LeetCode OJ：Ugly Number（丑数）

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.

 

丑数的计算，分别去除数字中的2，3，5部分，如果数字被整除了那么就是丑数，否则不是，下见代码：

 1 class Solution {
 2 public:
 3     bool isUgly(int num) {
 4         if(num == 0)
 5             return false;
 6         while(num % 2 == 0) num /= 2;//exclude 2 factor
 7         while(num % 3 == 0) num /= 3;//exclude 3 factor
 8         while(num % 5 == 0) num /= 5;//exclude 5 factor
 9         return (num == 1);//is Ugly
10     }
11 };

 java版本如下所示，方法相同：

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

 

posted @ 2015-10-07 10:56  eversliver  阅读(225)  评论(0)  编辑  收藏  举报