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Stepavly's blog

By Stepavly, 11 months ago, translation, In English

Hello, Codeforces!

UPD: Since the round seems a little more complicated than usual after testing, we extended the round length by 15 minutes.

<almost-copy-pasted-part>

Hello! Codeforces Round #725 (Div. 3) will start at Jun/10/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended 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 7 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 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.

The problems for this round were invented by MikeMirzayanov, Supermagzzz and Stepavly.

Thanks to Fly_37, -is-this-fft-, A_Le_K, ALILILILILI-KHAN, ANZ, hocky, KazamaHoang, Sho, ASIXER, songsinger, OlegZubkov, AlexFetisov, darkkcyan, ivanzuki, kocko, Gassa for help with testing the round.

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

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UPD: Editorial

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By Stepavly, 12 months ago, translation, In English

Can somebody explain how to solve such problem: given values $$$x$$$, $$$L$$$, $$$R$$$, $$$M$$$ ($$$0 \le L \le R \le M - 1$$$), find minimal $$$k \ge 0$$$ such that $$$L \le (x \cdot k) \mod M \le R$$$.

This problem appeared in NEERC19 (Golf time) as a subtask, but the editorial not so clearly explains the algorithm for that subtask.

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By Stepavly, 13 months ago, translation, In English

Unfortunately, due to Internet provider network issues, we have to postpone the round. The current plan, that the round is postponed by 24 hours, will start on May/05/2021 17:35 (Moscow time).

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #719 (Div. 3) will start at May/05/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended 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 7 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 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.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and Aris.

Thanks to Gassa, BledDest, Programmer, bugdone, ruban, RedAnt, songsinger and Gornak40 for help with testing the round.

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

</almost-copy-pasted-part>

Editorial is ready!

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By Stepavly, 13 months ago, translation, In English

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #713 (Div. 3) will start at Apr/10/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended 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 7 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 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.

The problems for this round were invented by MikeMirzayanov, Supermagzzz, Stepavly and sodafago.

Thanks Gassa, darkkcyan, bfs.07, Tzak, songsinger, Mukundan314, iankury, drunya, sodafago, ChOmPs, Programmer, Khairy, IITianUG, Rox for helping with testing the round!

Thanks to MikeMirzayanov for platforms and coordination of our work. Good luck!

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Editorial: https://codeforces.com/blog/entry/89535

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By Stepavly, 14 months ago, translation, In English

1506A - Strange Table

Problem author: sodafago

Editorial
Solution

1506B - Partial Replacement

Problem author: MikeMirzayanov

Editorial
Solution

1506C - Double-ended Strings

Problem author: MikeMirzayanov

Editorial
Solution

1506D - Epic Transformation

Problem author: MikeMirzayanov

Editorial
Solution

1506E - Restoring the Permutation

Problem author: MikeMirzayanov

Editorial
Solution

1506F - Triangular Paths

Problem author: MikeMirzayanov, Stepavly, Supermagzzz

Editorial
Solution

1506G - Maximize the Remaining String

Problem author: MikeMirzayanov

Editorial
Solution

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By Stepavly, 15 months ago, translation, In English

1490A - Dense Array

Problem author: MikeMirzayanov

Editorial
Solution

1490B - Balanced Remainders

Problem author: MikeMirzayanov

Editorial
Solution

1490C - Sum of Cubes

Problem author: MikeMirzayanov

Editorial
Solution

1490D - Permutation Transformation

Problem author: MikeMirzayanov

Editorial
Solution

1490E - Accidental Victory

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1490F - Equalize the Array

Problem author: MikeMirzayanov

Editorial
Solution

1490G - Old Floppy Drive

Problem authors: Stepavly, Supermagzzz, MikeMirzayanov, sodafago

Editorial
Solution

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By Stepavly, 16 months ago, translation, In English

1475A - Odd Divisor

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1475B - New Year's Number

Problem author: MikeMirzayanov

Editorial
Solution

1475C - Ball in Berland

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1475D - Cleaning the Phone

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1475E - Advertising Agency

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1475F - Unusual Matrix

Problem authors: Stepavly, Supermagzzz

Editorial
Solution

1475G - Strange Beauty

Problem author: MikeMirzayanov

Editorial
Solution

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By Stepavly, history, 17 months ago, translation, In English

Happy New Year, Codeforces!

UPD: We have received such different opinions about the order of problems, that we cannot be completely sure about it. We recommend you to read all the problems and do not strongly hope that the difficulty for you necessarily coincides with the order in the round.

<almost-copy-pasted-part>

Hello! Codeforces Round #693 (Div. 3) will start at Jan/04/2021 17:35 (Moscow time). You will be offered 7 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. We tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 7 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 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.

The problems for this round were invented by MikeMirzayanov and prepared by Supermagzzz and Stepavly

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to darkkcyan, Aris, Mukundan314, PrideBlack, Nemo, pashka, Rox for help in round preparation and testing the round.

Good luck!

</almost-copy-pasted-part>

UPD: Editorial

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By Stepavly, 17 months ago, translation, In English

All problems were created by MikeMirzayanov and developed by me (Stepavly) and Supermagzzz.

1462A - Favorite Sequence

Editorial
Solution

1462B - Last Year's Substring

Editorial
Solution

1462C - Unique Number

Editorial
Solution

1462D - Add to Neighbour and Remove

Problem authors: MikeMirzayanov, Supermagzzz, Stepavly.

Editorial
Solution

1462E1 - Close Tuples (easy version)

Editorial
Solution

1462E2 - Close Tuples (hard version)

Editorial
Solution

1462F - The Treasure of The Segments

Editorial
Solution

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By Stepavly, history, 23 months ago, translation, In English

Hello, Codeforces!

<almost-copy-pasted-part>

Hello! Codeforces Round #650 (Div. 3) will start at Jun/16/2020 17:35 (Moscow time). You will be offered 6 problems (one of them will have subtasks) 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 1600 or higher, can register for the round unofficially. The round will be hosted by rules of educational rounds (extended ACM-ICPC). Thus, during the round, solutions will be judged on preliminary tests, and after the round it will be a 12-hour phase of open hacks. We tried to make strong tests — just like you will be upset if many solutions fail after the contest is over.

You will be given 6 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 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.

The problems for this round were invented by MikeMirzayanov, me and Supermagzzz and prepared by me and Supermagzzz.

Thanks to MikeMirzayanov for platforms and coordination of our work. Thanks to harlequen, manta1130, lynmisakura, Gassa, Rox, antontrygubO_o, armoking, JustasLe, iankury, Sho, bugdone, Khairy for help in round preparation and testing the round.

Good luck!

Editorial

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By Stepavly, 2 years ago, translation, In English

All problems were invented by MikeMirzayanov and developed by me, Stepavly, and Supermagzzz.

1360A - Minimal Square

Editorial
Solution

1360B - Honest Coach

Editorial
Solution

1360C - Similar Pairs

Editorial
Solution

1360D - Buying Shovels

Editorial
Solution

1360E - Polygon

Editorial
Solution

1360F - Spy-string

Editorial
Solution

1360G - A/B Matrix

Editorial
Solution

1360H - Binary Median

Editorial
Solution

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By Stepavly, history, 2 years ago, translation, In English

1282A - Temporarily unavailable

Idea: MikeMirzayanov Preparation: MikeMirzayanov

Editorial
Solution (MikeMirzayanov)

1282B1 - K for the Price of One (Easy Version), 1282B2 - K for the Price of One (Hard Version)

Idea: MikeMirzayanov, unreal.eugene Preparation: Supermagzzz

Editorial
Solution (Supermagzzz)

1282C - Petya and Exam

Idea: AdvancerMan Preparation: Supermagzzz

Editorial
Solution (Supermagzzz)

1282D - Enchanted Artifact

Idea: unreal.eugene Preparation: unreal.eugene

Editorial
Solution (Darui99)

1282E - The Cake Is a Lie

Idea: MikeMirzayanov, AdvancerMan Preparation: AdvancerMan

Editorial
Solution (AdvancerMan)

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