صباحو (Good Morning), Codeforces!

I'm glad to invite you to Codeforces Round 746 (Div. 2), which will be held on Oct/03/2021 17:35 (Moscow time).

This round is rated for the participants with rating lower than 2100.

You will be given 6 problems and 2 hours to solve them. All problems were prepared by me and Bakry.

One of the problems will be interactive. So, it is recommended to read the guide on interactive problems before the round.

I would like to thank:

• antontrygubO_o, for a lot of things (awesome coordination, suggestion for one of the tasks, helping in preparation, rejecting only not interesting tasks, a lot of useful discussions).

• KostasKostil for one of the tasks and antontrygubO_o for preparing it.

• YahiaSherif, ZeyadKhattab, mahmoudbadawy, Uzumaki_Narutoo, _zaher_ for discussing and testing the problems.

• Our army of testers 244mhq, TripleM5da, Naseem17, Mohammad_Yasser, ZerooCool, compiler_101, TheSawan, IsaacMoris, Mohamed.Sobhy, AhmedEzzatG, Ahmed_AIansary, Evro, Sisy, G.A.T.C, mennafadali, Khater, It_Wasnt_Me, DAleksa, Samez, soba, O_E, AhmedZ, AshrafEzz, Urvuk3, Mo2men, Ahmad.houmani.

• MikeMirzayanov, for the amazing Codeforces and Polygon platforms.

The statements are short and we have tried to make the pretests strong. I encourage you to read all the problems.

For people who don't like stories, you will find all the stories written in italic you can skip them safely.

This is our first official round on Codeforces. We are sincerely looking forward to your participation. We hope everyone will enjoy it.

Good luck and see you in the standings!

UPD:

Score Distribution: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$2000$$$ — $$$2500$$$ — $$$(1750-1750)$$$

UPD1: Editorial is out!

UPD2: Winners

Div. 1 + Div. 2

1. LayCurse

2. SSRS_

3. qazsxdew

4. peti1234

5. dlalswp25

Div. 2

1. qazsxdew

2. CrTsIr

3. tsukigakirei

4. FangZeLi_AK_IOI

5. RiCHEPCPR

Hi Codeforces ଘ(੭*ˊᵕˋ)੭* ੈ♡‧₊˚!

We're delighted to invite you to COMPFEST 13 — Finals Online Mirror (Unrated, ICPC Rules, Teams Preferred) on .

All problems were written and prepared by hocky, steven.novaryo, rama_pang, JulianFernando, yz_, Panji, richiesenlia, Sakamoto, and markus_geger.

I would also like to thank:

• KAN for helping to host the mirror round;
• (AVM.Martin, Ace_02), Berted, ardan, wijayareynaldo, and bukanYohandi for testing the round locally and improved the problems in early phases;
• UWr Kobor 53 (w0nsh, kobor, Fly_37), Almost Retired (KAN, Um_nik, Ekler), and errorgorn for testing the round and their really useful feedbacks;
• Universitas Indonesia, all the local committees, administrators, and managers of the whole COMPFEST event;
• prabowo for observing the contest;
• fushar for the Judgels platform used in the official contest; and finally
• MikeMirzayanov for the great Codeforces and our lovely Polygon!
• Extra thanks for rama_pang and steven.novaryo for working hard night 🌚 and day 🌞 making sure the problems are well-prepared (the contest wouldn't exist without their hands).

The duration will be 5 hours, consisting of 13 problems. You can register individually, but teams are preferred. You may expect relatively easier problems than ICPC Regional Contests. You may code parallely with several computers with your teammates and use prewritten codes and templates.

COMPFEST itself is an annual event hosted by Universitas Indonesia. It is the largest student-run IT event in Indonesia and competitive programming contest is one of the competitions hosted.

We've put great effort into preparing this contest and we hope that you will enjoy it. See you! ありがとう~! 🐾

UPD: Editorial is out!!! Editowial UωU

Congratulations to our top 5!

1. leziren (jqdai0815, TLE, Rewinding)
2. heno239
3. bubble (riantkb, nuip, mtsd)
4. gisp_zjz
5. We Won it 0 time (aarr, afterall, Amoo_Safar)

Hello, everybody!

We would like to invite you to participate in the Mirror of The ICPC World Finals Moscow Invitational Contest. The original contest was made for the teams who cannot come to The World Finals in Moscow. They were competing for the medals and glory. The Invitational contest has already passed and the results will be revealed on October 5th.

The mirror contest will be held by almost standard ICPC rules with 10 to 14 problems. The difference from the traditional ICPC format is that your team can use three computers instead of one. The problems are expected to be of The World Finals difficulty. Also, the round will be unrated!

The problemset was prepared by NERC Jury Team with the help of many other people. The chief judge is Roman elizarov Elizarov. The jury members are Pavel PavelKunyavskiy Kunyavskiy, Georgy kgeorgiy Korneev, Evgeny eatmore Kapun, Ilya izban Zban, Niyaz niyaznigmatul Nigmatullin, Vasiliy SirShokoladina Mokin, Daniil danilka.pro Sagunov, Gennady tourist Korotkevich, Oleg snarknews Hristenko, Egor Egor Kulikov, Borys qwerty787788 Minaev, Pavel pashka Mavrin, Mike MikeMirzayanov Mirzayanov, Anton Paramonov, Bruce bmerry Merry, Zachary Friggstad Friggstad, Jakub Wojtaszczyk, David Van Brackle, and myself. (I hope I haven't missed somebody. :P)

I hope you will like the contest! Good luck and have fun!

UPD: The editorial is available here.

Hello Codeforces!

CQXYM and I are glad to invite you to Codeforces Round 745 (Div. 1) and Codeforces Round 745 (Div. 2), which will be held on Sep/30/2021 13:15 (Moscow time). Note the unusual time of the round.

Each division will have 6 problems and 2 hours to solve them. All problems were written and prepared by CQXYM and me. The round will be rated for both divisions.

We would like to thank:

• Aleks5d for his excellent round coordination and many useful suggestions that greatly help with preparation.
• Monogon, voidmax, alexX512, ijxjdjd, wxhtzdy, makogon2907, 16204, Hemose, Hinai_Paulette, H4ckOm, 4qqqq, FBKdaisuki, kassutta, Mo2men and pkpawan for testing the round and providing useful feedback.
• MikeMirzayanov for great platforms Codeforces and Polygon.
• And you, for participating!

This is our first round, and great efforts have been put into preparing this round. Were you to kindly participate in this round, we would be very grateful and hope you will enjoy it.

Good luck!

UPD: Here are the scoring distributions:

Div. 1: $$$500$$$ — $$$1000$$$ — $$$1750$$$ — $$$2000$$$ — $$$3500$$$ — $$$3500$$$

Div. 2: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$1750$$$ — $$$2500$$$ — $$$2750$$$

And we would also like to thank Um_nik for testing the round.

UPD2: Editorial is out!

UPD3:

Winners

Congratulations to the winners:

Div1:

1. nutella_waxberry

2. maroonrk

3. Radewoosh

4. Karry5307_AK_NOI2024

5. hos.lyric

Div2:

1. _ywy_c_asm_

2. lpf666

3. Fuzen

4. leap_frog

5. OguriCap

Hi Codeforces!

Today I'd like to introduce the new Competitive Programming Hall of Fame project that is available at cphof.org

Background

A long time ago I've noticed that there is no single source of information with the results of previously held large programming competitions. Moreover, plenty of older championships don't maintain their websites anymore, and it becomes hard or even impossible to find any details about them, which is pretty sad. So I've decided to create Competitive Programming Hall of Fame.

About the project

Competitive Programming Hall Of Fame is a project created to preserve the history of international championships in competitive programming. This website collects the results of the final stages for both worldwide and regional contests. By international championship we mean a contest consisting of several stages available for competitors from more than one country.

The project is mostly focused on worldwide contests that have onsite finals, and on smaller championships with no more than 100 finalists. For each of the participants there is a profile page with a timeline and track record of their performance in various final events.

We divide all championships into 5 categories: Worldwide Onsites (Major Competitions), Worldwide High School and Collegiate Onsites, Worldwide Online Championships, Regional Contests, and Local Contests.

How can you contribute

You can contribute to the Competitive Programming Hall of Fame by providing information that is missing or wrong on the website. Please use either the form at cphof.org/contribute or comments/DM at Codeforces for it.

We will be especially happy if you find and share something from this list:

• Information about any international competitive programming championship that is missing on the website;
• Wrong data on the website, duplicate profiles for the same person, or profiles of different people mistakenly merged into one;
• Wrong name spelling;
• Team members and prizes for ICPC World Finals 2005 and earlier;
• Standings (with the number of problems solved and penalty) for ACM-ICPC World Finals 2009, and for 1998 and earlier;
• Team members for Google Hash Code and Challenge24 (any year).

Acknowledgments

I express my appreciation to aropan (clist.by), eduardische (stats.ioinformatics.org), kostka (kostka.dev), snarknews (snarknews.info), zibada (zibada.guru), unknown author of www.go-hero.net, MikeMirzayanov, and all the authors of (Codeforces) blogs with lists of finalists for creating resources that share our mission to preserve the history of competitive programming contests. Without them our website couldn't have as much detailed data as it has today. Also, I would like to say thanks to aropan, DAle, Romka and tourist for some helpful pre-launch advice.

Feel free to spread the word about this website, and to use its materials in your blogs, video streams, and social pages.

Hello Codeforces!

Sorry for a bit delayed English announcement, we are glad to invite you all to Codeforces Round 744 (Div. 3), third division round held on Sep/28/2021 17:35 (Moscow time). This round was prepared by me and MikeMirzayanov and we hope that you'll find the problems interesting and enjoy solving them.

I would like to thank MikeMirzayanov for helping me with both writing and preparing the problems for this round. Since it's the second Div. 3 round held I'm involved in but only the first one I'm preparing problems for from zero all the way to the end, without his guidance it would've taken much more of my time.

Also special thanks to nizamoff, andreumat, QAZZY, Vladosiya, CtrlAlt, vladmart, Igorjan94, okwedook, ashmelev and Aris for testing the round and giving their feedback on the problems as well as to Gassa and geranazavr555 for proofreading and correcting the statements. This round is very noticeably better than it could've been without your contribution. And last but not least, thanks to everyone who'll be participating! This round contains 7 to 8 problems and is expected to be of decent level of difficulty for participants with ratings up to 1600. However, all of you who wish to take part and have a rating 1600 or higher, 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 tried to make tests strong enough but it doesn't at all guarantee that open hacks phase will be pointless.

You will be given 7-8 problems and 2 hours 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 trusted participants of the third division, you must:

• take part in at least two 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.

Good luck and have fun!

UPD: Editorial is out!

Hello Codeforces!

On Sep/20/2021 17:35 (Moscow time) Educational Codeforces Round 114 (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!

Congratulations to the winners:

Congratulations to the best hackers:

And finally people who were the first to solve each problem:

UPD: Editorial is out

Hello.

Sorry for it. Actually, right now I don't have any idea why testing is so slow now. Obviously, it doesn't work as expected. It is not because of problems. So please don't blame writers or coordinators. I'm investigating the reason, but don't see it now.

I myself am very upset and I apologize to the authors, coordinator, and participants. I will do my best to find the cause and fix it. Surprisingly, we haven't made any big changes to this part of the system lately. But something went wrong.

Mike.

UPD: https://codeforces.net/blog/entry/95081#comment-841873

Hello Codeforces!

Asymmetry and I are glad to invite you to Codeforces Round 743 (Div. 1) and Codeforces Round 743 (Div. 2), which will be held on Sep/18/2021 17:35 (Moscow time).

Each division will have 6 problems and 2 hours to solve them. All problems were written and prepared by Asymmetry and me. The round will be rated for both divisions.

We would like to thank:

• Monogon for coordinating the round and helping us with the problems.
• mnbvmar, gamegame, dorijanlendvaj, tnowak, Jasiekstrz, ijxjdjd, phattd, lcaonmst, -_-INV4D3R-_-, ToxicPie9, Shinchan01 and Krzaq for testing the round and providing useful feedback.
• ToxicPie9 for being a VIP tester.
• finally, MikeMirzayanov for great platforms Codeforces and Polygon!

We've put great efforts into preparing this round and we hope that you will enjoy it.

Good luck!

UPD: We would also like to thank Ari for testing the round and KAN for translating the statements into Russian.

UPD2: Here are the scoring distributions:

Div. 1: $$$500$$$ — $$$1250$$$ — $$$1750$$$ — $$$2500$$$ — $$$2500$$$ — $$$3250$$$

Div. 2: $$$500$$$ — $$$1000$$$ — $$$1500$$$ — $$$2250$$$ — $$$2750$$$ — $$$3500$$$

UPD3: We are sorry that the round became unrated due to the long queue. We hope that you enjoyed the problems anyway.

Winners

Congratulations to the winners!

Div1.

1. tourist

2. Benq

3. VivaciousAubergine

4. ecnerwala

5. Molewus

Div2.

1. ChenRui

2. rainboy

3. OguriCap

4. _October

5. Dallby

UPD4: Editorial is out!