HDU 2069 Coin Change

#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e5 + 10;
int a[1111][1111];
int b[6]= {1, 5, 10, 25, 50};

int main()
{
    int n;
    while(~scanf("%d", &n))
    {
        memset(a, 0, sizeof(a));
        a[0][0]=1;
        for(int j = 0; j <= 4; j ++)
        {
            for(int i = b[j]; i <= n; i ++)
            {
                for(int k = 1;k <= 100; k++)
                {
                    if(i >= b[j])
                        a[k][i] += a[k-1][i - b[j]];
                }
            }
        }
        int sum = 0;
        for(int i = 0; i <= 100; i ++)
        {
            sum += a[i][n];
        }
        printf("%d\n",sum);
    }
    return 0;
}