Palindrome Number (LeetCode Math)

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

Idea: First keep a copy of the original value. Then reverse x by repeating dividing x by 10 and using a collector to keep adding the corresponding values. The compare the collector with the original value of x, if equals, return true, otherwise false.

Time: O(lgn) Space: O(1), where n is the value of x.

Code:

 public class Solution {  
   public boolean isPalindrome(int x) {  
     if(x<0)  
       return false;  
     int ori=x;  
     int sum=0;  
     while(x>0)  
     {  
       sum=sum*10+x%10;  
       x=x/10;  
     }  
     return ori==sum;  
   }  
 }