大数据之大数阶乘

描述
我们都知道如何计算一个数的阶乘，可是，如果这个数很大呢，我们该如何去计算它并输出它？
输入
输入一个整数m(0

50

样例输出

30414093201713378043612608166064768844377641568960512000000000000

代码如下

import java.util.Scanner;

/** * Created by lcc on 2017/5/26. */
public class dashuju {
    public static void main(String[] args)
    {

        Scanner input = new Scanner(System.in);
        int[] cal = new int[10010];
        int num = input.nextInt();
        cal[0] = 1;
        for(int index = 1; index <= num; ++index )
        {
            for(int i = 0; i < 10000; i++)
            {
                cal[i] = cal[i]*index;

            }
            for(int i = 0; i < 10000; i++)
            {
                cal[i+4] = cal[i+4]+ cal[i]/10000;
                cal[i+3] = cal[i+3]+ cal[i]%10000/1000;
                cal[i+2] = cal[i+2]+ cal[i]%1000/100;
                cal[i+1] = cal[i+1]+ cal[i]%100/10;
                cal[i+0] = cal[i]%10;


            }
        }


        int x = 10000;
        while(cal[x] == 0)
            x--;
        for(int i2 = x; i2 >= 0; i2--)
        {
            System.out.print(cal[i2]);
        }
        System.out.println();



    }


}

参考

http://www.voidcn.com/article/p-esdfqnco-zc.html