263. Ugly Number

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.

分析：
如果输入为0，则不是丑数。因为第一个丑数是1
先除以2，除到余数不为0
再除以3，除到余数不为0
最后除以5，最后的余数如果为1，则为丑数

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)? true:false;    }};