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### vovuh's blog

By vovuh, history, 3 weeks ago, ,

1296A - Array with Odd Sum

Idea: vovuh

Tutorial
Solution

Idea: vovuh

Tutorial
Solution

1296C - Yet Another Walking Robot

Idea: MikeMirzayanov

Tutorial
Solution

1296D - Fight with Monsters

Inspiration: 300iq, idea: vovuh

Tutorial
Solution

1296E1 - String Coloring (easy version)

Idea: MikeMirzayanov

Tutorial
Solution (dp)
Solution (greedy)

1296E2 - String Coloring (hard version)

Idea: MikeMirzayanov

Tutorial
Solution

1296F - Berland Beauty

Idea: MikeMirzayanov

Tutorial
Solution

• +97

By vovuh, history, 3 weeks ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #617 (Div. 3) will start at Feb/04/2020 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 Daria ZeroAmbition Stepanova, Mikhail pikmike Piklyaev, Maksim Ne0n25 Mescheryakov and Ivan BledDest Androsov for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial is published!

• +183

By vovuh, history, 4 weeks ago, ,

Thanks to Rox and _overrated_ for help with problem ideas and preparation!

1294A - Collecting Coins

Idea: MikeMirzayanov

Tutorial
Solution

1294B - Collecting Packages

Idea: MikeMirzayanov

Tutorial
Solution

1294C - Product of Three Numbers

Idea: MikeMirzayanov

Tutorial
Solution

1294D - MEX maximizing

Idea: Vovuh

Tutorial
Solution

1294E - Obtain a Permutation

Idea: Vovuh

Tutorial
Solution

1294F - Three Paths on a Tree

Idea: MikeMirzayanov

Tutorial
Solution

• +80

By vovuh, history, 5 weeks ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #615 (Div. 3) will start at Jan/22/2020 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 Daria ZeroAmbition Stepanova, Mikhail pikmike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

This is unusual, but good news! Our friends at Harbour.Space have a message for you:

Hi Codeforces!

As a special prize for the Codeforces Round #615, we would like to invite the top 3 participants to take part in our Hello Muscat ICPC Programming Bootcamp, which will take place in Oman, from March 19 to March 25, 2020. The prize will cover the participation fee, accommodation, and half-board meals for the entire duration of the bootcamp (except flights)!

There are three requirements to satisfy:

• You took part in at least 10 rated contests on Codeforces
• Your max rating should be less than 1900
• You should be eligible for ICPC and/or IOI 2020+
Fill out the form→

So unofficial participants are also in a game (if meet the requirements).

Good luck to everyone!

UPD: I want to thank Artem Rox Plotkin and Dmitrii _overrated_ Umnov for invaluable help with the round preparation!

UPD2: Editorial is published!

• +220

By vovuh, history, 2 months ago, ,

All problems were proposed by Mikhail MikeMirzayanov Mirzayanov.

1283A - Minutes Before the New Year

Tutorial
Solution

1283B - Candies Division

Tutorial
Solution

Tutorial
Solution

1283D - Christmas Trees

Tutorial
Solution

1283E - New Year Parties

Tutorial
Solution

1283F - DIY Garland

Tutorial
Solution

• +51

By vovuh, history, 2 months ago, translation, ,

Pay attention to the unusual round start time.

UPD: We cannot determine difficulty of some problems thus we recommend you to read all problems and think about each of them.

<almost-copy-pasted-part>

Hello! Codeforces Round #611 (Div. 3) will start at Dec/28/2019 20:05 (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 Daria ZeroAmbition Stepanova, Mikhail pikmike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

UPD2: Editorial is available!

• +152

By vovuh, history, 2 months ago, ,

All ideas except the problem C belong to MikeMirzayanov. The author of C is Rox.

Special thanks to opukittpceno_hhr for the invaluable help with the round preparation!

1272A - Three Friends

Tutorial
Solution

1272B - Snow Walking Robot

Tutorial
Solution

1272C - Yet Another Broken Keyboard

Tutorial
Solution

1272D - Remove One Element

Tutorial
Solution

1272E - Nearest Opposite Parity

Tutorial
Solution

1272F - Two Bracket Sequences

Tutorial
Solution

• +61

By vovuh, history, 2 months ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #605 (Div. 3) will start at Dec/12/2019 16:35 (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 Daria ZeroAmbition Stepanova, Mikhail PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

UPD: Great thanks to Artem rox Plotkin and Dmitrii opukittpceno_hhr Umnov for testing the round and help with bugs fixing! Artem is also proposed one of the problems for today's round!

UPD: Editorial is published!

• +166

By vovuh, history, 4 months ago, ,

1256A - Payment Without Change

Idea: MikeMirzayanov

Tutorial
Solution

1256B - Minimize the Permutation

Idea: Vovuh

Tutorial
Solution

1256C - Platforms Jumping

Idea: MikeMirzayanov

Tutorial
Solution

1256D - Binary String Minimizing

Idea: MikeMirzayanov

Tutorial
Solution

1256E - Yet Another Division Into Teams

Idea: MikeMirzayanov

Tutorial
Solution

1256F - Equalizing Two Strings

Idea: Vovuh

Tutorial
Solution

• +41

By vovuh, history, 4 months ago, translation, ,

UPD: The editorial is published!

<almost-copy-pasted-part>

Hello! Codeforces Round #598 (Div. 3) will start at Nov/04/2019 16:15 (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 Daria ZeroAmbition Stepanova, Mikhail PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

• +157

By vovuh, history, 4 months ago, ,

All ideas belong to MikeMirzayanov.

1249A - Yet Another Dividing into Teams

Tutorial
Solution

1249B1 - Books Exchange (easy version)

Tutorial
Solution

1249B2 - Books Exchange (hard version)

Tutorial
Solution

1249C1 - Good Numbers (easy version)

Tutorial
Solution

1249C2 - Good Numbers (hard version)

Tutorial
Solution

1249D1 - Too Many Segments (easy version)

Tutorial
Solution

1249D2 - Too Many Segments (hard version)

Tutorial
Solution

1249E - By Elevator or Stairs?

Tutorial
Solution

1249F - Maximum Weight Subset

Thanks to neal for the additional editorial of this problem and providing the linear solution!

Tutorial
Solution (Vovuh, n^3)
Solution (PikMike, n^2)

• +95

By vovuh, history, 4 months ago, translation, ,

UPD: Thanks to Daria ZeroAmbition Stepanova, Mikhail PikMike Piklyaev and Artem Rox Plotkin for help with round preparation!

UPD2: Editorial is published!

<almost-copy-pasted-part>

Hello! Codeforces Round #595 (Div. 3) will start at Oct/22/2019 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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

• +283

By vovuh, history, 5 months ago, ,

Suddenly, all problems expect A and D were invented by me. The author of A and D is MikeMirzayanov.

1234A - Equalize Prices Again

Tutorial
Solution

1234B1 - Social Network (easy version)

Tutorial
Solution

1234B2 - Social Network (hard version)

Tutorial
Solution

1234C - Pipes

Tutorial
Solution

1234D - Distinct Characters Queries

Tutorial
Solution

1234E - Special Permutations

Tutorial
Solution

1234F - Yet Another Substring Reverse

Tutorial
Solution
WA?

• +112

By vovuh, history, 5 months ago, ,

UPD: Special thanks to Mikhail PikMike Piklyaev for help with translation and problems discussing, Maksim Ne0n25 Mescheryakov for problems discussing, Artem Rox Plotkin, Daria ZeroAmbition Stepanova and Tommy STommydx Li for testing the round!

UPD2: Editorial is published!

<almost-copy-pasted-part>

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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

• +282

By vovuh, history, 5 months ago, ,

All problems except the problem F are invented by fcspartakm. The problem F idea belongs to BledDest.

1216A - Prefixes

Tutorial
Solution

1216B - Shooting

Tutorial
Solution

1216C - White Sheet

Tutorial
Solution 1
Solution 2

1216D - Swords

Tutorial
Solution

1216E1 - Numerical Sequence (easy version)

Tutorial
Solution

1216E2 - Numerical Sequence (hard version)

Tutorial
Solution

1216F - Wi-Fi

Tutorial
Solution

• +74

By vovuh, history, 5 months ago, translation, ,

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 ZeroAmbition 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!

<almost-copy-pasted-part>

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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

• +112

By vovuh, history, 6 months ago, ,

All ideas except the problem C belong to MikeMirzayanov.

1213A - Chips Moving

Tutorial
Solution

Tutorial
Solution

Tutorial
Solution

1213D1 - Equalizing by Division (easy version)

Tutorial
Solution

1213D2 - Equalizing by Division (hard version)

Tutorial
Solution

1213E - Two Small Strings

Tutorial
Solution

1213F - Unstable String Sort

Tutorial
Solution

1213G - Path Queries

Tutorial
Solution

• +105

By vovuh, history, 6 months ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #582 (Div. 3) will start at Aug/30/2019 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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

UPD: Thanks to Artem Rox Plotkin for testing the round!

UPD2: Editorial is published!

• +187

By vovuh, history, 6 months ago, ,

All ideas belong to MikeMirzayanov

1203A - Circle of Students

Tutorial
Solution

1203B - Equal Rectangles

Tutorial
Solution

1203C - Common Divisors

Tutorial
Solution

1203D1 - Remove the Substring (easy version)

Tutorial
Solution

1203D2 - Remove the Substring (hard version)

Tutorial
Solution

1203E - Boxers

Tutorial
Solution

1203F1 - Complete the Projects (easy version)

Tutorial
Solution

1203F2 - Complete the Projects (hard version)

Tutorial
Solution

Tutorial of W7 novice contest

• +57

By vovuh, history, 6 months ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #579 (Div. 3) will start at Aug/13/2019 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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

UPD: Editorial is published!

• +139

By vovuh, history, 7 months ago, ,

1196A - Three Piles of Candies

Idea: MikeMirzayanov

Tutorial
Solution

1196B - Odd Sum Segments

Idea: Vovuh

Tutorial
Solution

1196C - Robot Breakout

Idea: MikeMirzayanov and Vovuh

Tutorial
Solution

1196D1 - RGB Substring (easy version)

Idea: MikeMirzayanov

Tutorial
Solution

1196D2 - RGB Substring (hard version)

Idea: MikeMirzayanov

Tutorial
Solution

1196E - Connected Component on a Chessboard

Idea: MikeMirzayanov

Tutorial
Solution

1196F - K-th Path

Tutorial
Solution

• +42

By vovuh, history, 7 months ago, translation, ,

<almost-copy-pasted-part>

Hello! Codeforces Round #575 (Div. 3) will start at Jul/24/2019 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 PikMike Piklyaev, Maksim Ne0n25 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.

</almost-copy-pasted-part>

UPD: I also would like to thank Ivan BledDest Androsov for help with problems preparation, and also danya.smelskiy, greencis, chenjb and STommydx for testing the round!

UPD2: Editorial is published!

UPD3: I also would like to thank my friend Maksim Ne0n25 Mescheryakov for improving tests of the problem F! :D

• +144

By vovuh, history, 7 months ago, ,

1195A - Drinks Choosing

Tutorial
Solution

1195B - Sport Mafia

Idea: ?

Preparation: MikeMirzayanov and _kun_

Tutorial
Solution (binary search)
Solution (formula)

Idea: meshanya

Preparation: TsarN

Tutorial
Solution

1195D1 - Submarine in the Rybinsk Sea (easy edition)

Idea: MikeMirzayanov

Preparation: MikeMirzayanov

Tutorial
Solution

1195D2 - Submarine in the Rybinsk Sea (hard edition)

Idea: meshanya

Preparation: sava-cska

Tutorial
Solution

1195E - OpenStreetMap

Preparation: ima_ima_go

Tutorial
Solution

1195F - Geometers Anonymous Club

Idea: senek_k

Tutorial
Solution

• +30

By vovuh, history, 7 months ago, ,

Hi everyone! I'm glad to invite all of you to participate in Codeforces Round #574 (Div. 2) which will take a place in Jul/17/2019 17:35 (Moscow time).

This round is based on SIS team contest. You will be given 6 problems and 2 hours to solve them. This round will be rated for Div. 2 participants. In other words, this round will be rated for the participants with rating lower than 2100. As usual, participants from the first division are welcome to join out of competition.

Problems was invented and prepared by Nebuchadnezzar, Kurpilyansky, meshanya, TsarN, sava-cska, ima_ima_go and senek_k. I am just a coordinator of this round, I made a small amount of work such as English translations and editorials. I want to thank Mikhail MikeMirzayanov Mirzayanov for amazing systems Codeforces and Polygon, all authors of this great contest, KAN and _kun_ for help with difficulties estimating and choosing the problems and my dear friend Ivan BledDest Androsov for help with round preparation!

Good luck everyone and see only green system testing messages! :)

UPD: The scoring is 500 — 1000 — 1500 — (1000+1500) — 3000 — 3500.

UPD2: I would like to thank testers galloska, NatInTheHat and AlexPop28 for help and advices about the round!

UPD3: Editorial is published!

• +269

By vovuh, history, 8 months ago, ,

1183A - Nearest Interesting Number

Idea: MikeMirzayanov

Tutorial
Solution

1183B - Equalize Prices

Idea: MikeMirzayanov

Tutorial
Solution

1183C - Computer Game

Idea: MikeMirzayanov and Vovuh and BledDest

Tutorial
Solution

1183D - Candy Box (easy version)

Idea: MikeMirzayanov

Tutorial
Solution

1183E - Subsequences (easy version)

Idea: MikeMirzayanov

Tutorial
Solution

1183F - Topforces Strikes Back

Idea: Vovuh

Tutorial
Solution

1183G - Candy Box (hard version)

Idea: MikeMirzayanov

Tutorial
Solution

1183H - Subsequences (hard version)

Idea: MikeMirzayanov

Tutorial
Solution