By MikeMirzayanov, 4 months ago, In English

Hello.

Today I removed the account zh0ukangyang from the rating, after first nullifying its results in the Pinely Round 3 (Div. 1 + Div. 2) and banning it.

I would like to remind you again: Codeforces insists on the policy of using a single account. Creating and using additional accounts violates this rule. In an ideal world, each Codeforces account corresponds to one specific person.

Sometimes additional accounts are created for official, usually collective purposes (writing a post on behalf of a company, etc.). In such cases, these accounts do not participate in rated rounds and we do not pay attention to them unless there is some abuse of Codeforces resources.

Unfortunately, it is difficult for us to enforce this rule in almost all cases. But I urge you to respect the rules. Please remember that by registering for any rated contest, you confirm that you are participating with your only account. If this is not the case, then you are violating the community rules. Do not do this. By breaking the rules, you automatically agree that punishment may be applied to you.

In cases where rule violations significantly affect the ratings of other participants, we may take drastic measures. Remember, with great power comes great responsibility.

In this case, zh0ukangyang was at the top of the ratings, occupying high places in the rounds.

What should you do if you already have several accounts and want to stop breaking the rules? You should not write to us with a request to delete accounts or transfer data from one account to another. All you need to do is simply stop participating from all accounts except one. Change the password to a random one and do not log into the account anymore.

For participants at the very top (somewhere in the top 50 of the ratings), we are ready to manually deal with the situation and exclude illegal accounts from the rating.

M.

Full text and comments »

  • Vote: I like it
  • +119
  • Vote: I do not like it

By maomao90, history, 4 months ago, In English

Hello Codeforces,

We are very glad to invite you to participate in Hello 2024, which will start on Jan/06/2024 17:35 (Moscow time). You will be given 8 problems and 2.5 hours to solve them. One of the problems will be divided into two subtasks. The round will be rated for everyone. There will be at most 2024 interactive problems, so please read the guide for interactive problems before the contest.

All the problems are written and prepared by me.

Spoiler

We would like to give our sincere thanks to:

The score distribution is $$$250 - 500 - 1000 - 1500 - 2250 - (1500 + 1500) - 4000 - 5000$$$.

Hope everyone will enjoy the round!

Congratulations to the winners!

  1. ecnerwala
  2. ksun48
  3. VivaciousAubergine
  4. gamegame
  5. cnnfls_csy
  6. maroonrk
  7. tourist
  8. Geothermal
  9. kmjp
  10. yosupo

Congratulations to the first solves as well!

UPD: Editorial

Full text and comments »

Announcement of Hello 2024
  • Vote: I like it
  • +2422
  • Vote: I do not like it

By marzipan, 4 months ago, translation, In English

Hello, Codeforces!

I am happy to invite you to our Good Bye 2023, which will be held at Dec/30/2023 17:50 (Moscow time). The round will be rated for all the participants.

The tasks were created and prepared by 74TrAkToR, zwezdinv, OR_LOVe, marzipan, platelet.

We would like to thank everyone who helped us a lot with round preparation:

During the round you will need to solve 8 problems. You will have 2 hours to solve them.

Score distribution: 250—750—1250—1500—2000—2750—3750—(2750+1750)

We wish you good luck and high rating!!!

UPD https://codeforces.com/blog/entry/124060

UPD1:Tutorial was published

Full text and comments »

Announcement of Good Bye 2023
  • Vote: I like it
  • -4617
  • Vote: I do not like it

By SlavicG, 4 months ago, In English

Happy Holidays Codeforces! 🎅

mesanu, flamestorm and I are very excited to invite you to Codeforces Round 918 (Div. 4)! It starts on Dec/28/2023 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.

Special thanks to the VIP testers: AlperenT, KrowSavcik!

Thanks a lot to the testers: Qualified, Kaushal_26, htetgm, MADE_IN_HEAVEN, sandry24, hbarp, Vladosiya, LucaLucaM, Gheal, tvladm, Dominater069, haochenkang, xiaowuc1, pashka, vrintle, BucketPotato!

And many 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 and enjoy the holidays!!! 🎄 🎄 🎄

Full text and comments »

  • Vote: I like it
  • +503
  • Vote: I do not like it

By _LeMur_, 4 months ago, In English

Hi, Codeforces!

I'm glad to invite you to take part in Codeforces Round 917, which will take place on Dec/24/2023 17:35 (Moscow time). Round will be rated for participants with rating less than $$$2100$$$. Participants from the first division can take part out of competition.

There will be $$$6$$$ problems for $$$2$$$ hours. The problems are authored by IgorI, zidder and me.

Part of the problems in this round were in the Yerevan SU 28.1₀.₂₀₂3 Contest. If you participated in it or know at least one problem from it, please refrain from participating in this round.

We would like to thank

Scoring distribution: $$$500 - 1000 - 1500 - 2250 - 2500 - 3000$$$

We hope you'll like the problemset! Good luck and have fun!

UPD 1: Editorial

UPD 2: Congrats to our winners:

  • Div1 + Div2
  1. tourist
  2. Sugar_fan
  3. BurnedChicken
  4. Rubikun
  5. kotatsugame
  • Div2
  1. -Misaka-Mikoto-
  2. _chashuibiao_
  3. needy_and_sorry
  4. Godjob
  5. LordVoIdebug

Full text and comments »

  • Vote: I like it
  • +281
  • Vote: I do not like it

By TheScrasse, 4 months ago, In English

text Ciao, Codeforces! We're glad to invite you to take part in Pinely Round 3 (Div. 1 + Div. 2), which will start on Dec/23/2023 17:35 (Moscow time). You will be given 9 problems and 3 hours to solve them. One of the problems will be divided into two subtasks.

The problems were authored and prepared by me.

Spoiler

We would like to thank

Score distribution: $$$500 - 1000 - 1500 - 2000 - 2500 - (1500 + 1500) - 4000 - 6000 - 6000$$$

We hope you'll like the problemset!

Update 1: the editorial is here.

Update 2: congratulations to the winners!

This round is made possible with the support of Pinely!

Pinely is an algorithmic trading firm, with its main focus set on high-frequency and ultra-low-latency trading. They have offices in Amsterdam, Limassol, Singapore, and Shanghai and are open for job discussions. Pinely is a team of winners, awardees, and medalists of various competitions in respective fields such as ICPC, IMC, HITB PRO CTF, and Google HashCode, etc. They constantly face various challenges such as developing strategies for trading, optimizing trading systems to achieve the lowest latency reactions to various market events, and saving and processing large volumes of historical data.

You can find out more about Pinely on their website or from their employees registered here on Codeforces. If you want to join the Pinely team, please send your CV to [email protected] or fill in the form:

Apply

Prizes: top 30 contestants and 10 random contestants placed 31-100 will receive a branded Pinely hoodie :)

Full text and comments »

  • Vote: I like it
  • +797
  • Vote: I do not like it

By MikeMirzayanov, 4 months ago, In English

Dear Santa Claus. Please make 2024 a happy year, not just that. Please, we all need this.

Hello, 2024!

And we have traditional gifts!

Change Handle Feature

Hurry! Only until the 10th of January, you can change your handle (but only once)! Note that it will be possible to roll back the changes or change the handle again only after a year. Be careful what you wish for.

You can change your handle to the new one that wasn't used before by anybody or which was used by you before. The links to a profile page with an old handle would automatically redirect to the actual profile.

Again, this year if you took part in at least 10 rounds you can request a handle of an inactive participant. It means that the participant should have a period of activity on Codeforces of at most 180 days, this period should be in 2020 or earlier. The inactive participant can't have posted comments, messages, and so on. It can't take part in more than 2 contests. It will be automatically renamed and informed by email. A user has the opportunity to request back his/her handle: in this case, we will roll back the change and return your previous handle to you. If you can't change your handle to another, it means that some requirements don't meet. Please do not ask me to do something with it. Especially, I do not like requests like "this is my second account, I took an interesting handle myself". I'm not Santa Claus.

Talking about handles I always
reminisce the following story. Once a user wrote me the message: "Please change my handle from I_love_Valya to I_love_Sveta, as I no longer love Valya ..."

New Year's Masquerade of Colors and Ranks

The traditional magical tab has appeared in the profile setting. Happy New Year!

Full text and comments »

  • Vote: I like it
  • +686
  • Vote: I do not like it

By MikeMirzayanov, 4 months ago, In English

TON Smart Challenge

Hello, Codeforces!

I'm happy to invite the Codeforces community to join an unusual competition organized by our title sponsor, the TON Foundation.

The competition will revolve around programming smart-contracts in FunC, native to the TON ecosystem. We invite the Codeforces community to participate in this contest and show that they can not only solve algorithmic problems in rounds but also delve into a new and interesting area.

Join the contest and master complex cell manipulations, smart contract storage organization, comment handling, basic cryptography, and the logic of governance smart contracts through problem-solving.

TON Smart Challenge 5 →

The tasks will go live on December 21, and the submission deadline is December 30 at 23:59:59 (UTC+4). To enter the challenge, register via the @smartchallengebot on Telegram. The bot will assist you throughout the registration process and send you notifications with the latest updates, such as the start of the contest or the tasks. The bot will also guide you on submitting your entry as a legitimate participant.

All entries must be submitted via GitHub, and your account must be at least a month old.

For comprehensive instructions on submitting your entries, refer to the official GitHub repository with the challenge tasks, which the bot will provide you on the first day of the contest.

The scoring system is simple. For each solved problem, the participant can earn a maximum of 6 points:

  • Successful solution of the problem = 5 points
  • Gas efficiency of the solution = 0 to 1 extra point

Prizes

The pool of $20,000 TON will be split equally between the top 100 participants of the leaderboard after plagiarising participants are removed. Every participant on the leaderboard will receive a participation soulbound token (SBT).

Prize pool distribution:

  • $7,000 in TON — The top 15% of eligible participants
  • $7,000 in TON — The middle 30% of eligible participants
  • $6,000 in TON — The bottom 55% of eligible participants

Impressive, right? Hurry up and join!

Good luck!

Full text and comments »

  • Vote: I like it
  • +59
  • Vote: I do not like it

By awoo, history, 4 months ago, translation, In English

Hello, Codeforces!

On Dec/19/2023 17:35 (Moscow time) the Codeforces Round 916 (Div. 3) will start. 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, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks.

You will be given 2 hours and 15 minutes to solve 6-8 problems. The penalty for a wrong submission is equal to 10 minutes.

We remind you that only the trusted participants of the third division will be included in the official standings table. As it is written on the blog which you can access by this 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),
  • 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 were invented and prepared by Adilbek adedalic Dalabaev, Ivan BledDest Androsov, Maksim Neon Mescheryakov, Roman Roms Glazov, Alexander fcspartakm Frolov, and me. Also, big thanks to Vladislav Vladosiya Vlasov for his excellent coordination.

Thanks to Mike MikeMirzayanov Mirzayanov for Codeforces and Polygon systems!

And, the last but not the least, big thanks to the testers FBI, Kalashnikov and SonOfHonor for their valuable advice and suggestions!

Good luck in the contest! I hope you'll enjoy solving the problems we have prepared.

UPD: Editorial is out

Full text and comments »

  • Vote: I like it
  • +113
  • Vote: I do not like it

By BledDest, history, 4 months ago, In English

Hello Codeforces!

On Dec/18/2023 17:35 (Moscow time) Educational Codeforces Round 160 (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, Roman Roms Glazov, Artem Ferume Ilikaev, Ruslan AcidWrongGod Kapralov and me. Also, huge thanks to Mike MikeMirzayanov Mirzayanov for great systems Polygon and Codeforces.

The problemset partially intersects with the Open KFU Olympiad, so if you participated in it, please avoid taking part in the round.

Good luck to all the participants!

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

Harbour.Space
WORK & STUDY OPPORTUNITY IN BARCELONA @ HARBOUR.SPACE UNIVERSITY

Harbour.Space University has partnered with Giga (Unicef) to offer 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 – describing findings to a technical and non-technical audience is essential
  • 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:

  • 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
  • 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 incredibily important to describe findings to a technical and non-technical audience
  • Strong software engineering background
  • Hands-on experience with data science tools
  • Problem-solving aptitutde
  • Analytical mind and great business sense
  • Degree in computer science, engineering or relevant field is preferred

All successful applicants will be eligible for a 100% tuition fee scholarship (29,900 €/year) provided by the partner company.

CANDIDATE’S COMMITMENT

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.

REQUIREMENTS:

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

UPD: The editorial can be found here.

Full text and comments »

  • Vote: I like it
  • +53
  • Vote: I do not like it