Leetcode 172 Factorial Trailing Zeroes

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

Note: Your solution should be in logarithmic time complexity.

Credits:
Special thanks to @ts for adding this problem and creating all test cases.

题目解析：

这道题是问n!的结果后面有几个0的, 可以转化成n!里面有几个5的 (注意25, 125..这种都是5的平方啊立方啊这种要注意一下)

public int trailingZeroes(int n) {
        if(n <= 0)
            return 0;
        int num = 0;
        while(n != 0){
            n = n / 5;
            num += n;
        }
        return num; 
}