Ugly Number LeetCode Solution | Easy Approach

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Ugly Number An ugly number is a positive integer whose prime factors are limited to 23, 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

Ugly Number Solutions

Time: O(log n)
Space: O(1)

C++

class Solution {
 public:
  bool isUgly(int n) {
    if (n == 0)
      return false;

    for (const int prime : {2, 3, 5})
      while (n % prime == 0)
        n /= prime;

    return n == 1;
  }
};

Java

 class Solution {
  public boolean isUgly(int n) {
    if (n == 0)
      return false;

    for (final int prime : new int[] {2, 3, 5})
      while (n % prime == 0)
        n /= prime;

    return n == 1;
  }
}

 

Python


class Solution:
  def isUgly(self, n: int) -> bool:
    if n == 0:
      return False

    for prime in 2, 3, 5:
      while n % prime == 0:
        n //= prime

    return n == 1

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