Problem

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

Example

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

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

Code

static int var = [](){
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();
class Solution {
public:
    int trailingZeroes(int n) {
        int res = 0;
        while(n>=5){
            n = n / 5;
            res += n;
        }
        return res;
    }
};

Result

172. Factorial Trailing Zeroes.png