AtCoder Beginner Contest 161 C Replacing Integer formula derivation

AtCoder Beginner Contest 161 The   number of contestants is 9927   fast, see all questions 5 minutes after the start of the contest

AtCoder Beginner Contest 161 C Replacing Integer formula derivation

See https://blog.csdn.net/mrcrack/article/details/104454762 for the general catalog

Online evaluation address https://atcoder.jp/contests/abc161/tasks/abc161_c

Manual simulation example

7 4

1

|7-4|=3
|3-4|=1
|1-4|=3
|3-4|=1


2 6

2

|2-6|=4
|4-6|=2
|2-6|=4
|4-6|=2

Confirmed by the above simulation, the minimum value is found in the difference operation of n% k, k. First n% = k , then n <k

|n-k|=k-n,

|k-n-k|=n,

|n-k|=k-n,

|k-n-k|=n

Therefore, the answer only needs to find the minimum value in n, kn .

AC code is as follows

#include <stdio.h>
#define LL long long
int main(){
	LL n,k;
	scanf("%lld%lld",&n,&k);
	n%=k;
	if(n>k-n)printf("%lld\n",k-n);
	else printf("%lld\n",n);
}