By Aksenov239, history, 3 days ago, In English

Hello everybody!

After a long break I would like to announce the fourth Bioinformatics contest organized by ITMO University, Bioinformatics Institute, Rosalind and Stepik. The contest is sponsored by JetBrains, Yandex, Serokell, and Genotek.

The contest is hosted on Stepik platform. To participate you have to sign the rules.

The contest consists of two rounds:

The contest is prepared by the following team: Alexey Sergushichev, Nikita Alexeev, Nebuchadnezzar, demon1999, tourist, cdkrot, GShark, doreshnikov (all ITMO University), German Demidov (Center for Genomic Regulation), Andrey Prjibelski (CAB SPbU).

Are there any prizes?

  • 1st place – Whole Genome Sequencing
  • 2nd and 3rd – Whole Exome Sequencing
  • 4th and 5th – 23andMe or Genotek DNA Service
  • 1st–30th – Honorable Bioinformatics T-Shirt

Do I need to know biology?

The knowledge of biology is not necessary to solve the problems!

We wish that you will like the problems!

Good luck!

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By Dormi, 5 days ago, In English

Hello, Codeforces!

Welcome to the Codeforces LATOKEN Round 1 (Div. 1 + Div. 2) supported by LATOKEN, that will start on Jun/13/2021 18:35 (Moscow time). It will be a combined rated round for both divisions (and div 3). Please, note the unusual start time.

All problems were created by Aaeria, crackersamdjam, Dormi, Ninjaclasher, and Plasmatic.

We would like to thank:

You will be given 8 problems and 180 minutes to solve them. This contest features at least one interactive problem, so we recommend reading the guide of interactive problems before the contest.

We hope that statements are short and pretests are strong and that you find the problems interesting! Good luck, have fun, and we wish everyone high ratings!

The scoring distribution will be announced closer to the beginning of the round.

Thanks to LATOKEN, winners will get awesome swag:

  • 1st place = MacBook Air M1 + Job offering and Stock Options
  • 2nd place = Xiaomi Mi 11 + Job offering and Stock Options
  • 3rd place = Xiaomi Mi Notebook Pro 15" Enhanced Edition + Job offering and Stock Options
  • 4th-10th place = Job offering and Stock Options + Merchandise Pack
  • 11th-55th place = Merchandise Pack

Random 10 participants outside of top-55, who solved at least one problem and participated in rated Codeforces rounds before, will get a t-shirt!

A few words from the LATOKEN team:

We welcome you to the intellectual battle between the best coders from around the world! LATOKEN strives to make trading crypto as easy as having a social media account. We are always looking for the best of the best to join our team. As a result, LATOKEN is currently in Coingecko’s Top 15 with over 600 000 app installs within just one year from its launch and 1m+ users in total. The emerging blockchain based financial systems will open exciting opportunities, because crypto is fully global and mostly independent of conservative banks.

If you want to become a part of something bigger, work remotely with a team of international professionals and change the world, contact our recruiters for internships and employment opportunities in the LATOKEN team. Use our bot or fill out the form below and tell us a little about yourself.

Contact Form →

UPD: The scoring distribution is 500 — 1000 — 1250 — 1500 — 2250 — (1750 — 1250) — 3250 — 3500.

UPD: Editorial

Congratulations to the winners:

  1. Benq
  2. tourist
  3. Radewoosh
  4. Endagorion
  5. ecnerwala
  6. heno239
  7. peehs_moorhsum
  8. gamegame
  9. Pyqe
  10. maroonrk

The prizes will be distributed in the next few days after we remove cheaters.

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By Stepavly, 6 days ago, translation, In English

Hello, Codeforces!

UPD: Since the round seems a little more complicated than usual after testing, we extended the round length by 15 minutes.


Hello! Codeforces Round #725 (Div. 3) will start at Jun/10/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended 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 7 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 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.

The problems for this round were invented by MikeMirzayanov, Supermagzzz and Stepavly.

Thanks to Fly_37, -is-this-fft-, A_Le_K, ALILILILILI-KHAN, ANZ1217, hocky, PhaiCoGiaiQuocGia, Sho, ASIXER, songsinger, OlegZubkov, AlexFetisov, darkkcyan, ivanzuki, kocko, Gassa for help with testing the round.

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!


UPD: Editorial

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By golions, 11 days ago, In English

Hello Codeforces!

We, the disciples of Omkar (qlf9, Tlatoani, hu_tao, golions, and Omkar's newest disciple, rabaiBomkarBittalBang), have written our third contest: Codeforces Round #724 (Div. 2)Omkar 3. It will be held on Jun/06/2021 17:35 (Moscow time) and will be rated for users in Division 2 (rating lower than 2100). As usual participants with rating >= 2100 are allowed to compete too, but the contest will be unrated for them.

You will be given 2 hours to solve 6 problems. There may or may not be an interactive problem, so it would behoove you to read the guide for interactive problems. There also may or may not be competitive programming problems, so you should be sure to thoroughly understand everything here.

We would like to thank:

The scoring distribution is 500 — 1000 — 1500 — 2000 — 2250 — 2500.

May Omkar be with you!

Update: Thank you for participating in our contest! The editorial is here. We have video editorials for every problem there!


The winners in official standings:

  1. xin_chen

  2. adc-s11-sadge

  3. conqueror_of_rainboy

  4. XOXOX

  5. TwTwTwTwT

The winners in unofficial standings:

  1. neal

  2. Maksim1744

  3. dlalswp25

  4. hank55663

  5. fanache99


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By awoo, history, 12 days ago, translation, In English

Hello Codeforces!

On Jun/04/2021 17:35 (Moscow time) Educational Codeforces Round 110 (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 Roman Roms Glazov, 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:

Codeforces and Harbour.Space

Hey, Codeforces!

Once again, it is time for another exciting scholarship opportunity from Harbour.Space!

If you love technology, enjoy creating, and looking for an exciting career, Front-end Development might be for you! This time we are looking for talented individuals to launch our new programme with.

We are offering up to a 50% scholarship for our Bachelor’s and Master’s degrees, opening the doors for an exciting career in technology for the most talented people in our network.


  1. Diploma and transcript of the highest attained education level
  2. Professional fluency in English
  3. Your CV

What you will learn:

  • Coding up to industry standards
  • Accelerated learning
  • Master new tech frequency
  • Javascript frameworks, CSS preprocessors and methodologies, responsiveness, and also visual design
  • And more

Make sure to apply before June 30, 2021, to be eligible for the scholarship and reduced application fee.

Some of the advantages of studying at Harbour.Space:

  • We change the way of learning
  • We learn by doing
  • We are your home

We are always happy to see Codeforces members join the Harbour.Space family. Apply now to learn from the best in the field and kickstart your career!

Keep in touch and follow us on LinkedIn for more scholarship opportunities. And follow us on Instagram to evidence student life, events, and success stories from students.

Good luck on your round, and see you next time!

Harbour.Space University

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 SSRS_ 6 118
2 Maksim1744 6 137
3 Geothermal 6 147
4 neal 6 154
5 Ormlis 6 167

Congratulations to the best hackers:

Rank Competitor Hack Count
1 Kawaii 51:-7
2 coder_ym_ 28:-3
3 zhuzhirui2005 27:-4
4 DespicableMonkey 21
5 DevilAeron 20:-5
342 successful hacks and 911 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A Geothermal 0:00
B neal 0:02
C Geothermal 0:05
D SSRS_ 0:12
E _runtimeTerror_ 0:18
F xay5421 1:01

UPD: Editorial is out

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By niyaznigmatul, 2 weeks ago, In English

Hi, Codeforces users!

We are announcing ITMO Summer Camp in Competitive Programming that will be held online. On each of the 10 days from June 21 to July 2 (the weekend are the rest days) two-hour lecture and two-hour practice session is going to take place.

Each day one topic is covered, and the practice session is a set of problems of that topic. For lectures we use Zoom, and for practice we use Codeforces. Both will be live, so you can ask questions during the lecture and during the practice, the teacher will help you if you are stuck with your code or didn't get something. The lectures and the problem statements are in English. The school is mostly for Codeforces division 2 and 3 participants. You are required the knowledge of high school math and the ability to code simple programs in C++/Java/Python (or any other language that Codeforces supports, but we are not sure we can help with them).

The main topics are:

  • Sorting and Binary Search
  • Dynamic Programming
  • Graphs, DFS, SCC finding
  • Graphs, Shortest paths, BFS, Dijkstra's algorithm
  • Strings, Prefix-function, Z-function
  • Segment Tree
  • RMQ, LCA, Sparse Table

The main topics will be covered for sure, but other topics on the official website can be changed depending on average level of students.

The cost of participation is 245 Euro. ITMO Official Certificate will be given to the participants.

To apply, visit Application deadline is June, 10, 2021.

If you have any organizational questions (regarding documents, payment, certificates, etc) ask the school manager Ekaterina Rassolenko by emailing to e.rassolenko (at)

UPD: Most probably there will be two learning groups, at different times of day. Current plan is: Morning classes are held from 11:00 to 15:00, evening classes – from 17:00 to 21:00 (GMT +3).

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By deltixlab, 4 weeks ago, translation, In English


Hi Codeforces!

We are DELTIX. Founded in 2005, DELTIX is one of the market leaders in software development for financial research and products for systematic and algorithmic trading. In 2020 DELTIX joined the EPAM family. Our mission is to turn promising ideas into breakthrough products fast.

We are experts in:

  • aggregation, storage, and processing large volumes of time-series data
  • data modeling
  • testing and deployment of quantitative models

In our team we value skills like:

  • knowledge of algorithms
  • high-performance coding
  • low latency data streams processing

Learn more about DELTIX

Throughout the year, once per quarter, we will be inviting you to join DELTIX rounds at Codeforces. Today, we are excited to welcome you to the first installment of our rounds (joined Div1 и Div2) — Deltix Round, Spring 2021 (open for everyone, rated, Div. 1 + Div. 2), that will start on May/30/2021 17:35 (Moscow time).

It is an open and rated round for both divisions.

We have prepared the following trophies for you:

  • 1st place = the most desired console of 2021 — PlayStation 5!
  • 2nd place = Nintendo Switch
  • 3rd place = Nintendo Switch Lite
  • 1-100: branded t-shirts

Another 100 t-shirts will be distributed randomly between 100 participants outside of top-100 and who have solved at least one problem and participated in rated Codeforces rounds before.

Problems have been prepared by our employees: Vladik, netman, AleXman111 and sdryapko.

We would like to say a word of appreciation:

We will offer participants 8 problems and 135 minutes to solve them. We wish everybody good luck and high ratings!

Fill out a short contact form if you are interested in internship and/or employment opportunities or would like to speak with recruiters or members of our team.

Contact Form →

UPD: The scoring distribution is 500 — 1000 — 1500 — 2250 — 2250 — 3000 — 3250 — 3250.

Thank you all for participating! (editorial)

Congratulations to the winners:
1. tourist
2. Radewoosh
3. Um_nik
4. maroonrk
5. ecnerwala
6. jiangly
7. SSRS_
8. Petr
9. scott_wu
10. Maksim1744

We would like to express our special congratulations to the top three leaders! We will try to send you your well-deserved prizes as soon as possible :) Unfortunately, we can not list the people who received 100 random T-shirts due to the fact that the search for cheaters is not completed.

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By errorgorn, history, 3 weeks ago, In English

Hello again Codeforces!

errorgorn, oolimry and iLoveIOI are glad to invite you to participate in Codeforces Round #723 (Div. 2) which will be held at May/28/2021 17:05 (Moscow time). The round will be rated for the participants with a rating lower than 2100. Participants from the first division are also welcomed to take part in the competition but it will be unrated for them.

You will be given 2 hours and 30 minutes to solve 6 questions. One of the puzzles is interactive, please read the guide of interactive problems before the contest.

We would like to thank:

We hope you find the bugaboos interesting and fun! Wish you high rating!

Here is scoring distribution because you guys deserve it <3

  • 500 — 1000 — (750+1000) — 2250 — 2500 — 3500

Btw, remember to downvote all testers who writes stupid comments to beg for likes.

UPD: editorial released

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