Given a string, find the longest substring that is a palindrome. A palindrome is a sequence of characters that reads the same forwards and backwards.

Your task is to implement the findLongestPalindrome method that takes a string as input and returns the longest palindromic substring.

Requirements

  • If there are multiple palindromic substrings of the same maximum length, return the first one found (leftmost)
  • Return null for null input
  • Return empty string for empty string input
  • The comparison should be case-sensitive
  • Single characters are considered palindromes

Examples

Example 1:

String input = 'babad';
String result = findLongestPalindrome(input);
// Returns: 'bab' (or 'aba' - both are valid, but 'bab' appears first)

Example 2:

String input = 'cbbd';
String result = findLongestPalindrome(input);
// Returns: 'bb'

Example 3:

String input = 'racecar';
String result = findLongestPalindrome(input);
// Returns: 'racecar' (entire string is a palindrome)

Example 4:

String input = 'a';
String result = findLongestPalindrome(input);
// Returns: 'a' (single character is a palindrome)

Example 5:

String input = null;
String result = findLongestPalindrome(input);
// Returns: null

Example 6:

String input = '';
String result = findLongestPalindrome(input);
// Returns: ''
Apex Code Editor
Sign in to Submit

Welcome to Lightning Challenge!

Create an Account

Sign up to track your progress, earn points, and compete with others. Your solutions will be saved automatically.

Create account

How It Works

  • • Write your solution in the code editor
  • • Connect your Salesforce org to test
  • • Submit to check if your solution passes
  • • Use hints if you get stuck

Contest Alert

🏆 #CodeEveryDay Jan 2026

Contest runs January 1 - 31. Complete challenges to climb the leaderboard!

Points are calculated for challenges completed during the contest period.