Write a PRogram to check whether a given number is an ugly number.

Ugly numbers are positive numbers whose prime factors only include2, 3, 5. For example,6, 8are ugly while14is not ugly since it includes another prime factor7.

Note that1is typically treated as an ugly number.

這是今天才加上去的新題。沒啥可說的。只要把ugly number的定義搞清楚就可以很好的寫了。

因為prime factor只能為2，3，5。所以只要一個數(shù)不能被分解為只含有這三個數(shù)的乘式那么它就不是一個ugly number了。

代碼如下。~

public class Solution {    public boolean isUgly(int num) {        if(num<=0){            return false;        }        if(num==1){            return true;        }        while(num!=1){            if(num%2==0){                num=num/2;            }else if(num%3==0){                num=num/3;            }else if(num%5==0){                num=num/5;            }else{                return false;            }        }        return true;    }}