LeetCode [172] Factorial Trailing Zeroes

Note:

• method1: #5 = #trailing zeros
•                ...5...10...15...20...25...30...125...625
• #5              1     1     1     1    2     1      3       4       

 
Ref
[1] https://oj.leetcode.com/problems/factorial-trailing-zeroes/
OJ
[2] https://oj.leetcode.com/discuss/20691/my-explanation-of-the-log-n-solution
method1