# 263. Ugly Number

Write a program to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include 2, 3, 5.

Example 1:

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

Example 2:

Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2

Example 3:

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

Note:

  1. 1 is typically treated as an ugly number.
  2. Input is within the 32-bit signed integer range: [−2^31, 2^31 − 1].

# Solution

Approach 1: Check if the number can only be divided by 2, 3, 5.

# Code (Python)

Approach 1:

    def isUgly(self, num: int) -> bool:
        if num <= 0:
            return False
        uglies = [2, 3, 5]
        for ugly in uglies:
            while num % ugly == 0:
                num = num / ugly
        return num == 1

# Code (C++)

Approach 1:

class Solution {
public:
    bool isUgly(int num) {
        if (num == 0) return false;
        while (num % 2 == 0) num = num / 2;
        while (num % 3 == 0) num = num / 3;
        while (num % 5 == 0) num = num / 5;
        return num == 1;
    }
};