#289 Longest Palindromic Substring

Given a string s, find the longest substring that is a palindrome.

Rules:

• A palindrome reads the same forwards and backwards
• If multiple palindromes have same length, return any one
• String contains only letters and digits

Constraints:

• 1 ≤ s.length ≤ 1000
• s contains only digits and English letters

Examples:

// Example 1:
console.log(longestPalindrome("ababd"));
// Output: "bab"
// Explanation: "aba" would also be valid

// Example 2:
console.log(longestPalindrome("abbc"));
// Output: "bb"
// Explanation: Only palindrome of length 2