C++ 大数阶乘求取--数组实现代码

1. 大数阶乘理论

http://blog.csdn.net/yxnk/article/details/1665052

2. 大数阶乘实现

http://hi.baidu.com/urzalknsyzchrur/item/3934e84e821b7de31381da8d

#include <iostream>
#include <cstdlib>
#include <string>
#include <stdio.h>

using namespace std;

int main(int argc, char *argv[])
{
	int n = 0;
	cout << "Please input the number for Factorial operate : ";
	cin  >> n;

	int LargeNumberFactorial[10000] = {0};
	LargeNumberFactorial[0]    = 1;        // 0! = 1 
	LargeNumberFactorial[1]    = 1;        // 第一位对应的数值初始为 1    
	int          digit         = 1;        // n!阶乘求取的位数初始为 1 

	for (int i = 1; i <= n; i++)           // 1,2,3,...,n
	{
		for (int j = 1; j <= digit; j++)
		{
			LargeNumberFactorial[j] *= i;  
		}
		
		for (int j = 1; j <= digit; j++)
		{
			if (LargeNumberFactorial[j] > 10)
			{
				for (int r = 1; r <= digit; r++)
				{
					if (LargeNumberFactorial[digit] > 9)
					{
						digit++;
					}
					LargeNumberFactorial[r+1] += LargeNumberFactorial[r]/10;
					LargeNumberFactorial[r]   %= 10;
				}
			}
		}
	}

	cout << n << "!= ";
	for (int k = digit; k > 0; k--)
	{
		cout << LargeNumberFactorial[k];
	}
	cout << endl;

	return 0;
}