"""
5. Longest Palindromic Substring
Medium

Given a string s, return the longest palindromic substring in s.

 

Example 1:

Input: s = "babad"
Output: "bab"
Note: "aba" is also a valid answer.

Example 2:

Input: s = "cbbd"
Output: "bb"

Example 3:

Input: s = "a"
Output: "a"

Example 4:

Input: s = "ac"
Output: "a"

 

Constraints:

    1 <= s.length <= 1000
    s consist of only digits and English letters (lower-case and/or upper-case),

"""
class Solution:
    def longestPalindrome(self, s: str) -> str:
        
        res = ''
        n = len(s)
        def chk(l,r):
            while l>= 0 and r < n and s[l] == s[r]:
                l -= 1
                r += 1
            return s[l+1:r]
        
        for i in range(n):
            res = max(chk(i,i), chk(i,i+1), res, key=len)
        
        return res
