(백준 2839) DP

www.acmicpc.net/problem/2839

2839번: 설탕 배달

#include <stdio.h>
int main(void)
{
    int num, cnt5, cnt3 = 0;
    scanf("%d", &num);
    cnt5 = num / 5;
    if (num % 5)
    {
        for (cnt5; cnt5 > 0; cnt5--)
            if ((num - 5 * cnt5) % 3 == 0)
            {
                cnt3 = (num - 5 * cnt5) / 3;
                break;
            }
        if (cnt5 == 0 && num % 3 == 0)cnt3 = num/3;
    }
    if (!(cnt5 + cnt3))printf("-1");
    else printf("%d", cnt5 + cnt3);
    return 0;
}