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Vovuh's blog

By Vovuh, history, 2 weeks ago, In English,

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?

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By Vovuh, history, 2 weeks ago, In English,

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>

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By Vovuh, history, 4 weeks ago, In English,

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

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By Vovuh, history, 4 weeks ago, translation, In English,

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>

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By Vovuh, history, 7 weeks ago, In English,

All ideas except the problem C belong to MikeMirzayanov.

1213A - Chips Moving

Tutorial
Solution

1213B - Bad Prices

Tutorial
Solution

1213C - Book Reading

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

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By Vovuh, history, 7 weeks ago, translation, In English,

<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!

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By Vovuh, history, 2 months ago, In English,

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

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By Vovuh, history, 2 months ago, translation, In English,

<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!

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By Vovuh, history, 3 months ago, In English,

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

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By Vovuh, history, 3 months ago, translation, In English,

<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

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By Vovuh, history, 3 months ago, In English,

1195A - Drinks Choosing

Idea: Nebuchadnezzar

Preparation: Nebuchadnezzar

Tutorial
Solution

1195B - Sport Mafia

Idea: ?

Preparation: MikeMirzayanov and _kun_

Tutorial
Solution (binary search)
Solution (formula)

1195C - Basketball Exercise

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

Idea: Nebuchadnezzar

Preparation: ima_ima_go

Tutorial
Solution

1195F - Geometers Anonymous Club

Idea: senek_k

Preparation: Nebuchadnezzar

Tutorial
Solution

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By Vovuh, history, 3 months ago, In English,

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!

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By Vovuh, history, 4 months ago, In English,

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

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By Vovuh, history, 4 months ago, In English,

<almost-copy-pasted-part>

Hello! Codeforces Round #570 (Div. 3) will start at Jun/26/2019 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 Ashishgup and kocko for help with round preparation and testing!

UPD2: The contest will be extended for 15 minutes because the problems are more interesting than we thought. We also advise to read all the problems because some of them may have the same difficulty and we cannot know which one will be easier for you than the other.

UPD3: Editorial is published!

UPD4:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 MbahFaishol1937 8 248
2 bertmin 8 450
3 BaiBatyr 8 455
4 LJF007 7 305
5 proizvedenie 7 322

Congratulations to the best hackers:

Rank Competitor Hack Count
1 Nazarbek_Baltabaev 120:-90
2 Radewoosh 75:-21
3 yzm10 36:-2
4 csegura 31
5 shaker007 30:-11
798 successful hacks and 492 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A blast 0:01
B Kirill_Kudr22 0:04
C I_love_HellHoleStudios 0:04
D divya_rawat 0:10
E llbra9z 0:13
F FlyInTheSky 0:42
G MbahFaishol1937 0:27
H UMP45 0:25

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By Vovuh, history, 4 months ago, In English,

1176A - Divide it!

Idea: Vovuh

Tutorial
Solution

1176B - Merge it!

Idea: MikeMirzayanov

Tutorial
Solution

1176C - Lose it!

Idea: Vovuh

Tutorial
Solution

1176D - Recover it!

Idea: MikeMirzayanov

Tutorial
Solution

1176E - Cover it!

Idea: MikeMirzayanov

Tutorial
Solution

1176F - Destroy it!

Idea: BledDest

Tutorial
Solution

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By Vovuh, history, 4 months ago, translation, In English,

<almost-copy-pasted-part>

Hello! Codeforces Round #565 (Div. 3) will start at Jun/09/2019 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. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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>

UPD1: Big thanks to Um_nik, Rudy358, nigus, opukittpceno_hhr and Temotoloraia for testing the round! And also big thanks to my dear friends Ivan BledDest Androsov, Roman Roms Glazov and Mikhail PikMike Piklyaev for help with round preparation!

UPD2: Editorial is published!

UPD3:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 Yushen 6 235
2 Violet_user 6 293
3 BudiArb 6 345
4 xenoframium 6 350
5 njchung93 6 439

Congratulations to the best hackers:

Rank Competitor Hack Count
1 nikolapesic2802 69:-15
2 stefdasca 42:-11
3 dorijanlendvaj 15:-11
4 orz_liuwei 10:-11
5 interestingLSY 5:-1
170 successful hacks and 236 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A riz_1_ 0:02
B _ekaterina_dudina 0:04
C BudiArb 0:05
D hxylalala 0:18
E csts.21 0:17
F njchung93 0:32

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By Vovuh, history, 5 months ago, In English,

1170A - Three Integers Again

Idea: Vovuh

Solution: elizarov

Tutorial
Solution

1170B - Bad Days

Idea: MikeMirzayanov

Solution: elizarov

Tutorial
Solution

1170C - Minus and Minus Give Plus

Idea: MikeMirzayanov

Solution: elizarov

Tutorial
Solution

1170D - Decoding of Integer Sequences

Idea: MikeMirzayanov

Solution: elizarov

Tutorial
Solution

1170E - Sliding Doors

Idea: adedalic

Solution: elizarov

Tutorial
Solution

1170F - Wheels

Idea: MikeMirzayanov, Vovuh, pashka

Solution: Benq

Tutorial
Solution

1170G - Graph Decomposition

Idea: MikeMirzayanov

Solution: elizarov

Tutorial
Solution

1170H - Longest Saw

Idea: MikeMirzayanov

Solution: pashka

Tutorial
Solution

1170I - Good Subsets

Idea: MikeMirzayanov

Solution: pashka

Tutorial
Solution

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By Vovuh, history, 5 months ago, In English,

1165A - Remainder

Idea: Vovuh

Tutorial
Solution

1165B - Polycarp Training

Idea: MikeMirzayanov

Tutorial
Solution

1165C - Good String

Idea: BledDest

Tutorial
Solution

1165D - Almost All Divisors

Idea: MikeMirzayanov

Tutorial
Solution

1165E - Two Arrays and Sum of Functions

Idea: Vovuh

Tutorial
Solution

1165F1 - Microtransactions (easy version)

Idea: BledDest

Tutorial
Solution

1165F2 - Microtransactions (hard version)

Idea: BledDest

Tutorial
Solution

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By Vovuh, history, 5 months ago, In English,

I have nothing to say this time, so meet yet another Div. 3 round :)

<almost-copy-pasted-part>

Hello! Codeforces Round #560 (Div. 3) will start at May/14/2019 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. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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 nhho, chenjb and ksun48 for testing the round.

UPD2: I also would like to thank my friend Adilbek adedalic Dalabaev for valuable suggestions about the contest and testing it!

UPD3: Editorial is published!

UPD4:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 nuoyanli 7 368
2 Vaseline_Warrior 7 437
3 adimiclaus15 7 446
4 1716638489 7 604
5 leo990629 6 335

Congratulations to the best hackers:

Rank Competitor Hack Count
1 Java 68:-2
2 figdan 63:-13
3 makjn10 44:-1
4 csts.21 40
5 yashi2552 27
872 successful hacks and 341 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A Tokisaki-Kurumi 0:03
B CoolAttacks 0:03
C igniubi 0:08
D foool 0:13
E maverick_10 0:15
F1 cunt 0:27
F2 cunt 0:26

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By Vovuh, history, 6 months ago, In English,

1157A - Reachable Numbers

Idea: BledDest

Tutorial
Solution

1157B - Long Number

Idea: BledDest

Tutorial
Solution

1157C1 - Increasing Subsequence (easy version)

Idea: MikeMirzayanov

Tutorial
Solution

1157C2 - Increasing Subsequence (hard version)

Idea: MikeMirzayanov

Tutorial
Solution

1157D - N Problems During K Days

Idea: MikeMirzayanov

Tutorial
Solution

1157E - Minimum Array

Idea: Vovuh

Tutorial
Solution

1157F - Maximum Balanced Circle

Idea: MikeMirzayanov

Tutorial
Solution

1157G - Inverse of Rows and Columns

Idea: Vovuh

This is the comment about the quadratic solution. Thank you so much for mentioning this fact, STommydx!

Tutorial
Solution

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By Vovuh, history, 6 months ago, translation, In English,

Suddenly, this round will consist of 7 different problems also!

UPD2: The round will consist of 7 problems and one of them will be in easy and hard editions!

<almost-copy-pasted-part>

Hello! Codeforces Round #555 (Div. 3) will start at Apr/26/2019 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. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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>

UPD0: I also would like to thank my friend Adilbek adedalic Dalabaev for helping me with understanding problems difficulty and other help with round preparation!

UPD1: Big thanks to dreamoon_love_AA, Ashishgup, jeel_vaishnav and lizi_lzy for testing the round!

UPD3: Editorial is published!

UPD4:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 FloodBenz 8 282
2 maguihong123 7 347
3 dreagonm 7 373
4 DeathYmz 7 571
5 BaiBatyr 6 189

Congratulations to the best hackers:

Rank Competitor Hack Count
1 WileE.Coyote 448:-33
2 Disappointment 127:-20
3 wzw19991105 39
4 ismagilov.code 50:-23
5 Kucha 20:-3
919 successful hacks and 365 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A ImAlsoChildish 0:01
B BaiBatyr 0:06
C1 darshit_99 0:10
C2 Injetzk 0:16
D iamnotacoder 0:21
E BaiBatyr 0:12
F Injetzk 0:29
G Injetzk 1:15

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By Vovuh, history, 6 months ago, In English,

1154A - Restoring Three Numbers

Idea: MikeMirzayanov

Tutorial
Solution

1154B - Make Them Equal

Idea: MikeMirzayanov

Tutorial
Solution

1154C - Gourmet Cat

Idea: le.mur

Tutorial
Solution

1154D - Walking Robot

Idea: MikeMirzayanov

Tutorial
Solution

1154E - Two Teams

Idea: MikeMirzayanov

Tutorial
Solution

1154F - Shovels Shop

Idea: MikeMirzayanov

Tutorial
Solution

1154G - Minimum Possible LCM

Idea: MikeMirzayanov

Tutorial
Solution

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By Vovuh, history, 6 months ago, translation, In English,

This time I have nothing to say except that this round will consist of 7 different problems!

<almost-copy-pasted-part>

Hello! Codeforces Round #552 (Div. 3) will start at Apr/16/2019 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. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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 le.mur for idea of one of the problems.

UPD2: Editorial is published now!

UPD3:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 ysluo2000 7 229
2 fake_delete_pls2 7 251
3 KefaKuma 6 178
4 Zhao-L 6 222
5 haimiaoyuzhao 6 240

Congratulations to the best hackers:

Rank Competitor Hack Count
1 wzw19991105 49:-4
2 ScreaMood 42:-1
3 I_love_Maria_Krylova 35:-5
4 Hacked_ 31:-1
5 Zombie358 30:-7
949 successful hacks and 502 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A MinatoYukina 0:01
B MinatoYukina 0:04
C Chess_fan 0:08
D nikizakr 0:07
E FluffyTT 0:21
F FluffyTT 0:09
G 1tst 0:14

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  • +200
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By Vovuh, history, 7 months ago, In English,

1144A - Diverse Strings

Idea: MikeMirzayanov

Tutorial
Solution

1144B - Parity Alternated Deletions

Idea: MikeMirzayanov

Tutorial
Solution

1144C - Two Shuffled Sequences

Idea: MikeMirzayanov

Tutorial
Solution

1144D - Equalize Them All

Idea: Vovuh

Tutorial
Solution

1144E - Median String

Idea: Vovuh

Tutorial
Solution

1144F - Graph Without Long Directed Paths

Idea: MikeMirzayanov

Tutorial
Solution

1144G - Two Merged Sequences

There is different solution for the problem, it is pretty interesting! Thanks, Roundgod!

Idea: Vovuh

Tutorial
Solution

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By Vovuh, 7 months ago, translation, In English,

Hello! Hope you missed me :) As far as some people say, because of copy-pasted announcement this round wouldn't be interesting. But the real thing is that I'm very sick now and I'm very glad that I prepared this round at all. Hope you will enjoy it. Good luck to all!

<copy-pasted-part>

Hello! Codeforces Round #550 (Div. 3) will start at Mar/31/2019 17:05 (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. Probably, participants from the first division will not be at all interested by this problems. And for 1600-1899 the problems will be too easy. 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.

</copy-pasted-part>

UPD: Editorial is published!

UPD2:

Congratulations to the winners:

Rank Competitor Problems Solved Penalty
1 WNSGB 7 206
2 kaixinqi 7 335
3 _sysjuruo 6 188
4 Moririn2528 6 206
5 CarusoX 6 212

Congratulations to the best hackers:

Rank Competitor Hack Count
1 wanderer163 21
2 tokitsukaze 14
3 nazarov.shohrukh 6
4 SMit_mangukiya 4
5 VikasChandak 4
93 successful hacks and 132 unsuccessful hacks were made in total!

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

Problem Competitor Penalty
A anurag918273 0:02
B probIem-solving 0:07
C ProPan_without_Pro 0:05
D vnquynh_hac_am 0:12
E probIem-solving 0:28
F sjcakioi 0:16
G izone 0:20

Read more »

 
 
 
 
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