263. Ugly Number

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.

判断一个数是不是丑数

C++（3ms）：

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

java(2ms):

 1 class Solution {
 2     public boolean isUgly(int num) {
 3         if (num == 0)
 4             return false ;
 5         while(num%2==0) num/=2 ;
 6         while(num%3==0) num/=3 ;
 7         while(num%5==0) num/=5 ;
 8         return num == 1 ;
 9     }
10 }