main.cpp

#include <iostream>

class Solution
{
public:
    bool isPalindrome(int x)
    {
        // Special cases:
        // As discussed above, when x < 0, x is not a palindrome.
        // Also if the last digit of the number is 0, in order to be a palindrome,
        // the first digit of the number also needs to be 0.
        // Only 0 satisfy this property.
        if (x < 0 || (x % 10 == 0 && x != 0))
        {
            return false;
        }

        int revertedNumber = 0;
        while (x > revertedNumber)
        {
            revertedNumber = revertedNumber * 10 + x % 10;
            x /= 10;
        }

        // When the length is an odd number, we can get rid of the middle digit by revertedNumber/10
        // For example when the input is 12321, at the end of the while loop we get x = 12, revertedNumber = 123,
        // since the middle digit doesn't matter in palidrome(it will always equal to itself), we can simply get rid of it.
        return x == revertedNumber || x == revertedNumber / 10;
    }
};

int main()
{
    Solution model;
    bool v = model.isPalindrome(1265621);
    std::cout << v << std::endl;
}