Leetcode 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. 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.

Solution 1: Simple math

 public 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;  
   }  
 }