dynamic_programming/regex_match.py

@@ -30,11 +30,17 @@ def recursive_match(text: str, pattern: str) -> bool:
     >>> recursive_match('aa', '.*')
     True
     """
-    if not pattern:
-        return not text
+    if not text and not pattern:
+        return True
 
-    if not text:
-        return pattern[-1] == "*" and recursive_match(text, pattern[:-2])
+    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])
@@ -74,16 +80,19 @@ def dp_match(text: str, pattern: str) -> bool:
     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] in {".", text[i - 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]
-                if pattern[j - 2] in {".", text[i - 1]}:
+                if pattern[j - 2] == "." or pattern[j - 2] == text[i - 1]:
                     dp[i][j] |= dp[i - 1][j]
             else:
                 dp[i][j] = False