5. Longest Palindromic Substring

class Solution:
    def longestPalindrome(self, s: str) -> str:
        max_ss = {}
        
        if s == "":
            return ""
        elif len(s) == 1:
            return s
        else:
            for i in range(0, len(s)):
                for j in range(i + 1, len(s) + 1):
                    ss = s[i:j]
                    if ss == ss[::-1]:
                        max_ss[len(ss)] = ss
                        
            return max_ss[max(max_ss.keys())]