9. Palindrome Number

https://leetcode.com/problems/palindrome-number/

1. Revert half of the number

//12 ms    5.9 MB
class Solution {
public:
    bool isPalindrome(int x) {
        if(x < 0)
            return false;
        if(x == 0)
            return true;   
        //x > 0
        long long int curr = 0; //we have a test case 2147483647, over the limit of int
        long long int orig = x; //so apply long long int
        while(x != 0){
            curr = curr * 10 + (x % 10);
            x /= 10;
        }
        if(curr != orig)
           return false;
        else
           return true;
    }
};

Time complexity:
Space complexity: O(1)