[Lintcode]Ugly Number

Write a program to check whether a given number is an uglynumber`.

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.

注意负数和零即可。

public class Solution {
    /**
     * @param num an integer
     * @return true if num is an ugly number or false
     */
    public boolean isUgly(int num) {
        if(num <= 0) return false;
        while(num > 0) {
            if(num % 2 == 0) num = num / 2;
            else if(num % 3 == 0) num = num / 3;
            else if(num % 5 == 0) num = num / 5;
            else if(num == 1) return true;
            else return false;
        }
        return true;
    }
}