HDU1042--N!

N!

Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 52040    Accepted Submission(s): 14673

Problem Description

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

 

Input

One N in one line, process to the end of file.

 

Output

For each N, output N! in one line.

 

Sample Input

1
2
3

 

Sample Output

1
2
6

 

解析：用数组模拟大数乘法，这里需要注意的是数组要开的大点，如果提交后wa，将自己的数组放大，看能否ac，除了这个其他应该没什么问题了哈！

贴一下自己的代码

#include<iostream>
#include <string.h>
const int MAXN = 40000;
int result[MAXN];
int main()
{
#ifdef LOCAL
	freopen("input.txt" , "r" , stdin);
	freopen("output.txt" , "w" , stdout);
#endif
	int n;
	while(std::cin >> n)
	{
		if(n == 0)
		{
			std::cout << 1 << std::endl;
		}else{
			memset(result , 0 , sizeof result );
			result[0] = 1;
			for(int i=1;i<=n;++i)
			{
				int c=0;
				//c为进位，模拟乘法运算
				for(int j=0; j<MAXN ;++j)
				{
					int temp=result[j]*i + c;
					c = temp/10;
					result[j] = temp%10;
				}
			}
			//标记出哪个位是最开始的位
			int flag;
			for(int i=MAXN-1; i>=0;--i)
			{
				if(result[i] != 0)
				{
					flag = i;
					break;
				}
			}
			for(int i=flag; i>=0; --i)
				std::cout << result[i];
			std::cout << std::endl;
		}	
	}
}