Problem 35: Longest palindromic substring

def longest_palindrome(s: str) -> str: """ Finds the longest palindromic substring in the given string s. Uses the Expand Around Center approach. """ if not s: return "" start = 0 max_len = 1 def expand_around_center(left: int, right: int) -> int: """Expands outwards from a center point (or two center points)""" while left >= 0 and right < len(s) and s[left] == s[right]: left -= 1 right += 1 return right - left - 1 for i in range(len(s)): len1 = expand_around_center(i, i) len2 = expand_around_center(i, i + 1) current_max_len = max(len1, len2) if current_max_len > max_len: max_len = current_max_len start = i - (max_len - 1) // 2 return s[start:start + max_len]