Problem: Ugly Number

Question

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:

1 is typically treated as an ugly number.
Input is within the 32-bit signed integer range.

Solution

TODO

Code

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

        return true;
    }
}

Performance