Ugly Number whose prime factors only include 2, 3, 5. For example, 6, 8 are ugly while 14 is not

最新推荐文章于 2020-10-22 01:40:47 发布

最新推荐文章于 2020-10-22 01:40:47 发布 · 831 阅读

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本文介绍了一种检查给定数字是否为丑数的有效算法。丑数定义为仅包含2、3、5这三个质因数的正整数。文中提供了Java代码实现，并通过循环去除这些质因数来判断一个数是否符合丑数的标准。

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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.

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

public class Solution {
public boolean isUgly(int num) {
        while (num >= 2) {
            if (num % 2 == 0) num /= 2;
            else if (num % 3 == 0) num /= 3;
            else if (num % 5 == 0) num /= 5;
            else return false;
        }
        return num == 1;   //这个判断好巧妙啊，涵盖了我上边的num<1的情况
    }
}