Trailing Zeros

Write an algorithm which computes the number of trailing zeros in n factorial.

Have you met this question in a real interview? 

Yes

Example

11! = 39916800, so the out should be 2

Challenge

O(log N) time

class Solution {
    /*
     * param n: As desciption
     * return: An integer, denote the number of trailing zeros in n!
     */
    public long trailingZeros(long n) {
        // write your code here
        if(n <= 0) return 0;
        long count = 0;
        for(long i = 5; n / i >= 1; i*=5){
            count += n / i;
        }
        return count;
    }
};