hdu1042 N!

题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=1042

N!

Time Limit: 10000/5000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 58278    Accepted Submission(s): 16547

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

 

题目大意：求N!        比如求123!我们肯定是要1*2*3*.....*123；如果直接这样做下去，毋庸置疑的会超时，那么我们就要将他一位一位存下来。一位一位的乘过去。做过的东西，还要想好久，还是不扎实，一定要多动脑。

 

详见代码。

 1 #include <iostream> 2 #include <cstdio> 3 #include <cstring> 4  5 using namespace std; 6 int num[80000]; 7 int main () 8 { 9     int n,pre;10     while (~scanf("%d",&n))11     {12         memset(num,0,sizeof(num));13         num[0]=1;14         int len=1;15         for (int i=2; i<=n; i++)16         {17             pre=0;18             for (int j=0; j<len; j++)19             {20                 num[j]=num[j]*i+pre/10;21                 pre=num[j];22                 num[j]=num[j]%10;23             }24             while (pre>9)25             {26                 num[len]=pre/10%10;27                 len++;28                 pre/=10;29             }30         }31         for (int i=len-1; i>=0; i--)32             printf ("%d",num[i]);33         printf ("\n");34     }35     return 0;36 }