大数阶乘算法

#include<stdio.h>
int main()
{
int a[8000], an, n, i, f;
for(; scanf("%d", &n) != EOF; puts(""))
{
for(i = 0; i < 8000; a[i++] = 0);
for(a[0] = an = 1; n; n--, f ? (a[an++] = f) : 0)
for(f = i = 0; i < an; i++)
{
a[i] = a[i] * n + f;
f = a[i] / 100000;
a[i] %= 100000;
}
for(printf("%d", a[--an]); an--; printf("%05d", a[an]));
}
return 0;
}