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, I_Remember_Olya_ashmelev and Aris_244_ 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!

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 13:05 (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.
• 1-gon, voidmax, alexX512, ijxjdjd, m371, makogon2907, chctxdy68, Hemose, Hinai_Paulette, Omkar, 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!

Hello, Codeforces!

Welcome to the ICPC Communication Routing Challenge powered by Huawei!

This challenge edition is very special, as it will be happening in conjunction with the ICPC World Finals! For those who are not participating in the finals — ICPC and Codeforces are offering a unique chance to compete during a 4-day Challenge Marathon and win amazing prizes from Huawei!

ICPC Challenge Marathon (open to public, unrated): October 9-13, 2021, 00:00 UTC:

This time we’re delighted to provide you with a future-oriented topic – routing algorithms for next-generation communication. During this Challenge we will provide you with a super-large inter-satellite optical network to properly plan message paths, to reduce communication latency and improve resource utilization. However, finding the optimal path in a network with limited resources is an NP-hard problem. Considering the physical constraints of optics and circuits, our algorithm faces greater technical challenges:

• How can we model and abstract device constraints and design algorithms in the most appropriate way?
• Is there an algorithm that takes almost the same time to calculate routes as the network scale increases?
• Is there any way to obtain the theoretical optimal solution in a short period for ultra-large networks?

We hope that these satellite communications challenge questions can help you understand the problems that Huawei's software algorithm researchers face every day. All the best!!!

Prizes

For 3-hours onsite ICPC World Finals Challenge Huawei will provide prizes to the winners in 2 groups of participants:

• Group 1: TOP 30 ICPC World Finalists, who participate individually:

  1st-10th place	HUAWEI MATE 40 Pro
  11th-20th place	HUAWEI MatePad Pro
  21st-30th place	HUAWEI WATCH 3 Pro

• Group 2: TOP 9 ICPC World Finals Coaches and Co-Coaches, who participate individually:

  1st-3rd place	HUAWEI MATE 40 Pro
  4th-6th place	HUAWEI MatePad Pro
  7th-9th place	HUAWEI WATCH 3 Pro

For 4 days online Challenge Marathon, Huawei will provide prizes to TOP 30 individual participants:

* The 1st place winner will get additional bonus in amount of 5000 USD. If the bonus cannot be transferred to the winner due to any reason, it may be replaced by a prize of the same value.

If the allocated Huawei Challenge prize cannot be delivered to your region for any reason it may be replaced by another prize of the same value (if no legal restrictions), at the discretion of the sponsor.

By participating in this Challenge, you agree to the Challenge Rules and Conditions of Participation

Good luck to all participants!

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.com/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:

• 1-gon for coordinating the round and helping us with the problems.
• mnbvmar, gamegame, dorijanlendvaj, tnowak, Jasiekstrz, ijxjdjd, shxgun, 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. peehs_moorhsum

4. ecnerwala

5. Molewus

Div2.

1. ChenRui

2. rainboy

3. OguriCap

4. _October

5. Dallby

UPD4: Editorial is out!

Hello, Codeforces!

On Sep/12/2021 17:35 (Moscow time) we will host Codeforces Global Round 16.

It is the fourth 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 shishin and Artyom123.

We would like to thank these people:

• isaf27, the one who did a lot of things for the round to happen
• Shinchan01, Absyarka, Ziware, ijxjdjd, m371, Kotehok3, 221,physics0523, Igorbunov, kpw29, Kirill22, 1-gon, pashka for testing
• Kirill22 for submitting many different solutions
• 1-gon for being a VIP tester and his hilarious greetings in russian
• kpw29 for spending much time discussing the problems with me
• physics0523 for making researches about the tasks (as he always does)
• MikeMirzayanov for Codeforces and Polygon platforms and for his immeasurable contribution to the development of the community!

You will have 2.5 hours to solve 8 problems. As always, we highly recommend reading all problems. Moreover, we really hope you upsolve the problems after the round, there are some interesting things to find out!

One of these problems is interactive, please see the guide of interactive problems if you are not familiar with it.

Score Distribution:

500 — 750 — 1000 — (750 + 1000) — 2000 — 2500 — 3000 — 3750

Editorial:

The editorial

Winners

System testing finished, congrats to the winners!

1. Radewoosh
2. tourist
3. QAQAutoMaton
4. jiangly
5. ksun48
6. Alice_foo_foo
7. He_Ren
8. Benq
9. tatyam
10. hitonanode

Hello Codeforces!

On Sep/08/2021 17:35 (Moscow time) Educational Codeforces Round 113 (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!

Congratulations to the winners:

69 ^nice successful hacks and 304 unsuccessful hacks were made in total!

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

UPD: Editorial is out