Longest Palindrome Substring

Problem Statement

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

Leetcode link

Example 1:

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

Example 2:

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

Constraints:

• 1 <= s.length <= 1000
• s consist of only digits and English letters.

Code

Python Code

class Solution:
    def longestPalindrome(self, s: str) -> str:
        longest = ''
        def findLongest(s, l, r):
            while l>=0 and r<len(s) and s[l] == s[r]:
                l-=1
                r+=1
            return s[l+1:r]

        for i in range(len(s)):
            s1 = findLongest(s, i, i)
            if len(s1) > len(longest): longest = s1

            s2 = findLongest(s, i, i+1)
            if len(s2) > len(longest): longest = s2

        return longest