Palindrome Number

问题描述

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

Some hints:

Could negative integers be palindromes? (ie, -1)

If you are thinking of converting the integer to string, note the restriction of using extra space.

You could also try reversing an integer. However, if you have solved the problem "Reverse Integer", you know that the reversed integer might overflow. How would you handle such case?

算法

代码一

1 public boolean isPalindrome(int x){
2         int rev=0;
3         int x1=x;
4         while(x>0){
5             rev=rev*10+x%10;
6             x/=10;
7         }
8         return x1==rev;
9     }

代码二

 1 public boolean isPalindrome(int x){
 2         if(x<0)
 3             return false;
 4         String s=Integer.toString(x);
 5         int l=s.length();
 6         for(int i=0;i<=(l/2);i++){
 7             if(s.charAt(i)!=s.charAt(l-i-1)){
 8                 return false;
 9             }
10         }
11         return true;
12     }

注意事项：

1.注意代码一与Reverse Integer的差别。