263. Ugly Number（丑数）

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.

    public boolean isUgly(int num) {
        if(num<1) return false;
        if(num==1) return true;

        while(num%2==0) num=num/2;     
        while(num%3==0) num=num/3;    
        while(num%5==0) num=num/5;

        return num==1;
    }