Add recursive solution to regex_match.py

dynamic_programming/regex_match.py

@@ -0,0 +1,53 @@
+"""
+Regex matching check if a text matches wildcard pattern or not.
+Pattern:
+    '.' Matches any single character.
+    '*' Matches zero or more of the preceding element.
+"""
+
+
+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
+    """
+    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
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()