263. Ugly Number

题目

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, 8 are ugly while14 is not ugly since it includes another prime factor7.

Note that 1 is typically treated as an ugly number.

我的解法

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

算法分析：若是脏数，则不断除2、除3、除5，最后一定得到1；否则就不是。