Remove_Invalid_Parenthesis.py

backtracking/remove_invalid_parenthesis.py

@@ -0,0 +1,52 @@
+def isParenthesis(c):
+    return (c == "(") or (c == ")")
+
+
+def isValidString(str):
+    cnt = 0
+    for i in range(len(str)):
+        if str[i] == "(":
+            cnt += 1
+        elif str[i] == ")":
+            cnt -= 1
+        if cnt < 0:
+            return False
+    return cnt == 0
+
+
+# method to remove invalid parenthesis
+def removeInvalidParenthesis(str):
+    if len(str) == 0:
+        return
+
+    visit = set()
+
+    q = []
+    temp = 0
+    level = 0
+
+    q.append(str)
+    visit.add(str)
+    while len(q):
+        str = q[0]
+        q.pop(0)
+        if isValidString(str):
+            print(str)
+
+            level = True
+        if level:
+            continue
+        for i in range(len(str)):
+            if not isParenthesis(str[i]):
+                continue
+
+            temp = str[0:i] + str[i + 1 :]
+            if temp not in visit:
+                q.append(temp)
+                visit.add(temp)
+
+
+expression = "()())()"
+removeInvalidParenthesis(expression)
+expression = "()v)"
+removeInvalidParenthesis(expression)