Solution.cpp

class Solution
{
public:
    std::string longestPalindrome(std::string s)
    {
        if (s.length() <= 1)
        {
            return s;
        }

        int max_len = 1;
        std::string max_str = s.substr(0, 1);

        for (int i = 0; i < s.length(); ++i)
        {
            for (int j = i + max_len; j <= s.length(); ++j)
            {
                if (j - i > max_len && isPalindrome(s.substr(i, j - i)))
                {
                    max_len = j - i;
                    max_str = s.substr(i, j - i);
                }
            }
        }

        return max_str;
    }

private:
    bool isPalindrome(const std::string &str)
    {
        int left = 0;
        int right = str.length() - 1;

        while (left < right)
        {
            if (str[left] != str[right])
            {
                return false;
            }
            ++left;
            --right;
        }

        return true;
    }
};