LeetCode 0172 - Factorial Trailing Zeroes

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

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

class Solution {
public:
    long long trailingZeroes(long long n) {
        long long res = 0;
        for(long long i = 5; n / i; i *= 5)
            res += n / i;
        return res;
    }
};