Hi.

Of course, there was an unpleasant incident with the problem today. In fact, the problem almost coincided with another problem in the old round, which was hosted 5 years ago.

You, of course, are shocked. You, of course, think that the round should be unrated.

You are wrong. Here's why.

Hi everybody,

This Sunday there will be a Moscow Olympiad for Young Students. This contest is prepared by Moscow Olympiad Scientific Committee that you may know by Moscow Open Olympiad, Moscow Team Olympiad and Metropolises Olympiad (rounds 327, 342, 345, 376, 401, 433, 441, 466, 469, 507, 516, 541, 545, 567, 583, 594, 622, 626, 657, 680, 704, 707, 727, 751, 775, 802, 829).

The round will be held at Feb/12/2023 11:35 (Moscow time) and will last for 2 hours. Note the unusual time of the round. The round will be held according to the Codeforces rules and will be rated.

Problems of this competition were prepared by Tikhon228, TheEvilBird, Ormlis, vaaven, Gornak40, Honey_Badger guided by vaaven, grphil and Helen Andreeva.

Thanks to Artyom123 for the round coordination, and also thanks for MikeMirzayanov for systems Codeforces and Polygon, which was used to prepare problems of this olympiad.

Thanks to BucketPotato, KseniaShk, NemanjaSo2005, MagentaCobra, kuertov, prvocislo, 4qqqq, vsinitsynav, FynjyBath, qualdoom, ivanlarin, didedoshka, petyb, PBBx0, Mikhango, charlyk, RP-1, talant, ak2006 for testing.

Due to the official competition source codes of other participants will not be available for an hour after the end of the round.

Good luck everybody!

UPD: Score distribution: 500 — 1000 — 1250 — 1750 — 2500 — 3250

UPD2: Еditorial

Hello Codeforces and welcome back to another div2 round.

YeongTree and I are excited to invite everyone to participate in Codeforces Round 851 (Div. 2), which will be held on 09.02.2023 17:35 (Московское время).

This round is rated for the participants with ratings strictly lower than 2100. You will be given 6 problems and 2 hours to solve them. All the problems are authored and prepared by YeongTree and me.

We would like to thank

• Arpa for excellent coordination and help with prepration.
• Alexdat2000 for Russian translation.
• blobugh, as_dfsdf, Kawaii2DIdolOfGSHS, nlog, Ryute, Konijntje, hanbyeol_, Physics07, jjang36524, OctaneC8H18, ahgus89, DELTARUNE, FD..LH..lloyJ, andyandy, PUFL, Pratyush1606, PUPA, Justice_Hui, garam1732, windva, culver0412, nor, maomao90, MagentaCobra, dorijanlendvaj, RetiredPlayer, mejiamejia, AquaMoon, mjhmjh1104, qwexd, ayhan23 for testing and feedbacks.
• MikeMirzayanov for great systems Codeforces and Polygon.

The score distributions will be updated later.

UPD1: Score distribution: $$$500−1000-1500-2250−2500-3000$$$

UPD2: Congratulations to the winners!

Overall:

1. jiangly
2. MakaPakka
3. MahiruShiina
4. maspy
5. tute7627

Rated participants

1. MakaPakka
2. _10circle_
3. JJcjn
4. 1cm
5. YouPervertSucker

AC submissions at the last second

• gsmdfaheem
• YoussefMorad1
• darshil_31

UPD3: Editorial is out

Hello!

Welcome to Codeforces Round 850 (Div. 1, based on VK Cup 2022 - Final Round) and Codeforces Round 850 (Div. 2, based on VK Cup 2022 - Final Round) that will start on Feb/05/2023 15:05 (Moscow time). Both rounds will be rated.

This round is a mirror of VK Cup 2022 Final — 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 of Div. 1 round are authored and prepared by me, while KAN authored and prepared two problems for Div. 2. Thanks to errorgorn, irkstepanov, qwerty787788, Merkurev, IgorI, PavelKunyavskiy, izban, Alexdat2000, ashmelev, Akulyat, mike_live, Ekler, Kalashnikov for making this round better.

You will be given 6 problems and 3 hours to solve them.

UPD: Editorial

Congratulations to the winners:

1. ksun48
2. maroonrk
3. QuietBeautifulThoughts
4. Mr_Eight
5. ecnerwala

Hello Codeforces!

flamestorm, SlavicG, MikeMirzayanov and I want to invite you to Codeforces Round 849 (Div. 4).

It starts on Feb/03/2023 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 behaviour. 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.

Many thanks to the testers: _Vanilla_, badlad, Gheal, Phantom_Performer, Beacon, Nihad_Nabelsi, prvocislo, keta_tsimakuridze, Bakry, RedstoneGamer22, tibinyte, KrowSavcik, haochenkang, myvaluska, sandry24, BucketPotato, Vladosiya, pashka.

We suggest reading all of the problems and hope you will find them interesting!

Good Luck!

UPD: Editorial is posted.

Hello, Codeforces!

adnan_toky and I are super thrilled to invite everyone to participate in Codeforces Round 848 (Div. 2), which will be held on Feb/01/2023 17:35 (Moscow time).

This round is rated for the participants with ratings strictly lower than 2100. You will be given 6 problems and 2 hours to solve them. All the problems are authored and prepared by adnan_toky and me. To get the 6 problems approved, we needed to propose 12 problems in total .

UPD: Score distribution: $$$500-1000-1250-1750-2250-2750$$$

We would like to thank:

• darkkcyan for incredible coordination and help with the problem preparation
• Alexdat2000 for the Russian translations and precious help regarding the statements and limits
• KAN for upgrading the quality of statements
• Gary2005, awoo, Huah, feecle6418, vinfat, marvinthang, Psychotic_D, tolbi, Black_Be4rD, Hasnaine_, tanus_era, thisIsMorningstar, __FaRiA_eFa__, masood_, Ryu204, badlad, TomiokapEace and ayhan23 for testing this round and providing valuable feedbacks
• MikeMirzayanov for the amazing Codeforces and Polygon platforms
• You, for participating in this round

This is our first round! We've tried our best to make the round enjoyable. It is greatly recommended to read all the problems.

We are looking forward to your participation. Good luck to everyone .

UPD2: Congratulations to the winners!

Overall:
1. jiangly
2. SSRS_
3. Geothermal
4. BurnedChicken
5. Ormlis

Div. 2:
1. CoCl2_6H2O
2. Joyemang
3. gqh_cpp
4. rainboy
5. NoMentalPowerLeft

UPD3: Editorial is out

Greetings, CodeForces!

jiangtaizhe001, qzhwlzy and I rsj are more than excited to invite you to participate in TypeDB Forces 2023 (Div. 1 + Div. 2, Rated, Prizes!), which starts on Jan/29/2023 17:35 (Moscow time).

The round is open and rated for everyone. You are given 9 problems, no subtasks or interactive problems, and you have 3 hours to solve them. It is recommended to read all problems. The statements were made as briefly and clearly as we could. Enjoy the contest!

UPD: Score distribution: $$$500-1000-1750-2000-2250-2500-3250-3500-3750$$$

Sincere thanks to:

• 74TrAkToR, for a long-term, tough and perfect coordination.
• qzhwlzy, for writing and polishing statements and tutorials, and sparky ideas.
• jiangtaizhe001, for helping me a lot in preparation.
• 275307894a and A_zjzj, for providing wonderful problems and solutions.
• carnation13, willy108, NemanjaSo2005 and EverlastingEternity for great suggestions to the problems.
• NemanjaSo2005, EverlastingEternity, plagues, WGYHMFkZyA02, xiongyushun, dorijanlendvaj, AlexLuchianov, Gary2005, SSerxhs, RUSH_D_CAT, Lavine, Kieray, Alice114514, Atziluth, Depth_First_Search, OdtreePrincess, A_zjzj, _WD_, 275307894a, Electric_Field, carnation13, Hanriver, some_idiot, willy108, gamegame, Pointy, Huah, ShmilyTY, njupt_lyy, E_huan, p_b_p_b, jjjjssss6, HolyK, -skyline- and Isla81920, for testing the contest and providing useful feedback.
• MikeMirzayanov, for the great systems Codeforces and Polygon.

Thanks to Vaticle's sponsership, winners will receive awesome prizes!

Cash and Swag Prizes

• 1st place: 500 Euros
• 2nd place: 250 Euros
• 3rd place: 100 Euros
• Top 50: TypeDB hoodie, t-shirt and stickers
• Random 50 of 51-250: TypeDB t-shirt and stickers

About Vaticle & TypeDB

Vaticle is a team of people driven to empower engineers to solve complex problems. We are the creators of the strongly-typed database, TypeDB, and its query language, TypeQL. You can find out more about our work from another announcement post, interview post, our website and GitHub pages. You can also apply directly to our team using the button below:

UPD1: Editorial

UPD2: Congratulations to the winners:

• ko_osaga
• tourist
• Radewoosh
• Benq
• ecnerwala

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, senjougaharin and Vladosiya. Also this time, molney suggested one of the tasks.

We would like to thank: alwyn, morasha3, csegura, BledDest, stevenkplus, Darko, Coki628, Crutch, Qwerty1232, Jostic11, liouzhou_101, Jeffin, AW_Flister, glebustim, yorky, mango_lassi, 74TrAkToR, ErrorDeveloper, Be_dos, MODDI, Vercingetorix for testing the contest and valuable feedback. List of testers will be updated.

Good luck!

UPD: Editorial

Hello, Codeforces!

IzhtskiyTimofey, 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.

• blobugh, 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.