Longest Palindromic Substring

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

A palindrome is a string that reads the same forwards and backwards.

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Example 1

Input: s = "babad"
Output: "bab"
Explanation: "aba" is also a valid answer because both are length-3 palindromes.

Example 2

Input: s = "cbbd"
Output: "bb"
Explanation: The longest palindromic substring is "bb" with length 2.

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Constraints

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