UPD: Special thanks to Mikhail awoo Piklyaev for help with translation and problems discussing, Maksim Neon Mescheryakov for problems discussing, Artem Rox Plotkin, Daria nooinenoojno Stepanova and Tommy STommydx Li for testing the round!

UPD2: Editorial is published!

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Hello! Codeforces Round 590 (Div. 3) will start at Oct/01/2019 17:35 (Moscow time). You will be offered 6 or 7 problems (or 8) 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 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. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 or 7 (or 8) problems and 2 hours 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 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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of my work. Thanks to my good friends Mikhail awoo Piklyaev, Maksim Neon Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

I also would like to say that participants who will submit wrong solutions on purpose and hack them afterwards (example) will not be shown in the hacking leaders table.

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Dear Friends!

If you dream of realizing your ideas in new technologies and products used by a third part of the world's population — join Honorcup Marathon. It will be an unrated round for individual participation, as well as for teams of up to three people.

You will develop a quite challenging task without exact solution. Your solution with show up your programming skills, research and data analysis abilities.

At stake: we have Huawei devices for the top 3 winners, as well as 10,000 USD for top 1.

And, of course, TOP 80 participants will get a hoodie with Huawei Codecraft logo! During registration don’t forget to mention your size and home address for delivery. Well performed participants will be invited to get highly paid 3 months contracts in Moscow, St. Petersburg, Nizhny Novgorod, Novosibirsk, Minsk or in China (including transportation & accommodation expenses covered).

We accept solutions before October 14th, 20.59.59, (Moscow time).

We will ask winners to provide the source code and description of the solution; the details can be discussed in a phone call. In case of reasonable doubt about the violation of the rules, we reserve the right to transfer the prize to the next participant. Thank you for understanding!

Don’t miss your chance. Good luck to all!

Hi folks,

The problem set from 2019 Fall Waterloo Local Contest that was held this Sunday will be available in the gym today in roughly 8 hours (timedate link).

This is an individual contest that contains 5 problems with 3 hours to solve them. It's good for both div 2 and div 1 participants — at least 3 problems should be accessible for div 2.

Div 1 participants are especially invited to solve problem E — so far only three people solved E.

GL&HF

UPD: Registration is open

UPD: Solution sketches are available at https://www.dropbox.com/s/hs9oy0y9ep0nmmq/Solution%20Sketches.pdf?dl=0

다시 만나서 반가워요, 코드포스! (Nice to see you again, Codeforces!)

I'm again happy to introduce you to Codeforces Round #589 (Div. 2). Please look at following information for details:

• This contest will take place on Sep/29/2019 16:05 (Moscow time).
• The round will be rated for all Division 2 participants.
• There are 6 problems and you will have 2 hours to solve them. Score distribution will be announced later.

The listed handles below are contributors. Thank you for all who listed!

• Main author: McDic — I made and prepared all problems.
• Coordinator: arsijo — He is my coordinator again.
• Early phase testers: dorijanlendvaj tfg Lawali — They are early phase testers. They mostly focused on test data.
• Late phase testers: Kuroni imbr92 Redux Dr_Park Savior-of-Cross TOPCYBERFLOWER _overrated_ antontrygubO_o raiden1943 — They are late phase testers. They gave problem difficulty/quality feedback by virtual participation.
• Codeforces Team: MikeMirzayanov and his team — They are working super hard to make Codeforces and Polygon great! Especially I love Polygon's framework! Thank you!

For this contest, I tried to improve following things:

• Reasonable difficulty: At my last contest, less than 200 official participants managed to solve at least one of DEF. Especially, 1182D's problem difficulty rating is 2500 and 1182F's problem difficulty rating is 2900(no official solvers!). This is not good for Div.2 participants. In other words, my first contest was hell. So this time, I tried to make my second contest to have more reasonable difficulty than my first contest.
• Stronger data: There were 300+ successful hacks and almost 2000 sysfails at 1182B. At this time, I splitted testing phase into early phase and late phase. I'm bit worried, but I believe data will be stronger than my last contest.
• Compact statement: I remember many people complained about 1182C's super complex statement. I made very compact statements for this round. There is no problem with more than 10 lines of statement(except I/O section) in this contest.

I hope everyone can enjoy my second contest. Thanks in advance!

UPDATES:

1. If you want to discuss problems in chat after contest ends, come https://discordapp.com/invite/algorithms and you can enjoy discussion.
2. I have deleted my last problem(G) from this contest during testing period. I really wanted to include that beautiful problem in my contest, but nobody solved that problem for a week. That problem will be appeared in another Div.1 contest.
3. Scoring distribution is 500(A)-1000(B)-1250(C)-1750(D)-2250(E)-2750(F).
4. Editorial: https://codeforces.com/blog/entry/70162
5. Congratulation for winners!

WINNERS (updated):

1. PositionZero
2. supy_2
3. hitman623
4. lzqaq
5. cwise
6. LittleBeetle
7. Tsypkokokokoko
8. i_love_gnar
9. 8-_-8 (handle mentioning is not working on his handle)
10. wdk1745

Hi everyone!

This summer I participated in the program AddisCoder 2019. It is a five-week intensive summer camp where high school students from different regions of Ethiopia learning the basics of programming and algorithms. Next summer the program will be held as well.

It was an amazing experience because I met a lot of cool and passionate students, teaching assistants and professors. As for TAs, we were working on problems for students, helping them with exercises, giving mini-lectures and had a lot of fun exploring Ethiopia together in our free time.

Students chosen for this program are good. They were selected by the Ministry of Education based on their achievements during studying in high school or applied themselves. Some students never used a computer before the program still being quite good at maths and it was exciting to see their advancement from that level to ability to write some simple algorithms. After the program, they have an opportunity to continue study in the best universities in the world.

One of the organizers of this program is Jelani Nelson. He is a computer science professor who used to compete a lot on TopCoder and now runs this program. Teaching assistants are chosen from all over the world and some of them are also part of the competitive programming community. So I want to inspire you to apply as Reyna did it this year for me.

The exact dates of the program are not chosen yet, but it will likely be the middle of July to middle of August, for 5 weeks. The foundation will cover the flight and the hotel. If you need you can also ask for a stipend.

Apply here: addiscoder.com/#apply

For more details or some photos you can check out addiscoder.com

Hello everybody! A new round is upcoming and I'm honored to be its author. The round will first appear as the onsite for Dasha.AI Code Championship and later we will hold a rated mirror. Everybody is welcomed to participate in Codeforces and I wish good luck for people in Saint Petersburg and Novosibirsk.

Using the opportunity, I want to thank:

• mnbvmar for helping in the preparation of a great part of everything. Really, without you, I wouldn't do it.
• 300iq for coordination and help with preparation.
• As always, MikeMirzayanov for taking care of international competitive programming and making such great platforms as Codeforces and Polygon.
• KAN, zscoder, Lewin, Jeffrey, Darkstalker, Darko and Gtaumaturgo for testing the problems and great advice.
• Dasha.Ai for an organization and a sponsorship.

Scoring will appear later.

Good luck and see you during the contest!

UPD1a: Scoring in div2: 500-750-1250-1750-2500-3000

UPD1b: Scoring in div1: 500-1000-1500-2250-(1500+1250)-3500

UPD2: editorial

UPD3: Congratulations to the winners!

In div1:

1. Um_nik
2. yosupo
3. ksun48

In div2:

1. lqs2o15
2. rainboy
3. HoshigakiKisame

In the onsite competition in Saint Petersburg:

1. aid
2. vintage_Vlad_Makeev
3. cookiedoth

In the onsite competition in Novosibirsk:

1. Timonnable
2. Pechalka
3. Maho

Hello.

It is not an official announcement of the events. Just information: The contest on Sep/22/2019 12:05 (Moscow time) will be only for onsite finalists. The mirror round will be the next day on Sep/23/2019 17:05 (Moscow time).

Hope to see many participants. Guess, who are the main writers of the Final?

Hello everyone! This round will be a little bit special because it is composed from the problemset of Saratov school elimination stage to the all-russian olympiad of school students. The problems were invented and prepared by Alexander fcspartakm Frolov, Ivan BledDest Androsov and me, Vladimir vovuh Petrov. Good luck to everyone!

UPD: Thanks to Daria nooinenoojno Stepanova and Danila sad101010 Smirnov for testing!

UPD2: We will open solutions to view and start the hacking phase a little bit later because the school elimination stage is not over yet. We will open all in about two hours. Please don't discuss any solutions during next two hours.

UPD3: Now you can discuss problems.

UPD4: Editorial is published!

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Hello! Codeforces Round 587 (Div. 3) will start at Sep/21/2019 10:05 (Moscow time). You will be offered 6 or 7 problems (or 8) 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 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. I tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 or 7 (or 8) problems and 2 hours 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 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.

Thanks to MikeMirzayanov for the platform, help with ideas for problems and for coordination of my work. Thanks to my good friends Mikhail awoo Piklyaev, Maksim Neon Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

I also would like to say that participants who will submit wrong solutions on purpose and hack them afterwards (example) will not be shown in the hacking leaders table.

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