""" Regex matching check if a text matches wildcard pattern or not. Pattern: '.' Matches any single character. '*' Matches zero or more of the preceding element. More info: https://medium.com/trick-the-interviwer/regular-expression-matching-9972eb74c03 """ def recursive_match(text: str, pattern: str) -> bool: """ Recursive matching algorithm. Time complexity: O(2 ^ (m + n)), where m is the length of text and n is the length of pattern. Space complexity: Recursion depth is O(m + n). :param text: Text to match. :param pattern: Pattern to match. :return: True if text matches pattern, False otherwise. >>> recursive_match('abc', 'a.c') True >>> recursive_match('abc', 'af*.c') True >>> recursive_match('abc', 'a.c*') True >>> recursive_match('abc', 'a.c*d') False >>> recursive_match('aa', '.*') True """ if not text and not pattern: return True if text and not pattern: return False if not text and pattern and pattern[-1] != '*': return False if not text and pattern and pattern[-1] == '*': return recursive_match(text, pattern[:-2]) if text[-1] == pattern[-1] or pattern[-1] == '.': return recursive_match(text[:-1], pattern[:-1]) if pattern[-1] == '*': return recursive_match(text[:-1], pattern) or recursive_match(text, pattern[:-2]) return False def dp_match(text: str, pattern: str) -> bool: """ Dynamic programming matching algorithm. Time complexity: O(m * n), where m is the length of text and n is the length of pattern. Space complexity: O(m * n). :param text: Text to match. :param pattern: Pattern to match. :return: True if text matches pattern, False otherwise. >>> dp_match('abc', 'a.c') True >>> dp_match('abc', 'af*.c') True >>> dp_match('abc', 'a.c*') True >>> dp_match('abc', 'a.c*d') False >>> dp_match('aa', '.*') True """ m = len(text) n = len(pattern) dp = [[False for _ in range(n + 1)] for _ in range(m + 1)] dp[0][0] = True for i in range(1, m + 1): dp[i][0] = False for j in range(1, n + 1): dp[0][j] = pattern[j - 1] == '*' and dp[0][j - 2] for i in range(1, m + 1): for j in range(1, n + 1): if pattern[j - 1] == '.' or pattern[j - 1] == text[i - 1]: dp[i][j] = dp[i - 1][j - 1] elif pattern[j - 1] == '*': dp[i][j] = dp[i][j - 2] or (dp[i - 1][j] and (pattern[j - 2] == '.' or pattern[j - 2] == text[i - 1])) else: dp[i][j] = False return dp[m][n] if __name__ == "__main__": import doctest doctest.testmod()