[leetcode] Ugly Number

题目：

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.

思路：不断除以2，不断除以3，不断除以5，最后如果结果为1，则是ugly number。

Java代码：

    public boolean isUgly(int num) {
        if(num <= 0) {
            return false;
        }
        int[] primes = {2, 3, 5};
        for(int p : primes) {
            while(num % p == 0) {
                num /= p;
            }
        }
        return num == 1;
    }