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, 8are ugly while14is not ugly since it includes another prime factor7.
Note that
1is typically treated as an ugly number.
丑数就是分解因子之后只含有2,3,5的数就是丑数，题目是判断一个整数是不是丑数，简单到只有这一种解法，没有别的了
My Solution
(Java) Version 1 Time: 2ms:
判断性质先跟着定义走，既然丑数是又2,3,5相乘得来的，那就除回去，先是用2除，除到除不尽了，就用3除，再用5除，如果是丑数的话，那肯定最后会得到1，那这就是丑数
public class Solution {
public boolean isUgly(int num) {
if(num==1||num==2||num==3||num==5)return true;
if(num==0)return false;
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;
}
}
