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 that 1 is typically treated as an ugly number.

EXPLANATION:

就是不断的除以这三个数，但是有可能会有timelimit问题出来。

SOLUTION:

public boolean isUgly(int num) {
        for (int i=2; i<6 && num>0; i++)
            while (num % i == 0)
                num /= i;
            return num == 1;
    }