will be handled on a case-by-case basis.

We support and empathize with those affected by the ongoing war in Ukraine, therefore we offer a 100€ discount for affected individuals and teams affiliated with Ukrainian institutions. In other words, the fees would be 50€ and 0€ per person for onsite and online participation correspondingly.

The expected starting time for the contests is 10am CEST. For online participants, it is still a preferred starting time, but we will make accommodations for other starting times.

Most of our contests are fresh and developed for this camp. A small number of contests may be based on previous contests that have not been released to the general public. If you have seen some problems of a contest before, you can't participate on that day (and your participation fee will be reduced accordingly). We will privately contact participants who might be affected. Based on feedback, we will have a silence period until the end of November 2023, during which camp materials will not be released to the public. Therefore, we ask participants to not discuss the problems in public until that date.


If you are interested in participating, please fill the form here.

We ask you to register before September 8 if you want to participate online and before September 2 if you want to participate onsite.

Also, if your university or organization has a lively ICPC community that may be interested in attending the camp, and you have some contacts of people in charge (e.g. coaches) we would highly appreciate if you could fill the form here, so that we can send an invitation. Thanks!


We'd like to thank and praise the authors of the contests in the camp, including:

  • jeroenodb — Codeforces International Grandmaster, Computational geometry enjoyer. NWERC 2021 and 2022 bronze medalist.
  • fwitt — POI silver medalist.
  • Adam_GS — BOI 2023 winner, EJOI 2021 gold medalist, Codeforces International Grandmaster, problemsetter for OCPC 2023 winter.
  • Asymmetry — IOI silver medalist, CEOI and BOI gold and two times POI gold medalist. CERC 2022 gold medalist.
  • ppavic — triple IOI gold medalist.
  • dorijanlendvaj — double IOI gold medalist, Codeforces Legendary Grandmaster.
  • jtnydv25 — author of over 50 problems.
  • Claris — ICPC 2017 and 2018 world finalist.
  • -is-this-fft- — ICPC 2019 world finalist, Google Hash Code 2020 finalist.

...and others. We would also like to thank Um_nik and nor for their help with reviewing problem proposals.

You can find more details about contest rules and technical setup on the website.


Last but not least, we would like to say special thanks to our sponsors, who make the camp possible. If you are interested in sponsoring next editions of the camp or have any questions, please feel free to reach out at ocpc (at) mathos (dot) hr.

Finally, we would also like to thank Codeforces for guidance and promoting this announcement to the main page, eolymp for providing us an online judge for the contests and the Department of Mathematics at J. J. Strossmayer University of Osijek for all their organizational support and providing us a physical location to conduct the camp.

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By SlavicG, history, 2 months ago, In English

Hello Codeforces!

mesanu, flamestorm and I are very excited to invite you to Codeforces Round 886 (Div. 4)! It starts on Jul/21/2023 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.

Many thanks to all testers: MikeMirzayanov, erekle, Bakry, Dominater069, Gheal, andrei_boaca, zwezdinv, sam571128, Sho, Wibo, Phantom_Performer, notyourbae, mafailure, Kalashnikov, SashaT9, Qualified, haochenkang, ZiadEl-Gafy, MADE_IN_HEAVEN, AdOjis485, mister, mkisic, SmartCoder, sabbir-hasan-anik, peshkoff, donghoony!

And thanks to Vladosiya for translating the statements!

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

Good Luck to everyone!

UPD: Editorial is out!

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By diskoteka, 2 months ago, In English

(っ▀¯▀)つ Heeey Codeforces (っ▀¯▀)つ

I and pavlekn are glad to invite everyone to participate in Codeforces Round 885 (Div. 2). The round will take place on Jul/16/2023 17:35 (Moscow time).

This round is dedicated to an amazingly beautiful girl Vika that I love very much. Every problem will be about her and related to her life.

The 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.

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

  1. Artyom123 for coordinating the round

  2. MikeMirzayanov for great Polygon and Codeforces platforms

  3. teraqqq, Be_dos, mibig, FairyWinx, princebelkovetz for red testing

  4. Dominater069, mbolgov, I.Gleb, induk_v_tsiane, Alexdat2000, maomao90, irkstepanov, fishy15 for yellow testing

  5. Serik2003, alwyn for blue testing

  6. TkachDan, ak2006 for cyan testing

  7. maksimb2008 for grey testing

Scoring distribution: 500 — 1000 — 1500 — 2000 — 2250 — 2750.

We wish you all good luck and a high rating!

UPD: Editorial published

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