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.
这道题让我们检测一个数是否为丑陋数，所谓丑陋数就是其质数因子只能是2,3,5。那么最直接的办法就是不停的除以这些质数，如果剩余的数字是1的话就是丑陋数了，有两种写法，如下所示：
解法一：
class Solution { public: bool isUgly(int num) { while (num >= 2) { if (num % 2 == 0) num /= 2; else if (num % 3 == 0) num /= 3; else if (num % 5 == 0) num /= 5; else return false; } return num == 1; } };
解法二：
class Solution { public: bool isUgly(int num) { if (num <= 0) return false; while (num % 2 == 0) num /= 2; while (num % 3 == 0) num /= 3; while (num % 5 == 0) num /= 5; return num == 1; } };
本文转自博客园Grandyang的博客，原文链接：丑陋数[LeetCode] Ugly Number ，如需转载请自行联系原博主。
