求N的阶乘，超大数怎么做

Question

Problem Description
Given an integer N(0 ≤ N ≤ 10000), your task is to calculate N!

如n=10000,求N！

Answer 1

采用万进制，逢万进一，结果存于a数组，结果倒序输出，每个a[i]不足四位前面补0

#include <bits/stdc++.h>
using namespace std;
void f(int n){
    int a[10000+1]={1},carry,digits=1;
    for(int i=2;i<=n;i++){
        carry=0;
        for(int j=0;j<digits;j++){
            a[j]=a[j]*i+carry;
            carry=a[j]/10000;   //进位
            a[j]=a[j]%10000;  //余数
        }
        if(carry>0)
            a[digits++]=carry;
    }
    printf("%d",a[digits-1]);
    for(int j=digits-2;j>=0;j--)
        printf("%04d",a[j]);
    printf("\n");
}

int main(){
    int n;
    while(scanf("%d",&n)!=EOF){
        f(n);
    }
    return 0;
}