[C++] 백준 2909번 : 캔디 구매

https://www.acmicpc.net/problem/2909

#include <iostream>

#include <math.h>

using namespace std;

int main() {

int n,k;

cin >> n >> k;

int tmp = pow(10,k);

int n1;

n1 = n % tmp;

n1 >= pow(10, k) / 2 ? n = n+(pow(10, k)-n1) : n = n - n1;

cout << n;

}