LeetCode 172. Factorial Trailing Zeroes

Description

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

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

Example 1:

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

Example 2:

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

Note: Your solution should be in logarithmic time complexity.

Explanation

one 5 one zero

Python Solution

class Solution:
    def trailingZeroes(self, n: int) -> int:

        product = 1
        zero_count = 0

        while n > 1:
            zero_count += n // 5;
            n //= 5

        return zero_count
  • Time complexity: ~N
  • Space complexity: ~1

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