Leetcode 5. Longest Palindromic Substring

[medium][Amazon]

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.

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),

[Gary’s brute force Java]

1. create a function to check if current string is palindromic
2. check all the string possibility to find the longest string
3. very slow, might TLE

[Second]

1. check each char in String if it can extend
2. extend(s, i, i+1) -> check answer string if it’s odd char