poj水题-1579 将递归记录会变快

#include <stdio.h>
long s[21][21][21] = {0};
int w(int a,int b,int c)
{
    if (a <= 0 || b <= 0 || c <= 0)
        return s[0][0][0]=1;

    if (a > 20 || b > 20 || c > 20)
        return w(20, 20, 20);
    if(s[a][b][c])return s[a][b][c];

    if (a < b && b < c)
        return s[a][b][c]=w(a, b, c-1) + w(a, b-1, c-1) - w(a, b-1, c);

return s[a][b][c]=w(a-1, b, c) + w(a-1, b-1, c) + w(a-1, b, c-1) - w(a-1, b-1, c-1);
}

int main()
{
    int a,b,c;
    while(1)
    {
        scanf("%d%d%d",&a,&b,&c);

        if(a==-1&&a==b&&a==c)
            break;
        printf("w(%d, %d, %d) = %d\n",a,b,c,w(a,b,c));
    }




return 0;
}