By applepi216, 3 days ago, In English

Hello Codeforces!

I am glad to invite you to Codeforces Round 986 (Div. 2), which will start on Nov/10/2024 18:35 (Moscow time). Note the slightly unusual start time.

The contest will run for 2 hours and have 6 tasks. The contest will only be rated for those with a rating not higher than 2099, but we welcome higher rated users to participate out of competition.

Holding the contest would have been impossible without:

and of course a special thank you to all of you for participating!

Score Distribution: $$$500-1000-1500-1750-2000-2500$$$.'

UPD: The Editorial is now published.

UPD2: Congratulations to the winners!

Div 1:

  1. jiangly
  2. A_G
  3. BurnedChicken
  4. MAKMED1337
  5. maspy

Div 2:

  1. SUPERLWR-beta
  2. mychecksdead
  3. sweet_dream
  4. contee
  5. Sunflower233

First solves:

Full text and comments »

  • Vote: I like it
  • +143
  • Vote: I do not like it

By sszcdjr, history, 5 weeks ago, In English

Hello, Codeforces!

We (KDOI Team) are glad to invite you to take part in Refact.ai Match 1 (Codeforces Round 985), which is the 8th CP contest held by us! You can view the previous rounds by us here.

  • Number of problems: $$$9$$$ ($$$0$$$ interactive);
  • Start time: Nov/09/2024 17:35 (Moscow time);
  • Contest duration: $$$180$$$ minutes;
  • Score distribution: $$$750-1250-1750-2250-2500-3000-3500-5000-5500$$$.

The problems were authored and prepared by Error_Yuan, wyrqwq, Otomachi_Una and me sszcdjr.


A few words from our sponsor:

We’re Refact.ai, an open-source AI Coding Assistant, and on November 9th, we’ll be hosting our first round on Codeforces! Winners will receive valuable prizes, and all participants will have a chance to get some exclusive merch from us.

Refact.ai is pushing AI beyond simple code completion. Soon, we’ll launch the Autonomous AI Agent—a developer’s buddy that handles real engineering tasks end-to-end, from planning and coding to testing and deployment. You can read more about us in this announcement.

If you're excited about AI in software development and want to build the future instead of focusing on the trivial, join Refact.ai, founded by a former OpenAI researcher. We’re looking for talented Researchers and Backend developers to join our team.

Apply

Prizes:

  • 1st place: 500 USDT
  • 2nd place: 300 USDT
  • 3rd place: 200 USDT
  • 4-5th place: 100 USDT
  • Top 50 participants will get T-Shirts
  • Additionally, 50 random participants from the top 51-500 will receive a T-shirt

Good luck in the contest!


On the right, badges of the authors. From top to bottom, left to right are Error_Yuan, Otomachi_Una, sszcdjr and wyrqwq respectively.

We would like to thank:

Good Luck & Have Fun!

UPD1. The Editorial was published.

UPD2. Congratulations to the winners!

  1. Benq
  2. jiangly
  3. hos.lyric
  4. Radewoosh
  5. arvindf232
  6. Nachia
  7. ksun48
  8. Szoboszlai10
  9. Endagorion
  10. _Serge_

Full text and comments »

  • Vote: I like it
  • +638
  • Vote: I do not like it

By JetBrains, history, 6 days ago, In English

Hello Codeforces!

Hello Codeforces! As we wrap up another exciting round of our Kotlin Heroes series, it’s time to celebrate the champions who navigated the challenges like pros. With high stakes and impressive typing speeds, we witnessed incredible talent. Join us as we highlight the winners!

The top three contestants:

  1. arvindf232
  2. tourist
  3. Golovanov399

A Kotlin Heroes T-shirt and exclusive Kotlin stickers will be presented to:

These participants also won branded T-shirts:

We will contact the winners soon to coordinate the delivery of their prizes!

It's great to see new people learning Kotlin and performing brilliantly in the competition. Challenges from all eleven previous rounds are available for practice here: Episode 1, Episode 2, Episode 3, Episode 4, Episode 5: ICPC Round, Episode 6, Episode 7, Episode 8, Episode 9, Episode 10 and Episode 11.

For those who would like to get to know Kotlin better, take a look at Basic Kotlin (solve Koans), Kotlin Playground, this competitive programming tutorial, and these videos on competitive programming in Kotlin.

We wish you luck and hope you enjoy Kotlin!

Full text and comments »

  • Vote: I like it
  • +62
  • Vote: I do not like it

By refactai, history, 8 days ago, In English

Hello, Codeforces.

We're Refact.ai, an open-source AI Coding Assistant, and on November 9th, we'll be hosting our first round on Codeforces! It will be a combined Div.1+Div.2 round. Welcome!

The winners will receive valuable prizes, and all participants will have a chance to get some exclusive merch from us.

Refact.ai is pushing AI beyond simple code completion. Soon, we'll launch the Autonomous AI Agent—a developer's buddy that handles real engineering tasks end-to-end, from planning and coding to testing and deployment.

If you're excited about AI in software development and want to build the future instead of focusing on the trivial, join Refact.ai, founded by a former OpenAI researcher. We're looking for talented Researchers and Backend developers to join our team.

We already have competitive programmers on board, such as humbertoyusta and Rox. As humbertoyusta puts it, "Working at Refact.ai feels like being part of a team that's constantly pushing the boundaries of what's possible." If that sounds like your kind of environment, fill out this form for full-time positions (remote or in Barcelona).

If you're not open to new job opportunities but want to delegate tedious tasks and climb the leaderboard faster, explore: Refact.ai — an Open-source AI Coding Assistant that helps you create more while coding less.

Refact.ai already empowers you to code smarter. How?

  • Built around your codebase, it provides accurate auto-completions powered by best-on-market Retrieval-Augmented Generation (RAG).
  • Integrated in the IDE chat is already aware of your codebase and answers your questions right within your editor. (Compare it with Copilot and see the real power:)
  • Detects and fixes bugs, writes unit tests, explains complex code, and much more!

Assign tasks in natural language, select from models like GPT-4o, GPT-4 Turbo, Claude 3.5 Sonnet, or Grow-Llama-3.1, and Refact.ai will generate the code for you.

  • Get 3 months of the Pro Plan for free: Refact.ai has a special gift for the Codeforces community. Just use the promo code CODEFORCES to redeem it.

  • Join the Discord community: Collaborate with like-minded developers and discuss the latest news and research.

  • Contribute to Refact.ai: As an open-source project, Refact.ai welcomes your contributions—join us in building the future of programming together!

We hope you enjoy the problems and have a great time participating in the round!

Full text and comments »

  • Vote: I like it
  • +365
  • Vote: I do not like it

By m3tr0, 11 days ago, translation, In English

Hi Codeforces!

We would like to invite you to participate in Codeforces Round 984 (Div. 3) on Nov/02/2024 17:35 (Moscow time). You will be given 7 problems and 2 hours and 15 minutes to solve them. The penalty for an incorrect submission will be 10 minutes. There may be interactive problems in the round.

The round will be ruled according to the standards of educational rounds (extended ICPC). Thus, solutions will be judged on preliminary tests during the round, and after the round, there will be a 12-hour phase of open hacks. After open hacks all accepted solutions will be rejudged on successful hacks. We've tried to make decent tests — just like you, we'll be upset if you have dropped solutions after the end of the contest.

Reminder that only trusted Division 3 competitors will be included in the official results table. This is a forced measure to combat unsportsmanlike behavior. To qualify as a trusted Division 3 competitor, one must:

  • participate in at least five rating rounds (and solve at least one problem in each of them)
  • not have a point 1900 or higher in the rating.

Whether you are a trusted Division 3 participant or not, if your rating is less than 1600, the round for you will be rated.

The tasks were authored and prepared by a team consisting of Seny, eugenechka.boyko.2_0-0 and myself.

The round is based on the recent Lipetsk Team Programming Olympiad for school students. Please note that if you are a participant of the Olympiad, you are not allowed to participate in this round. Thanks to the coordinator of this Olympiad myav and the author Small_machine, whose tasks were not included in this round due to their high complexity.

We thank very much:

We hope you find the problems interesting. Good luck!

UPD.: Editorial

Full text and comments »

  • Vote: I like it
  • +76
  • Vote: I do not like it

By Sagita_Phoenix, history, 3 weeks ago, In English

Hello Codeforces!

$$$\newline$$$

From AkiLotus

It's been a while, today AkiLotus and I are delighted to invite you to participate in Codeforces Round 983 (Div. 2). This round will be rated for all participants with a rating lower than 2100.

Our round will start on Nov/01/2024 17:35 (Moscow time). You will be given 6 problems and 120 minutes to solve them.

This contest is a collaboration between AkiLotus, his friends and Code Mely, a Vietnamese community and an individual passionate about Computer Science. Reach out to us here.

Special thanks to:

$$$\newline$$$

Score distribution: $$$500 - 750 - 1250 - 1750 - 2250 - 3000$$$

Happy coding! Our chicken nuggets and Fubao bless you.

UPD1: Editorial is published.

UPD2: Congratulations to the winners!

Div. 1 + Div. 2:

  1. Nachia
  2. arvindf232
  3. peti1234
  4. turmax
  5. superguymj
  6. Rubikun
  7. ksun48
  8. potato167
  9. BurnedChicken
  10. Vincella

Div. 2 (official):

  1. Vincella
  2. SUPERLWR-beta
  3. BlackLily
  4. leolin0214
  5. TAIYANGFENG
  6. xiaowangba
  7. piasticOuO
  8. Nikephoros2Phocas
  9. SkyWave2024
  10. zsj6315

First solves:

Full text and comments »

  • Vote: I like it
  • +429
  • Vote: I do not like it

By awoo, history, 2 weeks ago, translation, In English

Neapolis University Pafos

Hello Codeforces!

The series of Educational Rounds continues thanks to the support of the Neapolis University Pafos. They offer a BSc in Computer Science and AI with JetBrains Scholarships. Gain cutting-edge skills in AI and machine learning, preparing you for high-demand tech careers. Curious? Join the livestream on Tuesday, October 29 at 5:00 pm UTC to learn about the CSAI program’s curriculum, course structure, scholarships, student internships, and their hands-on learning approach.

Want more experience in coding and math competitions?
JetBrains Youth Challenge returns in November 2024!

Who can join?
Ages 13–18
Anyone currently enrolled in secondary education
Register now

On Oct/28/2024 17:35 (Moscow time) Educational Codeforces Round 171 (Rated for Div. 2) will start.

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, 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!

UPD: Editorial is out

Full text and comments »

  • Vote: I like it
  • +46
  • Vote: I do not like it

By Hori, 6 weeks ago, In English

Hello, Codeforces!

We are pleased to announce the resumption of the Global Rounds. Thanks to XTX Markets for supporting the initiative! In 2024, we will hold 4 such rounds. The series results will take into account the best 3 participations out of 4.

On Oct/27/2024 17:35 (Moscow time) we will host Codeforces Global Round 27.

Codeforces Global Round 27 marks the third round in the 2024 series of Codeforces Global Rounds. These rounds are open and rated for everyone.

The prizes for this round are as follows:

  • The top 30 participants will receive a t-shirt.
  • 20 t-shirts will be randomly distributed among participants ranked between 31 and 500, inclusive.

The prizes for the 4-round series in 2024:

  • In each round, the top-100 participants get points according to the table.
  • A participant's final score will be the sum of the points they earned in their 3 highest-placing rounds.
  • The top 20 participants across the series will receive sweatshirts and placement certificates.

We extend our gratitude to XTX Markets for supporting the global rounds initiative in 2024!

The 8 problems were authored by our 8 authors: Benq, lunchbox, oursaco, sum, willy108, Hori, turtletortles, and last but not least ChatGPT.

We would also like to thank:

Round Information:

  • Duration: 180 minutes
  • Number of problems: 8 problems with 1 subtask
  • Score distribution: 250 — 500 — 1000 — 1500 — 2000 — 2250 — (2250 — 2000) — 4500

We look forward to your participation!

UPD: Congrats to the winners

  1. Kevin114514
  2. 275307894a
  3. jiangly
  4. JoesSR
  5. ksun48
  6. turmax
  7. dXqwq
  8. hos.lyric
  9. Rewinding
  10. jiangbowen

UPD2: First solves

A: dXqwq
B: hos.lyric
C: dorijanlendvaj
D: riantkb
E: turmax
F: taeyeon_ss
G1: taeyeon_ss
G2: Kevin114514
H: orz (only in contest solve!)

UPD3: Editorial

Full text and comments »

Announcement of Codeforces Global Round 27
  • Vote: I like it
  • +467
  • Vote: I do not like it

By myst-6, history, 3 weeks ago, In English

Hello Codeforces! Me and yud08 are excited to invite you to take part in Codeforces Round 982 (Div. 2), which starts on Oct/26/2024 17:35 (Moscow time). You will be given 5 problems and 2 hours to solve them. Two problems are divided into two subtasks.

This round will be rated for all participants whose rating is strictly below 2100.

The problems were authored by me and yud08, and prepared by me.

We would like to thank:

We hope you enjoy the problems!

Score Distribution: $$$500 - 1000 - 1250 - (1250 + 1000) - (2000 + 1000)$$$

We actually wanted to continue the trend of posting photos of contest writers, but we could only find one photo containing both of us, which was a group photo that we took with some other UK informatics people! (I'm the one in the back of the picture who is wearing the MHC T-shirt and yud08 is the one whose head is popping out from the left side of the photo.)

20240921-153321

UPD1: Congratulations to the winners of the contests:

Div 1:

  1. jiangly
  2. neal
  3. SSerxhs
  4. A_G
  5. kotatsugame

Div 2:

  1. nathan_higgs
  2. purupurupururin
  3. Nonoze
  4. Hong_Meiling
  5. Nika_Tamliani

Also, first solves! (if any of these are wrong please let me know)

UPD2: Editorial is available here

Full text and comments »

  • Vote: I like it
  • +492
  • Vote: I do not like it