#Leetcode# 172. Factorial Trailing Zeroes

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

 

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.

代码：

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

　　找到这个数字里面 $5$ 的个数就可以  学到了