[Python] Longest Palindromic Substring - LeetCode

5. Longest Palindromic Substring

Longest Palindromic Substring - LeetCode

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.

2:

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

3:

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

4:

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

Constraints:

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

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Python solution

class Solution:
    def longestPalindrome(self, s: str) -> str:
        if len(s) <= 1:
            return s

        i = l = 0
        for j in range(len(s)):
            if s[j-l: j+1] == s[j-l: j+1][::-1]:
                i = j-l
                l += 1
            elif j-l > 0 and s[j-l-1: j+1] == s[j-l-1: j+1][::-1]:
                i = j-l-1
                l += 2

        return s[i: i+l]

Accepted 104ms runtime

Submission detail