Leetcode 263. Ugly Number

263. Ugly Number

• Total Accepted: 65061
• Total Submissions:173755
• Difficulty: Easy

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.

思路：按定义做。

代码：

 1 class Solution {
 2 public:
 3     bool isUgly(int num) {
 4         if(num<=0){
 5             return false;
 6         }
 7         while(num%2==0){
 8             num=num>>1;
 9         }
10         while(num%3==0){
11             num/=3;
12         }
13         while(num%5==0){
14             num/=5;
15         }
16         return num==1;
17     }
18 };