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263. Ugly Number

Difficulty Topics

Description

An ugly number is a positive integer whose prime factors are limited to 2, 3, and 5.

Given an integer n, return true if n is an ugly number.

 

Example 1:

Input: n = 6
Output: true
Explanation: 6 = 2 × 3

Example 2:

Input: n = 1
Output: true
Explanation: 1 has no prime factors, therefore all of its prime factors are limited to 2, 3, and 5.

Example 3:

Input: n = 14
Output: false
Explanation: 14 is not ugly since it includes the prime factor 7.

 

Constraints:

  • -231 <= n <= 231 - 1

Solution

ugly-number.py
class Solution:
    def isUgly(self, n: int) -> bool:
        if n <= 0: return False

        while n % 5 == 0: n //= 5
        while n % 3 == 0: n //= 3
        while n % 2 == 0: n //= 2

        return n == 1