McDic's blog

By McDic, history, 5 days ago, In English,

Sorry for such difficulty balance. Here is the editorial.

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Solution Code for A

Behind story of B: Original B was harder. None of 2100+ rated testers solved original B, so it got downgraded. Also there was more than 15 pretests before.

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Solution Code for B

Behind story of C: C is created before few days to contest. If there was no current C, the contest would have hell balances.

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Solution Code for C

Behind story of D: Honestly I predicted D as hell hard problem. But other high rated people said it's not that hard.

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Solution Code for D

Behind story of E: I didn't expected such well-known problem. My solution for E is more complicated.

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Solution Code for E

Behind story of F: This problem was located at D originally.

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Solution Code for F

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By McDic, history, 6 days ago, In English,

안녕하세요, 코드포스! (Hello, Codeforces!)

I'm super happy to introduce you to Codeforces Round #566 (Div. 2), which will take place on Jun/11/2019 16:05 (Moscow time).

The round will be rated for all Division 2 participants, yet any Division 1 participants are welcome to join us out of competition.

You will be given 6 problems and 2 hours to solve them. Score distribution will be announced later.

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

This is my first Codeforces contest ever. I hope everyone who will join this contest enjoy. Thank you!

WINNERS:

  1. Castor
  2. thecodinglizard
  3. puyu_liao
  4. UoA_Kanade
  5. It5t
  6. LucaSeri
  7. orz_liuwei
  8. emengdeath
  9. ashutosh450
  10. hyfzbtrs

UPDATES:

  1. Let me spread the meme from McDic Minecraft Telegram group — Ggungah.
  2. Score distribution is 500-750-1250-2000-2250-2750.
  3. Editorial is available.
  4. Congratulations for the winners!
  5. I am sorry for weak systests for B and F. Sorry again.

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By McDic, 7 weeks ago, In English,

Recently I made a problem that requires calculating 20~30 digits of precision. (Calculating high precision is not a main idea, it's just required to solve this problem easily. This approach can be avoided and solvable by only big integers, but it needs very unusual mathematical observation.)

One of my friends said this problem should not be opened for Competitive Programming participants. He said this problem is bad because this requires hard work to self-implement high precision data structures or use built-in structures are not in C++ like Python's decimal.Decimal or Java's java.math.BigDecimal.

Why this feature makes this problem bad as competitive programming problem? I can see many problems in Codeforces force users to use either fast languages like C++ or very weird usage of system calls like I/O operations. Also, some data structures like Red-Black tree are not built in some languages like Python 3. Why not for this case?

Can anyone explain? Thanks in advance.

I removed that problem from my current proposal list. If I succeed to deal with constraints to make avoid BigDecimal/BigInteger easily, I will add it. Other problems are not forcing you to use such data structures. Thank you for all feedbacks.

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

Hello.

I am wondering why Codeforces uses separated problems for subtask instead of separated test cases. Polygon is already supporting to have multiple testsets to act similar as subtasks, also Checker from testlib.h supports _pc (Partially Correct), which is intended to give partial score. So I think there is no reason to make separated problems such like R542 Div1 A1. It will be better if Codeforces just give participants partial score instead. Anyone have opinion about it?

Thanks for reading this.

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

Hello.

Just started to participate contests to fill 25 participation in codeforces, now I even created my github repository to store my implementation :)

The link is here: https://github.com/McDic/MyImplementations/

Just wanted to show public, you can freely see or criticize my code anytime.

Thank you for reading this.

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By McDic, 5 months ago, In English,

I don't even know if my message is reached to Codeforces coordinator correctly. If there is a spreadsheet or document(Google spreadsheet might be the good choice.) to show current Codeforces Round Proposal queue status, people can check if their message is arrived correctly and estimate their email's response time. I hope they will make it someday.

Added 1: It seems GlebsHP is offline for almost 2 months and I sent the proposal email to him. Are he still one of the contributors? If not which coordinator should I resend my proposal email?

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By McDic, 5 months ago, In English,

Hello. I am using Polygon to prepare problems.

This is my generator below:

#include <iostream>
#include "testlib.h"

long long int max2(long long int a, long long int b){
	return a>b ? a : b;
}

long long int ten(int x){
	long long int s=1;
	for(int i=0; i<x; i++) s *= 10;
	return s;
}

int main(int argc, char* argv[]){
	registerGen(argc, argv, 1);
	
	std::cout << rnd.next(1LL, atoll(argv[1])) << " ";
	std::cout << rnd.next(1LL, atoll(argv[2])) << " ";
	std::cout << rnd.next(1LL, atoll(argv[3])) << " ";
	std::cout << rnd.next(max2(1, atoll(argv[4])/10), max2(100, atoll(argv[4]))) << std::endl;
}

Is there any wrong thing? It always verdict FL in invocation and tests. Thank you for reading this.

EDIT 1 This is the log occurs when I try to generate inputs. ERROR: Unexpected verdict Can't prepare input file 'C:\Contesters\Work\invoker-prod\work\polygon2\34b2efc622c48530be13ce1989b01907\check-bc2d7412ca16433314f5a03914c1d409\run\input.fd0138e687.txt'.FAILED. Input:

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