https://leetcode.com/problems/longest-palindromic-substring/description/ Longest Palindromic Substring - LeetCode Longest Palindromic Substring - 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