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.

Credits:

Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.
思路：除以2，3，5直到不能除为止，最后应该是1，要为其他数，则不是ugly number.

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