Hello! Codeforces Round #847 (Div. 3) will start at Jan/27/2023 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 6-8 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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of our work. Problems have been created and written by ITMO University team: MikeMirzayanov, myav, Gol_D, Aris, Gornak40, DmitriyOwlet and Vladosiya. Also this time, molney suggested one of the tasks.

We would like to thank: Crutch, Coki628, stevenkplus, Be_dos, MODDI, Darko, Jostic11, yorky, 74TrAkToR, glebustim, AW_Flister, morasha3, csegura, Jeffin, Vercingetorix, BledDest, liouzhou_101, for testing the contest and valuable feedback. List of testers will be updated.

Good luck!

Hello, Codeforces!

T4M0FEY, qualdoom and I are glad to invite everyone to participate in Codeforces Round #846 (Div. 2), which will take place in Jan/25/2023 17:35 (Moscow time).

This round will be rated for the participants with rating lower than 0x834 (i.e. 2100). Participants with a higher rating can take part in the round unofficially.

You will have 7 tasks and 2 hours to solve them.

One of the problems will be interactive. Make sure to read this blog and familiarize yourself with these types of problems before the round!

I want to sincerely thank everyone who provided invaluable help in preparing the round and made it many times better:

• 74TrAkToR for rejection of 10+ tasks an idea for a problem, help in preparing the round and excellent coordination!

• KAN for upgrading the quality of statements.

• tlsdydaud1, maomao90, maks_matiupatenko, loggerr, vdv09, alex.kudryashov, FynjyBath, alexey.shchepin, Alcabel, induk_v_tsiane, Siberian, polosatic, FedShat and tryharder for testing the round and useful feedback!

• MikeMirzayanov for Codeforces and Polygon platforms!

• You for participating in this round.

This is our first official round on Codeforces. We sincerely hope to your participation. We hope that you will like the proposed tasks!

The score will be announced closer to the start of the round.

We wish you good luck and have a good time! See you in the round!

UPD: Scoring distribution: $$$500-1000-1250-1500-1750-2000-2500$$$

UPD: Round is unrated. We're sorry — it's our fault.

UPD: Tutorial and comment about task C Once again, we apologize for the inconvenience caused.

Hello, everyone!

We look forward to our upcoming competition — TypeDB Forces 2023 (Div. 1 + Div. 2, Rated, Prizes!), which will take place on Jan/29/2023 17:35 (Moscow time). In the meantime, you can learn a little more about us.

We’re from Vaticle, and we’re the creators of TypeDB & TypeQL. All members of our team are unique and talented, and today we want to introduce you to one of them.

How would you introduce yourself?

I'm Krishnan, I grew up in India and spent a little too much time on the internet and fiddling with my (underpowered) PC. After completing my Bachelor's degree, I spent a year as a software engineer working on a huge data lake, the next as a research fellow trying to permute thread executions to force out concurrency bugs, a year doing a masters with a focus on the old-style AI (and logic-programming). After a short-lived attempt at a Ph.D., I'm now at Vaticle working on the automated reasoning built into our database.

When did you start Competitive Programming?

Probably in my second year of uni. One of my friends decided it would be fun and we just started doing contests. Later on, another friend convinced me to learn a bit more and join his ICPC team. The discussions I had with him were great.

What have you since learned and how has competitive programming impacted your skills?

Everyone reading this knows better than me, but CP has made me a lot better at dissecting a problem better and isolating the crux of it. It also makes you great at coming up with the simplest possible implementation which covers all the (edge) cases. The clarity of thought you need to get an AC is something I would have taken much longer to develop without it.

What is it like working at TypeDB as an Engineer?

The problems you get to work on here at Vaticle are great fun. There's a nice balance of freedom to explore solutions and expectations on output- so you're happy with the state of whatever you're building. It feels like a good time to be at the company because we're stable enough to know what we want to do and have some idea of how we want to do it, but still early enough that you have to define and drive the solution.

Another great thing is the variety of fields we touch on in our work — There's something in it for almost everyone. The query language and type system design, the semantics of the language, the graph traversal algorithm, the storage engine, and its low-level data structures, and the distributed systems aspect to scale it all up. We even have our own IDE (and a very, very cool graph visualizer). You also have to dive into the internals of programming languages, build systems, and cloud infrastructure.

To top it all off, with the group of extremely smart people working here and their varied interests, you have a lot of great (and often tangential) discussions in the meeting room, the lunch table (and the pub). Even so, I think we could do with a few more competitive programmers in the team ;)

What kind of problems are you working on?

The focus of my work is the reasoner (which sits well with my interest in logic programming). The first major piece of work here was the resolution planner – what is the best order to evaluate a recursive query? The discussions with my colleagues were critical to making heads or tails of the problem. It could still use some work though (anyone like decomposing graphs?)

I've since worked on adding arithmetic & aggregate queries into the system — which involved finding the right conceptual model to think about all these in a graph setting. We've had some great discussions on the various database models and how it fits into their systems.

The next chunk of work I look forward to is to tame the reasoner a little more. The current solution is very elegant — it's simple and powerful as a direct result of its simplicity. We just need to add a few missing properties to the resolution procedure to bring it up to the state of the rest of the system.

The data in knowledge graphs tend to be highly interconnected, and we know interconnectedness is a recipe for hard problems.

So, if you already want to become a member of our team, then without delay fill out this form. But, if you need more details about us and our work, we invite you to our website and GitHub pages.

Hello Codeforces!

On Jan/24/2023 17:35 (Moscow time) Educational Codeforces Round 142 (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, 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:

Hey, Codeforces!

Preparations are under way for the second “Hello Muscat 2023” ICPC programming bootcamp, the continuation of the “Hello” bootcamp series, organised by Harbour.Space University, in collaboration with PhazeRo, Gutech, UK Oman Digital Club, Leagues of Code, Gutech CS Club and Codeforces!

Quite exciting, isn’t it? Now it's time for you to dive deeper into the competitive programming world with the 8 days intensive Hello Muscat 2023. It will take place in Muscat, Oman and online from March 8th to March 16th, 2023, both participation formats are available. As always, we can’t wait to see you there to learn, practice and compete on the international stage, smoothing your road towards the joined World Finals 2022 and 2023 in Egypt!

Our coaching line-up combines talent and experience, featuring ICPC world champions winners and finalists, as well as legendary names from the field of competitive programming: Mike Mirzayanov MikeMirzayanov, Yahor Dubovik 244mhq, Artem Plotkin Rox, Maksym Oboznyi MaksymOboznyi and Nikolay Budin budalnik.

The Bootcamp will be split into three divisions:

• Division A. Division A will be a mirror of the Petrozavodsk Programming Camp. Suitable for teams who already qualified for the world finals ICPC or are aiming that high.
• Division B. Designed to help teams prepare for the next season of ICPC regional competitions. Appropriate as an introduction for teams and students just getting their foot in the door of the world of ICPC and competitive programming competitions in general.
• Division C. Designed for newcomers to the world of ICPC competitive programming.

Types of participation: On-Site and Online

_We believe that participation in our Bootcamp should be accessible by all teams wherever they are and that is why we made onsite and online types of participation. 20% Early Bird Discount is offered to universities and participants who register and pay before Jan 31st 2023.

• On-site:

Price: 1500 € — 1200 €

What is included: training, contests, access to the recordings of the lectures, accommodation for 9 nights in a 4 star hotel Mysk, breakfast and lunch, transfer from hotel to venue every day, leisure, entertainment and welcome pack.

• Online:

Price: 100 € — 80 €

What is included: training, contests, access to the recordings of the lectures.

Good luck with the round!

UPD: Editorial is out

Hello, Codeforces!

NJACK — the Computer Science Club of IIT Patna is excited to invite you to ByteRace 2023 — Codeforces Round #845 (Div. 2) and ByteRace 2023 under Celesta — the annual Techno-Management Fest of IIT Patna.

The contest will take place on Jan/21/2023 17:35 (Moscow time). This round will be rated for participants with rating lower than 2100.

Many thanks to all the people who made this round possible:

• The problems were authored and prepared by me, quantau, mayankfrost, ShivanshJ, Crocuta and AwakeAnay.
• irkstepanov and KAN for coordinating the round!
• jenishmonpara, 100gods and V_S_M for their guidance throughout the process.
• VIP testers: YashPant and Newtech66 <3
• Shoutout to AwakeAnay for doing absolutely nothing.
• dorijanlendvaj, Golovanov399, nor, defnotmee and ilya151098 for testing and providing detailed feedback that improved the quality and balance of the round significantly.
• Our lord and saviour MikeMirzayanov for great systems Codeforces and Polygon.

You will have 2 hours to solve 6 problems.

The scoring distribution will be updated later.

UPD: Scoring distribution: $$$500-1000-1500-2000-2250-2750$$$

UPD: Editorial

UPD: Congratulations to the winners!

Official winners:

1. jiangly_fan_fan_fan_fan
2. ducati
3. xiachong
4. FasterThanLight
5. Remask_588_handles

Unofficial winners:

1. noimi
2. jiangly_fan_fan_fan_fan
3. Nyaan
4. ducati
5. neal

First solves:

A: noimi at 00:00
B: neal at 00:02
C: noimi at 00:06
D: noimi at 00:09
E: noimi at 00:15
F: sjc061031 at 00:13

PRIZES: 30 hoodies (customizable with name) will be given to:

• Top 20 Indian participants
• Random 10 from top 100 (rank 21-100) Indian participants

Note: we will identify Indian participants through their flags and they may be asked for address proofs later.

See you all in the standings!

About Celesta

Celesta is the annual Techno-Management Fest of IIT Patna. Celesta conducts a variety of events in various technical domains. Some of these are open and free for all, with exciting prizes and goodies for the winners!

You can head over to our website and check it out for yourself!

Good luck!

Hello!

Welcome to the Codeforces Round #844 (Div. 1 + Div. 2, based on VK Cup 2022 - Elimination Round) that will start on Jan/15/2023 15:05 (Moscow time). It will be a combined rated round for both divisions and open to everyone.

This round is a mirror of VK Cup 2022 Elimination — annual programming championship for Russian-speaking competitors organized by VK. VK Cup started in 2012 and has grown to be a five-track competition in competitive programming, Mobile, ML, Go, and JavaScript.

All the problems are authored and prepared by me. Thanks to KAN, errorgorn, lperovskaya, dario2994, Monogon, Arpa for making this round better.

You will be given 8 problems and 3 hours to solve them.

UPD: Editorial

Congratulations to the winners:

1. orzdevinwang
2. noimi
3. Radewoosh
4. gamegame
5. QAQAutoMaton

and to maroonrk for getting the only accepted solution to problem H2.

Hello, Codeforces!

I am very glad to invite you to the Codeforces Round #843 (Div. 2), which will take place in Jan/10/2023 14:15 (Moscow time). This round will be rated for the participants with rating lower than 2100.

My sincere thanks to:

• KAN и Aleks5d for the great coordination of this round!

• Wind_Eagle, BaluconisTima, kartel и Aleks5d for the tasks ideas, and also Wind_Eagle, BaluconisTima, kartel, VEGAnn и Vladik for preparing the tasks.

• andrew, gepardo, 244mhq, vilcheuski the rest of the author team, without whom this round would not have happened.

• BaluconisTima for the splendacious pictures, which complement each problem.

• MikeMirzayanov for Codeforces and Polygon platforms.

• You for participating in this round.

You will have 2 hours and 30 minutes for solving 6 tasks, one of which will be divided into easy and hard verions. The round is based on the problems from the first day of Belarusian Regional olympiad. We kindly ask all Belarusian pupils who participated in this olympiad, to refrain from taking part in this round and discussing the problems publicly before the round ends.

I hope you will enjoy the round!

Round testers (not complete list): MathBoy, FairyWinx, nnv-nick, K1ppy, olya.masaeva, Septimelon, PavelKorchagin, 4qqqq, kova1.

Score distribution: (500+1000)-1000-1500-2000-2000-2500.

UPD. Score distribution was changed: (500+500)-1000-1500-2000-2250-3000.

UPD2: Congratulations to the winners!

Vote for your favourite task!

Task А: Gardener and the Capybaras

Task B: Gardener and the Array

Task C: Interesting Sequence

Task D: Friendly Spiders

Task E: The Human Equation

Task F: Laboratory on Pluto

UPD3: Finally, here is the editorial: press here

Hello Codeforces!

On Jan/08/2023 17:35 (Moscow time) Educational Codeforces Round 141 (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, 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:

Hey, Codeforces!

We are pleased to announce the second “Hello Muscat 2023” ICPC programming bootcamp, the continuation of the “Hello” bootcamp series, organised by Harbour.Space University, in collaboration with PhazeRo, Gutech, UK Oman Digital Club, Leagues of Code, Gutech CS Club and Codeforces!

Quite exciting, isn’t it? Now it's time for you to dive deeper into the competitive programming world with the 8 days intensive Hello Muscat 2023. It will take place in Muscat, Oman and online from March 8th to March 16th, 2023, both participation formats are available. As always, we can’t wait to see you there to learn, practice and compete on the international stage, smoothing your road towards the joined World Finals 2022 and 2023 in Egypt!

Our coaching line-up combines talent and experience, featuring ICPC world champions winners and finalists, as well as legendary names from the field of competitive programming: Mike Mirzayanov MikeMirzayanov, Yahor Dubovik 244mhq, Artem Plotkin Rox, Maksym Oboznyi MaksymOboznyi and Nikolay Budin budalnik.

The Bootcamp will be split into three divisions:

• Division A. Division A will be a mirror of the Petrozavodsk Programming Camp. Suitable for teams who already qualified for the world finals ICPC or are aiming that high.
• Division B. Designed to help teams prepare for the next season of ICPC regional competitions. Appropriate as an introduction for teams and students just getting their foot in the door of the world of ICPC and competitive programming competitions in general.
• Division C. Designed for newcomers to the world of ICPC competitive programming.

Types of participation: On-Site and Online

We believe that participation in our Bootcamp should be accessible by all teams wherever they are and that is why we made onsite and online types of participation. 20% Early Bird Discount is offered to universities and participants who register and pay before Jan 31st 2023.

• On-site:

Price: 1500 € — 1200 €

What is included: training, contests, access to the recordings of the lectures, accommodation for 9 nights in a 4 star hotel Mysk, breakfast and lunch, transfer from hotel to venue every day, leisure, entertainment and welcome pack.

• Online:

Price: 100 € — 80 €

What is included: training, contests, access to the recordings of the lectures.

Good luck with the round!

UPD: Editorial is out