leetcode-java-263. Ugly Number

最新推荐文章于 2021-04-10 08:43:34 发布

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本文介绍了一种用于检查给定数字是否为丑数的算法。丑数定义为仅包含2、3、5这三个质因数的正整数。文章通过逐步除以2、3、5来简化输入数字，直至不能被这些数字整除为止。

/*
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 <= 0) {
             return false;
         }
         if(num == 1) {
             return true;
         }
         while(num % 2 == 0 && num >=2) {
             num = num/2;
         }
         while(num % 3 == 0 && num >=3) {
             num = num/3;
         }
         while(num % 5 == 0 && num >=5) {
             num = num/5;
         }
         return num == 1;
     }
 }