leetcode 172. Factorial Trailing Zeroes

Seawolf

Given an integer n, return the number of trailing zeroes in n!.

Example 1:

Input: 3
Output: 0
Explanation: 3! = 6, no trailing zero.
Example 2:

Input: 5
Output: 1
Explanation: 5! = 120, one trailing zero.
Note: Your solution should be in logarithmic time complexity.

解题思路：1个5对应1个0，25对应2个0，125对应3个0，依次类推....

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