63. Longest Palindromic Substring

You're building a text analysis feature that needs to find the longest palindromic substring. This is useful for text processing, pattern matching, and string analysis.

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

A palindrome is a string that reads the same backward as forward.

Requirements

1. Basic Functionality

• Find longest palindromic substring
• Handle odd and even length palindromes
• Return the substring itself
• Handle edge cases (single character, no palindrome)

Example Usage

longestPalindrome("babad"); // "bab" or "aba"
longestPalindrome("cbbd");  // "bb"
longestPalindrome("a");     // "a"

Real-World Context

This problem models real text processing scenarios:

• Text analysis: Find longest palindrome
• Pattern matching: Palindrome detection
• String processing: Substring analysis
• Algorithm design: Expand around centers