肯定是大叔，本来以为用加法做乘法，后来想想这样麻烦，还是可以使用乘法的，按位乘，ov可以看成不止一位，程序如下所示：
#include <stdio.h>
#define MAX 40000
int main() {
unsigned int res[MAX];
int n;
int ov, i, j, k;
int pos;
while (scanf("%d", &n) != EOF) {
res[] = ;
pos = ;
for (i=; i<=n; i++) {
ov = ;
for (j=; j<pos; j++) {
k = res[j] * i + ov;
res[j] = k%;
ov = k / ;
}
while (ov) {
res[pos++] = ov % ;
ov /= ;
}
}
for (i=pos-; i>=; i--)
printf("%d", res[i]);
printf("\n");
}
return ;
}