172 Factorial Trailing Zeroes

来源：Leetcode

原帖：https://leetcode.com/problems/factorial-trailing-zeroes/

题目：
Given an integer n, return the number of trailing zeroes in n!.
Note: Your solution should be in logarithmic time complexity.

代码：

 class Solution {  
 public:  
   int trailingZeroes(int n) {  
     if (n < 0) return 0;  
     int res = 0;  
     while (n) {  
       n /= 5;  
       res += n;  
     }  
     return res;  
   }  
 };