9. Palindrome Number

Determine whether an integer is a palindrome. Do this without extra space.

判断一个数是不是回文数

C++(182ms):

 1 class Solution {
 2 public:
 3     bool isPalindrome(int x) {
 4         if(x < 0 || (x != 0 && x%10 == 0))
 5             return false ;
 6         int sum = 0 ;
 7         while(x > sum){
 8             sum = sum*10 + x%10 ;
 9             x /= 10 ;
10         }
11         return (x == sum) || (x == sum/10) ;
12     }
13 };

Java(188ms):

 1 class Solution {
 2     public boolean isPalindrome(int x) {
 3         if(x < 0 || (x != 0 && x%10 == 0))
 4             return false ;
 5         int sum = 0 ;
 6         while(x > sum){
 7             sum = sum*10 + x%10 ;
 8             x /= 10 ;
 9         }
10         return (x == sum) || (x == sum/10) ;
11     }
12 }