class Solution:
    def longestPalindrome(self, s: str) -> str:

        if len(s) == 0:
            return ""

        is_palindrome = [[False for _ in range(len(s))] for _ in range(len(s))]
        longest_palindrome = s[0]

        for i in range(len(s)):
            is_palindrome[i][i] = True
            if i < len(s) - 1 and s[i] == s[i + 1]:
                is_palindrome[i][i + 1] = True
                longest_palindrome = s[i:i + 2]

        for length in range(2, len(s)):
            for st in range(len(s) - length):
                if is_palindrome[st + 1][st + length - 1] and s[st] == s[st + length]:
                    is_palindrome[st][st + length] = True
                    longest_palindrome = s[st:st + length + 1]

        return longest_palindrome