Hello! Codeforces Round 762 (Div. 3) will start at Dec/20/2021 17:35 (Moscow time). You will be offered 7-8 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 ACM-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 7-8 problems and 2 hours and 15 minutes 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 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 teams: MikeMirzayanov, MisterGu, myav, Gol_D, Aris, senjougaharin, me Vladosiya and SGU student Brovko.

Also many thanks to Geothermal, Rafbill, Sugar_fan, mango_lassi, hitonanode, Resende, Igorjan94, CtrlAlt, KerakTelor, FlakeLCR, MatheusMonteiro, Loolo, kocko for testing the contest and valuable feedback.

Good luck!

UPD 1: The opinion of the testers about the order of problems turned out to be so heterogeneous that there is no way to be sure about the increase in the complexity of problems in the set. We advise you to read all problems.

UPD 2: If you are a schoolchild from the Saratov region, then please refrain from participating in the round. One of the problems may be familiar to you. Thanks!

UPD 3: Editorial

Hello Codeforces!

On Dec/18/2021 18:35 (Moscow time) Educational Codeforces Round 119 (Rated for Div. 2) will start. Please, note the unusual start time.

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, Roman Roms Glazov 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:

Hello once again, Codeforces!

Almost 5 months have passed since we organized the Harbour.Space Scholarship Contest 2021-2022. It’s been quite a tough challenge with more than 15,000 participants. However, we were able to select the ones who were ready to take the opportunity and join Harbour.Space this year. In addition to the contest, we carefully reviewed all scholarship applications and awarded a total of 11 students.

We would like to introduce you our Competitive Programming Scholarship Winners who have already arrived to Barcelona:

aniervs, MaksymOboznyi, 244mhq, Meijer, bthero,amanbol, DimmyT, 998kover

We are looking forward to achieving incredible results with our new ICPC teams. One of them, Harbour.Backspace (MaksymOboznyi, 244mhq, 998kover), has already finished in 3rd place during Moscow Workshops. We wish them the best in the upcoming contests.

As usual, we are always excited to see Codeforces participants as our students here at Harbour.Space

UPD: Editorial is out

Hello, Codeforces!

I am happy to invite you to Codeforces Round 761 (Div. 2), which will take place on 16.12.2021 16:35 (Московское время). The round will be rated for participants with rating lower than 2100. Notice the unusual starting time.

All the problems were authored and prepared by me. The round wouldn’t be possible without these people:

• Artyom123 for excellent coordination and translation of statements.
• KAN for help with round preparation.
• arvindf232, physics0523, SecondThread, Igorbunov, kevinxiehk, generic_placeholder_name, Kotehok3, minhcool, anthony123, Elison, shishyando, SlavicG, Absyarka, erniepsycholone, dbsbs, lomienyeet for testing and valuable feedback.
• Again, arvindf232 and generic_placeholder_name for providing solutions to a problem that are better than the author’s solution.
• Again, kevinxiehk for submitting many different solutions to a problem.
• MikeMirzayanov for great Codeforces and Polygon platforms.
• You, for participating!

You will have 2 hours to solve 5 problems, one of which is divided into two subtasks. One of the problems is interactive, please see the guide of interactive problems if you are not familiar with it.

Wish you good luck and high ratings!

Here is the score distribution: $$$750-1000-1500-(2000-1000)-3000$$$.

The editorial is here: click.

UPD: Sorry but there is a checker bug in problem E. All submissions of problem E will be rejudged soon.

UPD2: Rejudge done, the round remains rated.

Congratulations to the winners (will be updated after system tests):

We invite ML students and specialists from all over the world to take part in the International Data Analysis Olympiad. HSE University and Yandex are organizing it for the 5th time, and the Otkritie bank will be our platinum partner this year.

Since it’s our first anniversary, we decided to change the format: students and ML specialists are divided into two separate divisions. Only students are able to join the main competition — the Student Division. All others can join the Open Division to participate hors concours (for their own interest).

Traditionally, the first stage’s task will be given by the Laboratory of Methods for Big Data Analysis (LAMBDA, HSE University). It will be about predicting the properties of two-dimensional crystals of various configurations. The task for the Finals will be provided by the Otkritie bank. The Olympiad includes two stages:

Online Stage (1-28 February 2022):

• Track 1: Traditional machine learning competition on Yandex.Contest platform. You will need to make new predictions and upload them to the automatic verification system.

• Track 2: Come up with a solution for the same problem, keeping within a rigid framework of time and memory used.

Final (16-17 April 2022, Moscow):

• top 30 teams according to the Online Stage results will be invited to the Online final.

• In the final 36 hours of the competition, participants will try not just to train the model, but to create a full-fledged prototype, which will be tested both in terms of accuracy and performance.

Registration is open till February 13: https://idao.world/

Hello, Codeforces!

On Dec/14/2021 17:35 (Moscow time) the Codeforces Round 760 (Div. 3) will start. This is a usual round for the participants from the third division. The round will contain 8 problems, which are mostly suited for participants with rating below 1600 (or we hope so). Although, as usual, participants with rating of 1600 and greater can register for the round unofficially.

The round will be hosted by rules of educational rounds (extended ACM-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 (we hope that our tests are strong enough, so there won't be too many solutions hacked during this phase).

You will have to solve 8 problems in 2 hours and 15 minutes. 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 two 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 prepared by Brovko, shnirelman, Lankin, awoo and me. We would like to thank the testers of the round: vovuh, Nil_Sinyaev, IsaacMoris, altynai, MarcosK, osylai, ZulaMostafa, nondeterministic, mumumucoder, peroon and kocko.

And, the last but not the least, thanks to Mike MikeMirzayanov Mirzayanov for Codeforces and Polygon systems!

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

UPD: The editorial is out.

Hi all!

This weekend, at Dec/12/2021 18:15 (Moscow time) we will hold Codeforces Round 759 (Div. 2, based on Technocup 2022 Elimination Round 3). They are based on problems of Technocup 2022 Elimination Round 3 that will be held at the same time.

Technocup is a major olympiad for Russian-speaking high-school students, so if you fall into this category, please register at Technocup website and take part in the Elimination Round.

The Div.2 edition is open and rated. Register and enjoy the contests!

• The round authors are: Denisson, antonis.white, dimatimoshin23, napstablook, kirill.grachoff
• Thanks Makcum888, snowysecret, stevancv, wxhtzdy, and ijxjdjd for testing.

Have fun!

UPD: congratulations to the winners!

Technocup 2022 - Elimination Round 3

1. LeoPro
2. princebelkovetz
3. DDima
4. pelmenner
5. abdula-mon-fon-alibaba-A

Codeforces Round 759 (Div. 2, based on Technocup 2022 Elimination Round 3)

1. Maria_Akizuki
2. maxlevel_spyofgame
3. zhaojianmin
4. FlameDragon
5. Shawn

The editorial is published.

Hello, Codeforces community!

I'm glad to invite you to Codeforces Round #758 (Div.1 + Div. 2), which will be held on Dec/11/2021 13:05 (Moscow time). The round will be rated for both divisions. Note the unusual start time.

The problems were taken (mostly) from the ByteDance — Moscow Workshops Online Contest, which is happening at the same time. Tasks from the Online Contest are prepared by TadijaSebez and oversolver, additional tasks brought to you by Um_nik and gen. We are very thankful to the testers: Monogon, 74TrAkToR, AmShZ, DeadlyCritic, errorgorn, oolimry and icypiggy for their time and great feedback. Also big thanks to authors of other problems of the Online Contest snarknews and teraqqq for cooperation, Bytedance instructors jqdai0815, Syloviaely, Gromah, Claris for testing and reviewing the Bytedance online contest, the contest coordinator antontrygubO_o for the great help in setting up that round and MikeMirzayanov for testlib.h, Polygon and Codeforces.

ByteDance is a global technology company operating a range of platforms that allow people across languages, cultures, and geographies to create, discover and connect. ByteDance has partnered with Moscow Workshops and Codeforces to organize a top-tier and exclusive training camp for the International Collegiate Programming Contest. The upcoming Programming Camp will be held in Beijing from February 17th to 23th, 2022.

ByteDance — Moscow Workshops Online Contest is an opportunity to participate as teams onsite in this camp. Due to COVID-19 restrictions, mainly teams from China can participate onsite this year. For the international teams, the opportunity of online participation is considered.

You can find more information about this training camp at https://programcamp.bytedance.com/.

UPD: The scoring distribution is 250 — 750 — 1000 — 1500 — 2000 — 2500 — 2750.

UPD 2: Editorial

Hi, Codeforces users!

We are announcing ITMO Winter Camp in Competitive Programming that will be held online. On each of the 10 days from January 10 to 21 (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:

• Algorithms, Complexity, O-notation, Recursion
• Sorting and Binary Search
• Dynamic Programming
• Graphs, DFS, SCC finding
• Graphs, Shortest paths, BFS, Dijkstra's algorithm
• Strings, Prefix-function, Z-function
• Segment Tree

The main topics will be covered for sure, but other topics on the official website can be changed depending on average level of students. If you already attended our camps before, be careful, this one will contain the same topics.

Our tutors: VArtem, niyaznigmatul, Aksenov239, GShark, budalnik.

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

To apply, visit https://schools.itmo.ru/en/school/26/. Application deadline is December, 15, 2021.

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

We are aiming that there will probably be two learning groups, at different times of day, for students from different timezones. The current plan is: Morning classes are held from 11:00 to 15:00, evening classes – from 17:00 to 21:00 (GMT +3).

Hello Codeforces!

On Dec/01/2021 17:35 (Moscow time) Educational Codeforces Round 118 (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, Roman Roms Glazov 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