[LeetCode] Palindrome Number

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

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0)   return false;
        string a = "";
        while(x)
        {
            a += x % 10 + '0';
            x /= 10;
        }
        string b(a);
        reverse(a.begin(), a.end());
        return a == b;
    }
};