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.

题目解答：这个题目用来判断当前的这个给定num是否是丑数，丑数的规则已经给定：（1）正整数；（2）素数因子只有2,3,5；（3）1也是丑数之一。

代码如下：

class Solution {

public:

    bool isUgly(int num) {

        if(num <= 0)

            return false;

        if(num == 1)

            return true;

        while(num % 2 == 0)

        {

            num /= 2;

        }

        while(num % 3 == 0)

        {

            num /= 3;

        }

        while(num % 5 == 0)

        {

            num /= 5;

        }

        if(num == 1)

        {

            return true;

        }

        return false;

    }

};