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By Supermagzzz, history, 3 days ago, translation, In English

1538A - Stone Game

Author: MikeMirzayanov

Tutorial
Solution

1538B - Friends and Candies

Author: MikeMirzayanov

Tutorial
Solution

1538C - Number of Pairs

Author: MikeMirzayanov

Tutorial
Solution

1538D - Another Problem About Dividing Numbers

Author: MikeMirzayanov

Tutorial
Solution

1538E - Funny Substrings

Author: MikeMirzayanov

Tutorial
Solution

1538F - Interesting Function

Author: Supermagzzz, Stepavly

Tutorial
Solution

1538G - Gift Set

Author: MikeMirzayanov

Tutorial
Solution

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By maroonrk, history, 2 days ago, In English

We will hold Tokio Marine & Nichido Fire Insurance Programming Contest 2021(AtCoder Regular Contest 122).

The point values will be 400-500-600-700-800-1200.

We are looking forward to your participation!

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By kashyapriya754, 2 days ago, In English

****I request the cheaters to please somehow let me know the rating of their real father whose code they copy , so that i can make a target to surpass him and won’t have to be bothered by such dumbfucks again?

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By gavy_pole, history, 2 days ago, In English

For the Codeforces Round #725 (Div. 3), check these two submissions: 119070732 and 119073742. These two codes are 99% similar. My question is how come these same submissions (template aside) didn't get skipped? MikeMirzayanov, please look into this.
Anyway, these guys are new type of cheaters. They cheat by exchanging codes and this is not the first time. For further proof, check these two as well: 119047376 and 119057342 (the function is same and only variables are changed). They have plagiarized in Codechef contests as well (obviously) but that's another story for another time.
So would you like to explain your actions, lordgavy01 and south_pole? What do you gain from this?


Update: I just came to know that these two guys, instead of accepting their mistake, are telling their friends to downvote this blog as much as possible. I don't understand this behaviour. Just accept your mistake and move on.

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By chokudai, history, 17 hours ago, In English

We will hold AtCoder Beginner Contest 205.

The point values will be 100-200-300-400-500-600.

We are looking forward to your participation!

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By Dormi, history, 88 minutes ago, In English

1534A - Colour the Flag

Author: crackersamdjam

Hint 1
Hint 2
Hint 3
Tutorial
Solution

1534B - Histogram Ugliness

Author: Dormi

Hint 1
Hint 2
Hint 3
Tutorial
Solution

1534C - Little Alawn's Puzzle

Author: Ninjaclasher

Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Solution

1534D - Lost Tree

Author: Plasmatic

Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Solution

1534E - Lost Array

Author: Plasmatic

Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Solution

1534F1 - Falling Sand (Easy Version)

Author: Dormi

Hint 1
Hint 2
Hint 3
Hint 4
Tutorial
Solution

1534F2 - Falling Sand (Hard Version)

Author: Dormi

Hint 1
Hint 2
Hint 3
Hint 4
Hint 5
Tutorial
Solution

1534G - A New Beginning

Author: Aaeria

Tutorial
Solution

1534H - Lost Nodes

Author: Ninjaclasher

Tutorial
Solution

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By maroonrk, history, 11 hours ago, In English

After the last ARC, one participant pointed out that the result is WA when the error is precisely the same as $$$EPS$$$ (submission).

For example, consider these two outputs: 331997010.50000000000000000000 (the jury output) and 331997342.4970105 (the user output). Their relative error is exactly $$$10^{-6}$$$, so when $$$EPS=10^{-6}$$$, this should get AC.

However, with the current implementation of the doubleCompare function in testlib.h, the result is WA. This is because perturbations in the line 429 (return result + 1E-15 >= minv && result <= maxv + 1E-15;) don't work when the values of result/minv/maxv are large. We made a fix and sent a pull request.

If you believe you were affected by this in the last ARC, please let me know.

That being said, given the popularity of testlib.h and the fact that no one has ever raised this issue, I hope no one was affected by this in the entire history of testlib.h.

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By MohamedAboOkail, history, 7 hours ago, In English

Hello everyone!

This (What is Codeforces?) is the first blog post on Codeforces, 11 years ago by MikeMirzayanov

I wanted to thank MikeMirzayanov for this great website, which has become an integral part of our daily lives!

Also, thank you to all the Codeforces community!

I have a lot of Beautiful memories with Codeforces in the past two years.

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By rahul_107, 13 hours ago, In English
### Question:
There is a grid with a balloon at some cells. Players can shoot arrows from outside the grid horizontally and vertically. Every arrow shot will burst all balloons in that row if fired horizontally and in that column if fired vertically.
Given the positions of the balloons in the grid find the minimum no of arrows required to burst all the balloons.

### Constraints:
1 <= N(No of ballons) <= 50
0 <= x, y -> Positions of the balloons < 10^9-1

### Input Format:
Line1: Integer denoting N.
Next N lines, where each of the ith lines contains two integers representing (row, col) of ith balloon.

### Sample Input :
6
15 21
33 8
17 21
17 8
28 11
28 19

### Sample Output:
3

### Sample Input :
6
15 1
15 2
15 3
15 4
18 1
20 1

### Sample Output:
2

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By gabrielwu, history, 26 hours ago, In English

Thank you to everyone who participated in the mBIT Spring 2021 competition today! All of the information on this blog post is also available in our archive, which includes the full leaderboard.

Problems and Editorials

Test your solutions on our Codeforces Gyms: Standard, Advanced

Results

First, we would like to congratulate the team Texas (Adam Bertelli, Dilhan Salgado, Zack Lee) for being the first team to find all of the Among Us references hidden in the problems! Without further ado, we are pleased to announce the division winners:

Advanced Division

Winning Teams:

  1. KoreshaMaksim Gorokhovskii, Ramazan Rakhmatullin

  2. jharada fan clubHuaiyu Wu, Antonio Molina, Yuting Zhou, Maryam Bahrani

  3. ඞYTN3M (HS team) — Elliot En-Yi Liu (National Experimental High School at Hsinchu Science Park), Ashley Aragorn Khoo (NUS High School), Udit Sanghi (Bhavan Vidyalaya), Panchkula Kostiantyn Savchuk (Lyceum No. 2 of Korostyshiv)

  4. ScrubsRaymond Kang, Li Yao'an, Koh Li Chen

  5. we can fill this out later but I have to put something to save (HS team) — Moses Xu (Appleby College), Eric Pei (Don Mills CI), Chris Trevisan (William Lyon Mackenzie CI), Victor Gao (Victoria Park CI)

  6. Coast (HS team) — Anand John (Brandywine High School), Nathan Chen (Garnet Valley High School), Richard Qi (Princeton High School), Siyong Huang (Homestead High School)

Standard Division

Winning HS Team: Remdi™Nishchay Bhutoria (Nehru Smarka Vidyalaya), Vishesh Saraswat (DPS RK Puram), Aryan Raina (Sri Guru Harkrishan Model School), Ritul Kumar Singh (DPS Bokaro Steel City)

First Place MS Team: The Purple DuckDaniel Wu (Tilden MS), Paul Trusov (Tilden MS), David Sy (Tilden MS)

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