Hi Codeforces! Happy Dragon Boat Festival!

We are glad to invite you to our first Codeforces Round Codeforces Round 796 (Div. 1) and Codeforces Round 796 (Div. 2) which will be held on Jun/03/2022 17:35 (Moscow time). This round will be rated for participants of both divisions. Participants in each division will be offered 6 problems and 2 hours to solve them. The two divisions will share 3 problems.

In this round, as the best friend of the characters in Touhou Project, you are going to help them solve the problems they meet.

The problems are prepared by xiaoziyao, Yakumo_Ran, SSerxhs, Cocoly1990, LilyWhite, Elegia and me. We hope you will enjoy this round.

Great thanks to:

• RedMachine-74 for good coordination of this round and translating all statements to Russian,
• Yakumo_Ran for providing most tasks,
• SSerxhs for preparing most tasks,
• LilyWhite for polishing statements,
• Elegia, QAQAutoMaton, jqdai0815, Kevin114514, Suika_predator, loveye, Serval, ix35, Miko35, mrsrz, SanweiTreap, Eden_CY,wind_whisper,xuezhe, Cocoly1990, KaguyaH, meowcneil, plagues, marzipan, nhc, SCL_, zarubin for testing our round,
• KagamineRin, huhaoo, juju054, JohnVictor and Zcusss for other help,
• MikeMirzayanov for the amazing Codeforces and Polygon platforms.
• NEAR for supporting this round, details can be found in this post.

Please pay attention that there will be no more than 998244353 interactive problems in this round, so learn more about interactive problems here before the contest.

Good luck & Have fun!

UPD 1:

Score Distribution:

Div2: $$$500 - 750 - 1250 - 1500 - 2000 - 3000$$$

Div1: $$$500 - 750 - 1500 - 1500 - 2000 - 3000$$$

UPD 2:

Editorial is out.

UPD 3:

Winners

Div.1:

1. Um_nik
2. heuristica
3. jiangly
4. tourist
5. SSRS_

Div.2:

official:

1. Hanasaki
2. tkended
3. boboGM_when
4. a_nanas
5. rondoudou

unofficial:

1. Teating_
2. AgafonovArtem
3. luogubot
4. znqd3116
5. XiShui_AKIOI

Namaste Codeforces!

We are excited to invite everyone to CodeCraft-22 which will take place on May/31/2022 17:35 (Moscow time). It is rated for all people who are below yellow! (rating under 2100)

The Programming Club at IIIT-H organizes this event under Threads'22, as a part of our techno-cultural fest Felicity, IIIT Hyderabad.

There are 6 Problems with 2 hours to solve them. The scoring distribution will be released soon!

We have worked hard to keep the statements clean and the pretests strong! After the contest, step-wise tutorial and video tutorial will be released along with the code!

• This round was wonderfully co-ordinated by darkkcyan and KAN orz!
• This round was a joint effort by rahulgoel, menavlikar.rutvij, ltc.groverkss, akcube, fangahawk, JadeReaper, keyurchd_11 and me!
• KAN also translated the statements to Russian! благодарю вас
• We would like to thank our army of testers for providing valuable feedback: generic_placeholder_name, Lomk, TheScrasse, vinfat, codelegend, BucketPotato, ajit, manish.17, Dragonado, anmolagarwal999, Lihwy, kryptai, ak2006 and brj!
• Thanks to nandini.maroo and akcube for helping with the poster design.
• And finally, we would thank MikeMirzayanov for the platforms Codeforces and Polygon without which all this would not be possible.

We hope you enjoy this contest!

UPDATES

Score Distribution: 500 — 750 — 1250 — 1750 — 2250 — 2750
Editorial is out.

Winners

Congratulations to all the winners for such an amazing performance.
Global Top 5
1. tourist
2. ksun48
3. noimi
4. jiangly
5. Um_nik

Official Top 5
1. JrNTR
2. YinJinRun
3. Remakee
4. see_wo
5. HowtobeRed

We will send a CF personal message to the winners of the T-shirts soon.

PRIZES

The following twenty lucky participants receive a T-shirt:

• Top 10 Indian participants.
• Random 10 from top 100 (ranks 11-100) Indian participants.

These ranks are determined from the combined unofficial rank list. People who have their Country set to India in their CF profile will qualify as Indian participants.

We are giving T-shirts to Indian participants only to avoid logistic issues that we have to face during international delivery. We apologize for this limitation, we will try our best to bring international prizes too from next year.

Thanks to NEAR for supporting this round, details can be found in this post.

We will hold Codeforces Round 794 (Div. 1) and Codeforces Round 794 (Div. 2).

• Contest URLs: https://codeforces.net/contest/1685, https://codeforces.net/contest/1686
• Unusual start time: 25.05.2022 20:35 (Московское время)
• Duration: 135 minutes
• Number of Tasks: 6 for Div2, 5 for Div1
• Rated range: $$$(-\infty, 1899]$$$ for Div2, $$$[1900, \infty)$$$ for Div1
• Writer: antontrygubO_o
• Testers: golions, oleh1421, Geothermal, nor, TheScrasse, timreizin, emorgan, Um_nik, 244mhq, Kuroni, ak2006
• VIP-tester: errorgorn
• Coordinator and author of one problem without which round would be unbalanced: dario2994
• Creator of the amazing Codeforces and Polygon platforms: MikeMirzayanov

The point values will be:

Div2: 500 — 1000 — 1500 — 2000 — 2500 — 2500

Div1: 500 — 1000 — 1500 — (1500 + 1500) — 3500

We are looking forward to your participation!

UPD 1: Thanks to NEAR for supporting this round, details can be found in this post.

UPD 2: Editorial

UPD 3: Congratulations to winners!

Div1:

1. heuristica

2. jiangly

3. ecnerwala

4. gamegame

5. maroonrk

Div2:

1. lmcutezzz

2. Teating_

3. lunchbox

4. Nida1097

5. demacia

Hello Codeforces!

On May/23/2022 17:35 (Moscow time) Educational Codeforces Round 129 (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!

UPD: Editorial is out

Hi Codeforces!

I am pleased to invite you to Codeforces Round #793 (Div. 2), which will take place on 22.05.2022 17:35 (Московское время). You will be given 6 problems and 2 hours to solve them.

The round will be rated for participants of Division 2 with a rating lower than 2100. Division 1 participants can participate unofficially in the round.

All problems in this round were prepared by me and rivalq. We have worked on this round for a long time and hope you find every problem interesting.

I would like to thank:

• antontrygubO_o for marvellous coordination of the round.
• errorgorn, kclee2172, AmShZ, nvmdava, TheScrasse, aryanc403, koderkushy, PurpleCrayon, nor, AlperenT, towrist, ExplodingFreeze, conquered, naresh0839, The_Hawkeye, Siuuuuu_7, GuptaSir, sp005, obliviousz, davidgarg20, ak2006, and the_hyp0cr1t3 for testing this round and giving really valuable feedback.
• MikeMirzayanov for the amazing Codeforces and Polygon platforms!
• You for participating and upvoting.
• NEAR for supporting this round, details can be found in this post.

Score Distribution:

750 – 1000 – 1500 – 2000 – 2500 – 2750

Good luck and have fun! See you in the standings. Make sure to read the statements very carefully.

Thanks to ak2006, video editorials for some of the problems will be available on his channel after the round.

Congratulations to winners!!

Global Top 5:

1. jiangly, superfast AK!

2. Beduardo

3. SSRS_

4. neal

5. turmax

Official Top 5:

1. Beduardo

2. Brewess

3. Kizuna_AI

4. Focalors

5. csyakuoi

Special mention to AwakeAnay for the only Indian to AK the round!

UPD 1: Links to video editorials of Problem B and Problem C

UPD 2: Editorial for problems A-D is here.

UPD 3: Editorial for E is added.

UPD 4: Editorial for F is added.

Hi, Codeforces!

We are glad to invite you to Codeforces Round 792 (Div. 1 + Div. 2) which will take place on May/19/2022 17:35 (Moscow time). You will have 2 hours to solve 8 problems. The round will be rated for participants of both divisions.

I would like to thank those who made this round possible:

• Artyom123 и KAN for coordination and their active help
• gamegame, generic_placeholder_name, kpw29, physics0523, I_love_kirill22, I_love_teraqqq, SecondThread, vsinitsynav, SlavicG, flamestorm, snowysecret, KiruxaLight for testing and providing tons of useful feedback to make the round better
• MikeMirzayanov for such great platforms Codeforces и Polygon

We would also like to thank NEAR for supporting the round. This company is founded by former competitor AlexSkidanov. NEAR is built by many prominent competitive programmers, including twice ICPC champion eatmore and GCJ and TCO winner Egor.

• The participants who end up in the first 255 positions will receive prizes in NEAR coins. The participant on the first place will receive Ⓝ128, the next two participants will receive Ⓝ64, the next four participants will receive Ⓝ32, etc.

Score Distribution:

500 — 750 — 1250 — 1500 — 1750 — 2000 — 2500 — 3250

We really hope that you like the problems! Good luck!

Editorial: link

Hello, Codeforces!

I'm glad to invite you to Round 791 which will start at May/14/2022 12:35 (Moscow time). Please notice the unusual time.

There will be 6 problems in the round. Round is based on Team Olympiad in Lipetsk which is being held for the seventh time. Problems were proposed and prepared by iakovlev.zakhar, Kon567889, iura, andr1y, Masha237, welleyth and me. I would like to thank Aleks5d and KAN for CF round coordination and testers: Um_nik, 353cerega, errorgorn, Stepavly, divanik, nnv-nick, 4qqqq, to be continued...

Of course, I'd like to thank all Codeforces team for Codeforces and Polygon beautiful platforms!

I also would like to thank golikovnik, egneeS, dshindov and Inessa Shuykova (Lipetsk teams' coach) for preparing other Olympiad problems that haven't been taken for this round.

Thanks to NEAR for supporting this round, details can be found in this post.

Note that if you are an official participant of the Olympiad, you are not allowed to participate in this round.

Scoring distribution will be announced later.

Wish you good luck and high rating!

UPD.1 Scoring distribution: $$$500 - 1000 - 1500 - 1750 - 2250 - 3000$$$.

UPD.2 Congratulations to winners!

Official participants:

1. xiaoziyaooo

2. StickyFingers

3. mybing

4. huangweiliang

5. NewPC2022

Unofficial participants:

1. SSRS_

2. leaf1415

3. uwi

4. maspy

5. TripleM5da

UPD.3 Editorial is available here.

Hello Codeforces!

On May/13/2022 17:35 (Moscow time) Educational Codeforces Round 128 (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:

Harbour.Space takes over SWERC by winning gold and silver for the first time in its history and will go to the ICPC World Finals. Congratulations to all of our participants and coaches that made this a reality!

This is a very important moment in Harbour.Space and Codeforces long partnership, with 127 educational rounds being organized and a big Harbour.Space Scholarship Contest held on July 22th. We have selected contest winners (cum00, Meijer and amanbol) to form our current teams.

Since its creation, one of Harbour.Spaces’s goals has been to win SWERC and compete at a high level in the ICPC globally. On April 24th, that objective was accomplished when Harbour.Space’s team RAW POTS (read it backwards!) won the gold medal and the overall contest against Southwestern Europe’s top contenders.

Team Raw Pots — gold medal:

Maksym Oboznyi (MaksymOboznyi), Marco Meijer (Meijer), and Danil Zashikhin (cum00)

Team Kempirqosaq — silver medal:

Temirlan Baibolov (bthero), Dinmukhamed Tursynbay (DimmyT), and Amanbol Kanatuly (amanbol), ranked 4th and won a silver medal.

Team Harbour.Backspace — ranked 27th:

Anier Velasco (aniervs), Fadi Younes, and Ekaterina Podruzhko, ranked 27th.

The faculty, current students, alumni, and everyone involved with Harbour.Space would like to congratulate the winners and participants at SWERC 2021-2022 for their wonderful performance and hard work.

As usual, we are always excited to see Codeforces participants as our students here at Harbour.Space. That’s why we encourage you to apply to our latest apprenticeship program in partnership with Hansgrohe, as a Kotlin Developer until May 31st, 2022.

Harbour.Space University Team

UPD: Editorial is out

Hello Codeforces!

SlavicG, mesanu, MikeMirzayanov, Errichto, and I welcome you to Codeforces Round 790 (Div. 4). It starts on May/10/2022 17:45 (Moscow time).

The format of the event will be the same as before:

• 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.

Many thanks to the testers: timreizin, magnus.hegdahl, Adam_GS, KrowSavcik, qwexd, pseudocoder10, jampm, Neophiliatic, Codula and of course _Vanilla_.

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

Good luck!

UPD: the start of the round is delayed by 10 minutes.

UPD: Editorial is published!

Hello, Codeforces! ฅ(*`ω´*)ฅ

We are glad to invite you to take part in Codeforces Round 789 (Div. 1) and Codeforces Round 789 (Div. 2), which will be held on May/08/2022 17:35 (Moscow time).

The round will be rated for all participants from both divisions. Participants in each division will be offered 6 problems and 2 hours to solve them. Both divisions will share 4 problems.

The problems were written and prepared by funer, dark_light, FreshP_0325, Frank_DD, qsmcgogo, winterzz1, Sugar_fan, TomiokapEace and me.

Thank to:

• RedMachine-74 for excellent coordination of this round! And translating the statements to Russian.

• KAN for helping us to review and fix some statements.

• TomiokapEace for helping us to translate all the statements and tutorials to English.

• Sugar_fan for giving valuable advice and helping us to fix some statements.

• Elder_Giang, ddytxdy, zwezdinv, zarubin, olyazyryanova, marzipan, MichsSS, playf, TeaTime, gojira, plagues, AlexLuchianov, kpw29, Huah, Yzm007, Duck_sajin, Operation27, Venn, Nephry, Sugar_fan, errorgorn, Um_nik, TadijaSebez, Prokhor74, Grigoreva-Irina, Dragonado, lunaTu and jqdai0815 for testing this round and giving good advice.

• MikeMirzayanov and his Codeforces team for amazing systems Codeforces and Polygon!

• NEAR for supporting this round, details can be found in this post.

Here are some things I personally want to say. This is my second round. Three years have passed since the first round round 573 I held. Now I have graduated and worked. I like codeforces very much. Though I have already participated in work, haven't trained for a long time, my ability has degraded a lot, I will still come to codeforces to participate in the contest in my spare time. This time I also prepared some problems to propose a round, but for some reasons, most of them were rejected. In particular, one of my favorite problems was rejected because "many testers don't like it". I'm a little frustrated, but I also understand that the coordinator's job is to make the round better and more people like this round. I think it's a great honor to prepare round on codeforces and let so many people around the world try to solve the problem I prepared. I will accumulate some more interesting ideas for the next round and try to make more people like the problems I prepared.

I'd like to express my great gratitude to my friends for preparing this round with me, I don't think I can prepare this round alone without them. I really appreciate having the support of my good friends in my round.

In addition, the three naughty cats mentioned in the statement.(*=｀ω´=)ﾉ I understand that I shouldn't post pictures irrelevant to the statement, so I post it here ↓

Finally, I hope you like the problems in this round, good luck and have fun!(≧ω≦)/

The score distribution will soon be published.

UPD1: Although our coordinator allows to post the PDF of Chinese statements in the contest material, it seems that codeforces does not allow it. We are only allowed to post something after the round. So we will still post Chinese tutorials after the round.

UPD2: List of contributors is a bit changed, and the score distribution will be:

• Div.2: 500 — (750 + 1000) — 1250 — 2000 — 2000 — 2750

• Div.1: 500 — 1250 — 1250 — 2000 — 2500 — 3500

UPD3: Note that the score of the last problem of Div.1 has changed, 4000 → 3500.

UPD4: Editorial is out, and Chinese Tutorial will soon be published.

UPD5: Chinese Tutorial is out.

UPD6: Congratulations to the winners!

Div.1:

1. maroonrk

2. tourist

3. eecs

4. ainta

5. duality

Div.2:

1. NiNiV

2. WA_On_Pretest2_Forces

3. ouql

4. KroosTheKeenGlint

5. jialiang250