172. Factorial Trailing Zeros

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

Problem

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

Follow up: Could you write a solution that works in logarithmic time complexity?

Example 1:

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

Example 2:

Input: n = 5
Output: 1
Explanation: 5! = 120, one trailing zero.

Example 3:

Input: n = 0
Output: 0

Constraints:

• 1 <= n <= 104

Solution

class Solution {
public:
    int trailingZeroes(int n) {
        if (n < 5) return 0;
        int count = 0;
        for (int i = 5; i <= n; i *= 5) {
            count += n / i;
        }
        return count;
    }
};

• #math