[C++] 백준 2839번 : 설탕 배달

https://www.acmicpc.net/problem/2839

#include <iostream>

using namespace std;

int main() {

int in_kg, cnt = 0;

int kg5, kg3;

cin >> in_kg;

kg5 = (in_kg - in_kg % 5) / 5;

while (kg5 >= 0) {

if (((in_kg - kg5 * 5) % 3) == 0) {

kg3 = (in_kg - kg5 * 5) / 3;

cnt = kg5 + kg3;

kg5 = 0;

}

kg5--;

}

if (cnt == 0)

cout << "-1";

else

cout << cnt;

}