By Rhodoks, 3 weeks ago,

Hello Codeforces!

We are glad to invite you to our Codeforces Round Codeforces Round #810 (Div. 1) and Codeforces Round #810 (Div. 2) which will be held on 24.07.2022 17:35 (Московское время). This round will be rated for participants of both divisions. Participants in each division will be offered 5 problems and 2 hours to solve them. The two divisions will share 3 problems.

The problems are prepared by me and zxyoi. We hope that everyone will enjoy this round!

We are sincerely thankful for the help provided by:

We tried our best to have detailed, clear, and short statements. I think that anyone can find some interesting problems in this contest. We suggest to read all the statements.

The score distribution will be announced later.

Wish you good luck and high rating!

UPD

For some reason, we have removed one of our problems. So now participants in each division will be offered 5 problems and 2 hours to solve them.

The score distribution is:

Div2: $500-1000-1500-2000-3000$

Div1: $500-1000-1750-2000-2750$

We have some more testers now, let's thank them!

UPD2

We adjusted our score distribution slightly.

UPD3: the Div. 1 part of the round is declared unrated.

UPD4

Sorry for the late editorial.

UPD5

Congratulate to winners:

Div1

Div2

• -3405

By Errichto, 5 weeks ago,

Hi. I'm organizing an online IOI-preparation camp in collaboration with Huawei. Every day will be a 5-hour virtual contest, then my problem analysis, and sometimes a lecture. There will be at least 4 contests and 2 lectures.

We will do some old IOI contests (2013?) from the IOI archive, CEOI (2015-2016?), or maybe JOI/JOISC — to be decided this weekend. I don't want to do recent years like 2021 because most participants already covered it. The example lecture topics are those from Range Queries or Trees in Usaco Guide Platinum.

The camp is free for IOI 2022 participants. For everybody else, the video recordings will be posted on Youtube after the camp. By participating you get the live experience (Discord, asking questions, competing with others, leaderboards).

Dates: 25.07-2.08 (updated)
Time of every analysis/lecture: 14:00 UTC / 16:00 CEST
Price: free for IOI participants, 40 USD for everybody else
Platform: Discord & Codeforces & uj.oz (?)

How to register?

Big thanks to Huawei UK R&D for sponsoring this camp.

EDIT: I'm now aware of CEOI collision. There's nothing I can do about it :(

Schedule:
25.07 — CEOI 2016 day 1
26.07 — CEOI 2022 day 1 + lecture
27.07 — CEOI 2016 day 2
28.07 — CEOI 2022 day 2
29.07 — lecture + homework
weekend off
1.08 — CEOI 2017 day 1
2.08 — CEOI 2017 day 2

Participants voted to cover CEOI instead of IOI to avoid problems that they already know.

• +448

By awoo, history, 4 weeks ago, translation,

Hello Codeforces!

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:

WORK & STUDY OPPORTUNITY IN BANGKOK — B.GRIMM POWER x HARBOUR.SPACE UNIVERSITY

B.GRIMM POWER has partnered with Harbour.Space University to offer Bachelor's and Master’s degree scholarships in Data Science as well as work experience in one of the main infrastructure developers in Thailand.

B.Grimm Power PCL (B.Grimm Power), is a Thailand-based electricity generating and distribution energy company. B.Grimm Power is involved in the development, financing, construction and operation of power plants. Its product portfolio includes solar, hydro, wind power, and Diesel.

We are looking for various junior to mid-level candidates to work on solving tasks in the following fields:

• Data analysis
• System integration
• AI
• Forecasting Modeling

All successful applicants will be eligible for a 100% tuition fee scholarship (22.900 €/year) provided by the B.GRIMM POWER.

CANDIDATE’S COMMITMENT

Study Commitment: 3 hours/day

You will complete 15 modules (each three weeks long) in one year. The daily class workload is 3 hours, plus homework to complete in your own time.

Work Commitment: 4+ hours/day

Immerse yourself in the professional world during your apprenticeship. You’ll learn from the best and get to apply your newly acquired knowledge in the field from day one.

REQUIREMENTS:

• Industry experience
• International exposure
• Eager to learn
• Entrepreneurial mindset
• (Thai Language is a plus, not a must)
Apply Now

UPD: Editorial is out

• +166

By BucketPotato, 4 weeks ago,

Hi Codeforces,

We're excited to invite you to Codeforces Round #809 (Div. 2), which will take place at 18.07.2022 17:35 (Московское время). All problems were created and prepared by lunchbox, lce4113, and me. It will be rated for all participants with ratings lower than 2100.

Thanks to the people that made this round possible:

You will be given 2 hours to solve 5 problems, one of which will be divided into 2 subtasks. The scoring distribution will be announced later.

UPD: The scoring distribution will be $500 - 1000 - 1250 - (1000 + 1250) - 2250$.

UPD2: The editorial has been posted at https://codeforces.com/blog/entry/105008.

UPD3: Winners

#### Everyone

• +472

By waaitg, history, 4 weeks ago,

Hello, Codeforces!

Imakf and I are glad to invite you to Codeforces Round #808 (Div. 1) and Codeforces Round #808 (Div. 2), which will take place on 16.07.2022 17:35 (Московское время). In both divisions, you will be given 6 problems and 2 hours to solve them all.

We would like to thank:

Score distribution will be announced before the round.

Wish you all wouldn't gain negative ratings in this round! (This is theoretically possible XD)

UPD1: Score distribution is

Div 2: $500 - 1000 - 1500 - 1750 - 2250 - 3000$

Div 1: $500 - 750 - 1250 - 1750 - 2500 - 3250$

UPD2: Editorial

UPD3: Congratulations to the winners!

Div 1

Div. 2

• +280

By MarkBcc168, 5 weeks ago,

Hello Codeforces,

We are glad to invite you to Codeforces Round #807 (Div. 2), which will be held on 15.07.2022 16:35 (Московское время). As usual, the round will be rated for participants with ratings lower than 2100, while those who have higher ratings are encouraged to participate unofficially. Please note the unusual start time.

You will be given 6 problems to be solved in 2 hours and 15 minutes. There may or may not be interactive problems, so you are encouraged to prepare in case they do appear by reading this guide.

The round is authored by abc241 and me, while joining us is also inwbearX who contributed significantly to the preparation. This is our first time setting rounds in Codeforces, and it wouldn't be possible if there were no support from the following people.

The score distribution is $500$ — $1000$ — $1250$ — $1750$ — $2500$ — $3000$.

We are looking forward to your participation. Good luck and enjoy our round!

Update: the editorial is up!

Update 2: Winners!

Div. 2

Div. 1 + Div. 2

• +280

By mesanu, history, 5 weeks ago,

Hello Codeforces!

SlavicG, flamestorm, MikeMirzayanov and I want to invite you to Codeforces Round #806 (Div. 4).

It starts on 12.07.2022 17:35 (Московское время).

The format of the event will be identical to Div. 3 rounds:

• 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: TimDee, Gheal, Max_Calincu, down, _Vanilla_,sandry24, jampm, haochenkang, tibinyte, Etherite.

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

Good Luck!

Update: Editorial

• +151

By Gol_D, history, 5 weeks ago,

Hello! Codeforces Round #805 (Div. 3) will start at Jul/10/2022 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, SixtyWithoutExam and me Gol_D.

Also many thanks to turmax, Crescendo, antonis.white, Ronnie007, okwedook, Bugman, Kavaliro, antoshkin, omikad, yorky, Jostic11, Ziware, Kniaz, andrey.starodubtsev, Spaggetti and aniervs for testing the contest and valuable feedback.

Good luck!

UPD: Editorial

• +236

By awoo, history, 5 weeks ago, translation,

Hello Codeforces!

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:

Hey, Codeforces!

Welcome to the 131st educational round hosted by Harbour.Space and Codeforces.

Quite exciting, isn’t it? Now it's time for you to dive deeper into the competitive programming world with the 10 days intensive Summer Camp organized by Harbour.Space and Leagues of Code.

Don’t forget about the discounts for participating in our Summer Camp. Every member of the Codeforces community gets a 30% discount for on-site participation or a 50% discount for online participation with promo-code CFLOC2022.

Our Summer Camp is a training program that will teach participants competitive programming. It will take place in Barcelona and online on July 18-29, both participation formats are available.

We are inviting students ages 10 to 24, interested in improving their skills or seeking intensive, high-level training prior to the IOI. Teachers in the camp will be ICPC World Final Silver medalist mhq, SWERC 2022 Winners MaksymOboznyi, ICPC World Final Champion pashka and others. Participants will be divided into classes based on their level and previous experience. Classes will be held in English.

Good luck with the round!

UPD: Editorial is out

• +218

By MikeMirzayanov, 6 weeks ago,

Hello, Codeforces.

We have exciting news! Look at the logo. See the changes?

Yes, we are happy to announce our new sponsor and partner – the TON Foundation!

We appreciate their support!

The Open Network (TON) is a fully decentralized layer-1 blockchain designed by Telegram to onboard billions of users. The TON Foundation is aimed to further develop and advance the TON Blockchain and its related products for a mass audience.

Andrew Rogozov, founding member at the TON Foundation, says, "We strongly believe in the idea of competitive programming itself, because it is in the TON Blockchain DNA." The TON Blockchain protocol was designed by Nikolai Durov — who is a two-time ICPC world champion, a three-time IMO gold medalist, a multiple IOI medalist, and a co-founder of Telegram — and other winners of international competitions. Now the TON Blockchain core team consists of winners of blockchain contests held by Telegram.

The TON Foundation has already supported the CodeTON Round 1 earlier in March 2022. More than 22K users were registered, and 12K participants made at least one submission. "Codeforces is an unparalleled platform for developing the programming skills of coders all over the world. We are of one mind with the Codeforces team that such contests reveal a treasury full of talents," adds Andrew Rogozov.

I send rays of gratitude to Telegram and personally to Pavel Durov, who has supported our community for many years. With this help we have come a long way — we have run hundreds of rounds, developed the ecosystem, our community has grown hundreds of times. And we are moving forward! Support from the TON Foundation pleases with its succession.

I'm happy to announce that starting July 2022, we have the option to increase problem writer payouts. Hooray!

• Div. 2: $300; • Div.1 + Div. 2:$600;