1021 Remove Outermost Parentheses.py

Author: rajeevranjancom

1021 Remove Outermost Parentheses.py

@@ -0,0 +1,96 @@
+#!/usr/bin/python3
+"""
+A valid parentheses string is either empty (""), "(" + A + ")", or A + B, where
+A and B are valid parentheses strings, and + represents string concatenation.
+For example, "", "()", "(())()", and "(()(()))" are all valid parentheses strings.
+
+A valid parentheses string S is primitive if it is nonempty, and there does not
+exist a way to split it into S = A+B, with A and B nonempty valid parentheses
+strings.
+
+Given a valid parentheses string S, consider its primitive decomposition:
+S = P_1 + P_2 + ... + P_k, where P_i are primitive valid parentheses strings.
+
+Return S after removing the outermost parentheses of every primitive string in
+the primitive decomposition of S.
+
+Example 1:
+Input: "(()())(())"
+Output: "()()()"
+Explanation:
+The input string is "(()())(())", with primitive decomposition "(()())" + "(())".
+After removing outer parentheses of each part, this is "()()" + "()" = "()()()".
+
+Example 2:
+Input: "(()())(())(()(()))"
+Output: "()()()()(())"
+Explanation:
+The input string is "(()())(())(()(()))", with primitive decomposition
+"(()())" + "(())" + "(()(()))".
+After removing outer parentheses of each part, this is "()()" + "()" +
+"()(())" = "()()()()(())".
+
+Example 3:
+Input: "()()"
+Output: ""
+Explanation:
+The input string is "()()", with primitive decomposition "()" + "()".
+After removing outer parentheses of each part, this is "" + "" = "".
+
+
+Note:
+S.length <= 10000
+S[i] is "(" or ")"
+S is a valid parentheses string
+"""
+from collections import deque
+
+
+class Solution:
+    def removeOuterParentheses(self, S: str) -> str:
+        """
+        Primitive parentheses will have equal number of opened and closed
+        parentheses.
+
+        Use count
+        Exclude the first and last parathesis
+        """
+        ret = []
+        cnt = 0
+        for e in S:
+            if e == "(":
+                cnt += 1
+                if cnt > 1:
+                    ret.append(e)
+            else:
+                cnt -= 1
+                if cnt > 0:
+                    ret.append(e)
+
+        return "".join(ret)
+
+
+    def removeOuterParentheses_error(self, S: str) -> str:
+        """
+        stack + deque
+        """
+        ret = []
+        stk = []
+        cur_q = deque()
+        for e in S:
+            if e == "(":
+                stk.append(e)
+            else:
+                prev = stk.pop()
+                if stk:
+                    cur_q.appendleft(prev)
+                    cur_q.append(e)
+                else:
+                    ret.extend(cur_q)
+                    cur_q = deque()
+
+        return "".join(ret)
+
+
+if __name__ == "__main__":
+    assert Solution().removeOuterParentheses("(()())(())(()(()))") == "()()()()(())"