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, Nebuchadnezzar.

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

Hi, Codeforces!

We are DELTIX. Founded in 2005, DELTIX is one of the market leaders in software development for financial research and products for systematic and algorithmic trading. In 2020 DELTIX joined the EPAM family. Our mission is to turn promising ideas into breakthrough products fast.

We are experts in:

• aggregation, storage, and processing large volumes of time-series data
• data modeling
• testing and deployment of quantitative models

In our team we value such skills as:

• knowledge of algorithms
• high-performance coding
• low latency data streams processing

We are excited to announce that we have released TimeBase Web Admin Community Edition.

More about DELTIX

Throughout the year, once per quarter, we will be inviting you to join DELTIX rounds at Codeforces. Today, we are excited to welcome you to the third installment of our rounds (joined Div1 и Div2) Deltix Round, Autumn 2021 (open for everyone, rated, Div. 1 + Div. 2), that will start on Nov/28/2021 17:35 (Moscow time). It is an open and rated round for both divisions.

We have prepared the following trophies for you:

1st place: Samsung Galaxy Z Flip3
2nd place: Samsung Galaxy Tab S7+
3rd place: Samsung Galaxy Watch4
1-100 places: branded t-shirts

Another 100 t-shirts will be distributed randomly between participants outside the top-100 but within the top-1000 and who participated in rated Codeforces rounds before.

Problems, except the last one, have been prepared by members of our team: Vladik, 4llower and AleXman111.

We would like to say a word of appreciation to:

• KAN and Nebuchadnezzar for the round management
• extra thanks to Nebuchadnezzar for creating one of the problems
• all the testers: Heltion, kefaa2, Geothermal, andrew, aSmallTyphoon, _Time_Lord_, Hec, GusMG, shxgun, 221, BOT_SaNyA, senyaa, avoronoi, fixikmila, JAMMY, Whiplash99, Ghazoo, Jon, bu6lik, Zayadi, M.Bot, Omar_Elaraby, Kart, Java and anegelytor.
• and also MikeMirzayanov for Codeforces and Polygon systems

We will offer participants 8 problems and 150 minutes to solve them. We wish everybody good luck and high ratings!

Fill out a short contact form if you are interested in employment opportunities or would like to speak with recruiters or members of our team.

UPD: The scoring distribution is 500 — 1000 — 1500 — 2000 — 2750 — 3000 — 3250 — 3750.

Thank you all for participating! (editorial)

Congratulations to the winners:
1. tourist
2. DmitryGrigorev
3. xtqqwq
4. Maksim1744
5. peehs_moorhsum
6. maroonrk
7. jiangly
8. Miracle03
9. QAQAutoMaton
10. emptyhope

We were especially delighted with the result tourist, who was able to solve all 8 problems, congratulations!

Hello, Codeforces!

On Nov/26/2021 14:15 (Moscow time) Codeforces Round #757 (Div. 2) will start. This round will be rated for participants with a rating less than $$$2100$$$.

All the problems were authored and prepared by vaaven and me.

You will be given $$$5$$$ problems, one of which has two subtasks. You will have 2 hours to solve them.

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

• First of all, errorgorn and lollihunter for help with translating the terms into English.
• Aleks5d and KAN for excellent coordination.
• Ormlis, kostia244, errorgorn, Ziware, Makcum888, m371, fishy15, Sprdalo, Riladavin, Ekler, FairyWinx, olya.masaeva, LetterC67, vasilykuzmin22, TheEvilBird, JAMMY, Kolychestiy, QuangBuiYT, nikolayfedoroff and WinCrash91 for testing and useful feedback.
• MikeMirzayanov for great Codeforces and Polygon platforms.

Score distribution: $$$500$$$ — $$$750$$$ — $$$1500$$$ — $$$(1500 + 1000)$$$ — $$$2750$$$.

Good luck everyone!

UPD: Editorial

Hello! Codeforces Round #756 (Div. 3) will start at Nov/25/2021 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, Vladosiya, Aris_244_, dim3x38on and me Gol_D.

Also many thanks to A_Killer, Bugman, FlakeLCR, Igorjan94, Jester, KHiMAeRA, KerakTelor, Loolo, Matheus.Monteiro, Resende, cat998__, dedlocc, doreshnikov, kbats183, kocko, meow__353 and pashka for testing the contest and valuable feedback.

Good luck!

UPD: Editorial

Hello, Codeforces!

On Nov/23/2021 17:35 (Moscow time) we will host Codeforces Global Round 17.

It is the fifth round of a 2021 series of Codeforces Global Rounds. The rounds are open and rated for everybody.

The prizes for this round:

• 30 best participants get a t-shirt.
• 20 t-shirts are randomly distributed among those with ranks between 31 and 500, inclusive.

The prizes for the 6-round series in 2021:

• In each round top-100 participants get points according to the table.
• The final result for each participant is equal to the sum of points he gets in the four rounds he placed the highest.
• The best 20 participants over all series get sweatshirts and place certificates.

Thanks to XTX, which in 2021 supported the global rounds initiative!

The problems were written and prepared by AliShahali1382(Ali Shahali), AmShZ(AmirMohammad ShahRezaei), DeadlyCritic(MohammadHossein Paydar), Keshi(Alireza Keshavarz), alireza_kaviani(Alireza Kaviani).

We would like to thank these people:

• antontrygubO_o, for coordinating and helping a lot to make this round happen.
• Tet(Soroush Sahraei) and -zeus-(Alireza Samimi) for giving ideas for some problems.
• our testers for testing and providing helpful feedbacks: gamegame, Kalam, Amoo_Safar, prabowo, dorijanlendvaj, aarr, Parsa84, nor, ArshiaDadras, -zeus-, ijxjdjd, Sohsoh84, chctxdy68, m371, naman1601, mblazev, fatemetmhr, hiva_, manish.17, Saman., SMahdi, Vjovein, mohammad_rastegar.
• again gamegame for being an orz tester and ACing all of our problems!
• MikeMirzayanov for codeforces and polygon platform!

You will have 3 hours to solve 9 problems. As usual, it is highly recommended to read all problems!

The score distribution will be announced at least 5 minutes before the round starts! :)

Score distribution : 500 — 1000 — 1500 — 2250 — 2500 — 2750 — 3250 — 3500 — 4000.

Editorial is out

Hello Codeforces!

On Nov/22/2021 12:35 (Moscow time) Educational Codeforces Round 117 (Rated for Div. 2) will start.

The problems are based on the Southern Russia and Volga Cup 2021, which is a regional contest of ICPC. If you have participated in it or are planning to play it as a virtual contest, please refrain from taking part in the Educational Round.

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.

Hi all!

This weekend, at Nov/14/2021 09:05 (Moscow time) we will hold Codeforces Round #755 (Div. 1, based on Technocup 2022 Elimination Round 2) and Codeforces Round #755 (Div. 2, based on Technocup 2022 Elimination Round 2). They are based on problems of Technocup 2022 Elimination Round 2 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.

Div. 1 and Div.2 editions are open and rated for everyone. Register and enjoy the contests!

• The round authors are: Denisson, antonis.white, dimatimoshin23, __JustMe__, 4qqqq, Aleks5d
• Coordinator: isaf27
• Thanks KAN for help with round preparation, also thanks MikeMirzayanov for the great Codeforces and Polygon systems.
• Thanks 221, Makcum888, Melonade, 1-gon, manish.17, gjaiswal108, mathusalen for testing.

Have fun!

The scoring distribution:

• Technocup: 500 — 500 — 1000 — 1500 — 2000 — 2500 — 3250
• Div1: 500 — 1000 — 1500 — 2000 — 2750 — 3750
• Div2: 500 — 500 — 1000 — 1500 — 2000 — 2500

The round is over. Congratulations to the winners:

Technocup

1. Artyom123
2. turmax
3. Kirill22
4. expwmh
5. Kapt

Div1

1. ko_osaga
2. maroonrk
3. xay5421
4. jiangly
5. uwi

Div2

1. 1443356159
2. int65536
3. strongerthanspeed
4. DSair
5. nunu03

Editorial

Henlo Codeforces!

We are very glad to invite you to the Codeforces Round #754 (Div. 2), which will be held on Nov/12/2021 17:35 (Moscow time). This round will be rated for participants with a rating less than $$$2100$$$. For higher rated participants, we challenge you to solve problem F ;)

All the problems were authored and prepared by Ashishgup, the_hyp0cr1t3, ExplodingFreeze and me. We have tried our best to create an interesting problemset with clear statements. Hope you enjoy the round :D

You will be given $$$6$$$ problems and $$$2$$$ hours to solve them.

We would like to thank:

• antontrygubO_o for his amazing coordination and help in improving our problems.

• Our army of testers: Um_nik, kefaa2, 1-gon, _runtimeTerror_, Jeel_Vaishnav, AmShZ, errorgorn, ijxjdjd, Utkarsh.25dec, Dragnoid99, yash_daga, Vivek1998299, Discombobulated, hu_tao, _cherry_, sinus_070, AC_007, talibmohd, KahanHai, Dragonado, Submit_Galactic_Algo, KeyurJain, tvcv901, ekanshi, Jellyman102, jimmy18, inferno14 for testing the round and providing valuable feedback.

• MikeMirzayanov for the Codeforces and Polygon platforms.

Here's the scoring distribution of the round:

$$$500 - 1000 - 1500 - 2000 - 2500 - 3500$$$

UPD: Editorial is out

Also, congratulations to the winners.

Div 1 + 2:

1. SSRS_

2. Vercingetorix

3. YanZhuoZLY

4. codinglunch

5. hank55663

Div 2:

1. YanZhuoZLY

2. codinglunch

3. huyinghao0706

4. MongoliaTop

5. RimuruTempest