263.Ugly Number

@target 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

思路：

这里丑数一定是由2，3，5因子组成，那么逐一尝试对2，3，5取余，若余数为0，则含有某一因子。若均不含有，那一定不是丑数。

	public boolean isUgly(int num) {        if(num <= 0){        	return false;        }        int num2 = num % 2;        int num3 = num % 3;        int num5 = num % 5;        while(num2 == 0||num3 == 0||num5 == 0){        	if(num2 == 0){        		num = num / 2;        	}        	else if(num3 == 0){        		num = num / 3;        	}        	else {        		num = num / 5;        	}        	num2 = num % 2;        	num3 = num % 3;        	num5 = num % 5;        }        return num == 1;    }