UVA 357 Let Me Count The Ways

UVA_357

    用dp进行计数即可，状态转移方程为f[i,j]=Sum{f[i][j-k*a[i]]}(j-k*a[i]>=0,k为整数)，其中i代表第i种面值，j代表当前有j的cents，a[i]为第i种面值的大小。

#include<stdio.h>
#include<string.h>
#define MAXD 30010
int d[] = {1, 5, 10, 25, 50};
long long int f[10][MAXD];
void prepare()
{
    int i, j, k;
    memset(f, 0, sizeof(f));
    for(i = 0; i < MAXD; i ++)
        f[0][i] = 1;
    for(i = 1; i < 5; i ++)
        for(j = 0; j < MAXD; j ++)
            for(k = 0; k * d[i] <= j; k ++)
                f[i][j] += f[i - 1][j - k * d[i]];
}
int main()
{
    int k, n;
    prepare();
    while(scanf("%d", &n) == 1)
    {
        if(f[4][n] == 1)
            printf("There is only 1 way to produce %d cents change.\n", n);
        else
            printf("There are %lld ways to produce %d cents change.\n", f[4][n], n);
    }
    return 0;
}