9. Palindrome Number

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

跟第七题有很大的相似，回文数的规律就是反转后跟之前一样，所以直接拿来。

class Solution {
    public boolean isPalindrome(int x) {
       int result = 0;
        int y = x;
        if (x < 0) {
            return false;
        }
        while (true) {
            int n = y % 10;
            result = result * 10 + n;
            if (result % 10 != n) {
                return false;
            }
            y = (y - n) / 10;
            if (y == 0) {
                break;
            }
        }
        return x == result;
    }
}