263-ugly-number

Question

https://leetcode.com/problems/ugly-number/description/

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. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

Example:

Thought Process

1. Divide All Factors
   1. While we can divide an factor perfectly, we divide
   2. At the end, we compare the final num to 1

Solution

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

Additional