Longest palindromic substring

class Solution:
    def solve(self, s, left, right):
        while left >= 0 and right < len(s) and s[left] == s[right]:
            left -= 1
            right += 1
        return s[left+1:right]

    def longestPalindrome(self, s: str) -> str:
        res = ""
        for i in range(len(s)):
            s1 = self.solve(s, i, i)
            s2 = self.solve(s, i, i + 1)
            if len(s1) > len(res):
                res = s1
            if len(s2) > len(res):
                res = s2
        return res

Longest Palindromic Substring

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

 

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.