Palindrome Number

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

Analyse：判断一个整数是否是回文数。注意负数都不是回文数。

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0) return false;
        string s;
        while(x){
            char temp = x % 10 + '0';
            s += temp;
            x /= 10;
        }
        bool result = true;
        for(int i = 0; i < s.length() / 2; i++){
            if(s[i] != s[s.length() - 1 - i]) return false;
        }
        return true;
    }
};

 或者：

class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0) return false;
        else if(x < 10) return true;
        else{
            int div = 1000000000;
            while(x / div == 0) div /= 10;
            bool result = true;
            while(x){
                int left = x / div;
                int right = x % 10;
                if(left != right){
                    result = false;
                    break;
                }
                x = (x- left * div) / 10;
                div /= 100;
            }
            return result;
        }
    }
};