Hello! Codeforces Round 925 (Div. 3) will start at Feb/13/2024 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.

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

We would like to thank:

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

2. nigus for red testing.

3. vladmart, Gheal, KseniaShk for yellow testing.

4. htetgm for purple testing.

5. natalina, SashaT9, lockdown, bma20006 for blue testing.

6. RedDreams for cyan testing.

7. the_Incharge, Aurora__, Longqiang for green testing

Good luck!

P.S. Happy Valentine's Day!

UPD: Let's continue streak of announces with photo of the authors :)

UPD2: Editorial

Hello, Codeforces! We're glad to invite you to take part in Codeforces Round 924 (Div. 2), which will start on Feb/11/2024 12:35 (Moscow time). You will be given 6 problems and 2 hours to solve them.

This round will be rated for participants whose rating is below 2100. Participants with higher rating can participate unofficially.

The problems were authored and prepared by vaaven, silvvasil, Alexdat2000, teraqqq and me.

The round is based on Moscow Olympiad for school students.

We would like to thank

• TheScrasse for his high-speed coordination;
• nor, Wizard_of_Orz, GreatEagle, rolandpetrean, volochai, A_G, Wobert, --tofu--, -is-this-fft-, jamesbamber, franv, MatteoArcari, sum, rayban, Be11T_, sashastrakhal, ihavenoenemies and cowgirl for testing;
• MikeMirzayanov for creating Codeforces and Polygon.

Score distribution: $$$500 - 1000 - 1500 - 1750 - 2250 - 2750$$$

UPD: Editorial

UPD2: Congratulations to the winners!

Div. 2

1. hmmmmm

2. satellite.

3. RomkaRS

4. Alx

5. hirayuu_cf

Div. 1

1. SSRS_

2. maspy

3. kotatsugame

4. 74TrAkToR

5. SSerxhs

Gamarjoba, Codeforces!

On Feb/06/2024 17:45 (Moscow time) will start Codeforces Round 923 (Div. 3), the next Codeforces round for the Div.3.

Lately, I've been coming up with problem ideas less frequently, but I don't want to lose this skill. Welcome to the round where all problems are my own creation! I hope you'll enjoy them.

A huge thank you to Vladosiya for preparing the majority of problems in Polygon. Also, thanks to pashka and KAN for helping with the discussion of problem ideas.

Thank you very much 74TrAkToR, CLown1331, EternalAlexander, Jostic11, Killever, KoT_OsKaR, LoveWX, MADE_IN_HEAVEN, dan_dolmatov, jnmtz111__, pedrolino, theRealChainman, yorky for testing the round.

As usual for the Div.3 rounds:

• There will be 6-8 tasks in a round.
• The round duration is 2 hours and 15 minutes.
• The round follows the ICPC rules, with a penalty for an incorrect submission being 10 minutes.
• The round is rated for participants with ratings up to 1600.
• After the round, there will be a 12-hour open hacking phase.

Remember that only the trusted participants of the Div.3 will be included in the official standings table. As it is written in the link, this is a compulsory measure to combat unsporting behavior. To qualify as a trusted participant of the third division, you must:

• Participate in at least five rated rounds (and solve at least one problem in each of them).
• Not have a rating of 1900 or higher.

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.

Good luck to all!

I really like it when the round announcement includes a photo of the authors. I plan to add one if I can take a suitable photo.

UPD 1: I found great burgers in Tbilisi!

UPD 2: The editorial is published: https://codeforces.net/blog/entry/125597 (thank you, Vladosiya).

Hello, Codeforces.

Let's recall 2023, shall we?

In this post, I want to summarize this year. You know, a lot of terrible things happen in the world, and personally, this year was the hardest and most sorrowful for me. But today, we'll remember something else. We'll remember what this year was like for Codeforces.

Recently, Codeforces turned 14 years old. Not bad, right? And for many years now, when asked "What is Codeforces?" the first thing I say is — it's a community!

Greetings Codeforces community!

We are excited to announce the Constructor Open Cup 2024, our annual online programming competition organized by Constructor University and JetBrains.

What is the Constructor Open Cup 2023?

Constructor Open Cup is an online contest organized by Constructor University and JetBrains, the global leading tool provider for developers, to promote interest in computer science, data science, software development, and software engineering.

Put your knowledge and skills to the test in this 4-hour competition and stand a chance to walk away with a scholarship for a bachelor's degree in Software, Data and Technology (BSc SDT) at Constructor University, Germany’s #1 private university*!

Constructor Open Cup timetable

February 1-7, 2024 | Practice Round

Get familiar with the testing environment during this practice round.

February 8, 2024 at 2 PM (UTC) |Main Round

You will have 4 hours to complete a series of algorithmic programming tasks. Registration closes 1 hour before the start of the contest.

Prizes and Winner Announcement

The top candidates will receive exciting prizes, including:

• chance to get scholarships for the BSc SDT*
• exciting memorable gifts from Constructor University and JetBrains

*The winners who applied to the BSc SDT will receive an email to schedule the interview with Constructor University and JetBrains.

What do participants say?

“I was just surfing Codeforces blogs when I found a post about the Constructor Open Cup 2023. After discovering that I could have a chance to win a scholarship from JetBrains, I registered for the competition and placed among the top 20-30. The contest itself was very interesting, with different types of problems that allowed me to showcase my knowledge. I felt very honoured to receive a scholarship, and now I am one of the students in the BSc SDT program” – IMRUN, BSc SDT first-year student.

How can I participate?

• Register your details on the webpage.
• Finalize your registration at Codeforces using the link you receive in the confirmation email.
• If you have any further queries, please reach out to [email protected].

Can I participate?

Everyone is welcome! The contest is open for all ages and skill levels, all you need is a passion for coding.

To get the chance for the scholarship for BSc SDT, please check Constructor University’s eligibility requirements.

About the BSc SDT program

This program prepares talents to become tomorrow’s elites in software development, programming languages, data analysis, and machine learning. You will benefit from the latest insights and knowledge from top industry partners and get the right skills needed for these rapidly changing industries. Learn more about the program here.

About Constructor University

Founded in 2001 as a private, English-language campus university, it repeatedly achieves top results in national and international university rankings. Constructor University aims to transcend the traditional academic approach by combining educational fundamentals with project-based pedagogy and the latest in digital tools. It equips the young professional elites with the right skills and knowledge to address today's challenges and thrive in the job market.

About JetBrains

JetBrains is a global software company that creates professional software development tools and advanced collaboration solutions trusted by more than 15 million users worldwide. Since 2000, we have built a product catalogue that covers all stages of the software development cycle, major technologies, programming languages, and educational processes.

The product range includes award-winning tools, such as IntelliJ IDEA, PyCharm, ReSharper, and PhpStorm, and productivity-enhancing team tools like YouTrack, TeamCity, and Datalore. JetBrains is the creator of Kotlin, the officially preferred language for Android™ development.

For more information, please visit the webpage.

Hello, Codeforces!

I and ooaa are excited to invite you to participate in Codeforces Round 922 (Div. 2), which will take place on Jan/30/2024 17:35 (Moscow time).

This round will be rated for participants, whose rating is below 2100. Participants with higher rating can participate unofficially.

You will be given 7-8 problems and 2 hours to solve them. We recommend you to read all the problems. 1 or more interactive problems may occur in the round, so we suggest to read this post.

We would like to thank:

• Akulyat for the excellent coordination of our round.
• wuhudsm for finding that the previous C has already occured in one of the rounds.
• A_G, bashkort, orz, Andreasyan, green_gold_dog, zwezdinv, EJIC_B_KEDAX, Kihihihi, makrav, sam571128, Undying, htetgm, wuhudsm, kovir_aleksey_korroy, JustNik77, Chaska, Murinh0, leoper and Ileonov for testing and valuable feedback.
• MikeMirzayanov and geranazavr555 for the excellent Codeforces and Polygon platforms.
• You, for participating in this round.

We wish you good luck and high rating!

UPD. Score distribution: $$$500 - 1000 - 1250 - 2000 - 2500 - 3000 - 3250$$$.

UPD2. Congratulations to the winners!

Div. 2

1. alice_ssoi

2. JaredGoff

3. ppltn

4. sunc_mgu_govno

5. 1926_yes

Div. 1+2

1. arvindf232

2. SSerxhs

3. alice_ssoi

4. natofp

5. JaredGoff

Congratulations to the first solves as well!

• А. EyadBT
• B. __jk__
• C. Golovanov399
• D. thisisnotaclone
• E. WLZ
• F. tute7627
• G. wsyear

UPD3. Editorial.

Hi Everyone :)

I would like to invite you to my first Codeforces Round, which I set with my friends JaySharma1048576 and mexomerf — Codeforces Round 921 (Div. 1) and Codeforces Round 921 (Div. 2) which will be held on Jan/27/2024 17:45 (Moscow time). This round will be rated for both divisions.

Both divisions will be given 6 problems and 2 hours to solve them.

One of the problems may be interactive. So, you are advised to refer to the guide on interactive problems in case you are not familiar with them.

We would really like to thank:

• Aleks5d for coordinating our round.
• jtnydv25, dario2994, IceKnight1093, oursaco, satyam343, Riladavin, magga, peltorator, _Enigma__, Makcum888, MisterReaper, htetgm, 18o3, sezal, alwyn, somplz, nor and kevinsogo for testing and improving the problems.
• abhidot for listening to our problems even before we proposed them.
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• You for participating.

Good luck, have fun!

UPD: Scoring Distribution

Div. 1: $$$500 - 1000 - 1500 - 1750 - 2500 - 3000$$$
Div. 2: $$$500 - 1000 - 1250 - 1750 - 2500 - 3000$$$

UPD: Here is the editorial

UPD: Congratulations to the winners

Div. 1:

1. jiangly
2. maroonrk
3. Benq
4. gamegame
5. maspy

Div. 2:

1. kto_eto
2. fractum_locum
3. okok
4. beiyuli
5. BabaVoss

First solves -

Div. 2:

Div. 1:

Hello, Codeforces!

If you're developing problems in Polygon, you might like this image to attract attention.

For the new members of the community, I would like to remind you that Polygon (https://polygon.codeforces.com/) is a system developed and maintained by Codeforces for preparing programming problems. It is there that authors and coordinators develop all the problems for the rounds. Moreover, I believe a significant (large?) portion of the problems for other competitions is also developed there: various stages of ICPC, national competitions of different levels, educational problems for various courses, etc. In 2023, more than 50000 problems were prepared in Polygon (only those for which a package was compiled are counted)!

We often implement such improvements in Polygon that make the process of preparing a problem more reliable. These often include various automatic warnings and tips for problem developers and/or coordinators.

Today I want to talk about two recent such innovations in Polygon.

Hello Codeforces!

On Jan/18/2024 17:35 (Moscow time) Educational Codeforces Round 161 (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, Ivan BledDest Androsov, Maksim Neon Mescheryakov, Roman Roms Glazov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

Big thanks to the testers shnirelman and Minder for their valuable advice and suggestions!

Good luck to all the participants!

UPD: Editorial is out