Palindrome Number

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

分析：把一个数倒过来，然后看两个数是否相同。

 public class Solution {
     public boolean isPalindrome(int x) {
         if (x < ) {
             return false;
         }
         long palindromeX = , inputX = x;
         while (x > ) {
             palindromeX = palindromeX *  + (x % );
             x = x / ;
         }
         return palindromeX == inputX;
     }
 }

Reverse digits of an integer.

Example1: x = 123, return 321
Example2: x = -123, return -321

Note:
Assume we are dealing with an environment which could only store integers within the 32-bit signed integer range: [−231,  231 − 1]. For the purpose of this problem, assume that your function returns 0 when the reversed integer overflows.

 public class Solution {
     public int reverse(int x) {
         boolean isPositive = true;

         if (x < ) {
             x = -x;
             isPositive = false;
         }

         long reversedValue = ;
         while (x != ) {
             reversedValue = reversedValue *  + x % ;
             x /= ;
         }
         if (Math.abs(reversedValue) > Integer.MAX_VALUE) return ; 

         return isPositive ?  (int)reversedValue : (int)(-reversedValue);
     }
 }