#9 Palindrome Number

问题：

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?
There is a more generic way of solving this problem.

代码：

package solution;

public class Solution9 {
    public static boolean isPalindrome(int x) {
        if(x<0 || (x!=0 && x%10 == 0))
            return false;
        int rev = 0;
        while (x>rev){
            rev = rev*10 + x%10;
            x = x/10;
        }
        return (x == rev || x == rev/10);
        //x == rev是偶数位数字时情况，而x == rev/10是奇数位数字时的情况
    }
    public static void main(String[] args){
        int a = 12321;
        int b = 123321;
        int c = 123456;
        System.out.println(isPalindrome(a));
        System.out.println(isPalindrome(b));
        System.out.println(isPalindrome(c));
    }
}