Remove Outermost Parentheses

Author: anantkaushik

1021-remove-outermost-parentheses.py

@@ -0,0 +1,51 @@
+"""
+Problem Link: https://leetcode.com/problems/remove-outermost-parentheses/ 
+
+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
+"""
+class Solution:
+    def removeOuterParentheses(self, S: str) -> str:
+        res = []
+        count = 0
+        for parentheses in S:
+            if count > 0 and parentheses == "(" or count > 1 and parentheses == ")":
+                res.append(parentheses)
+            if parentheses == "(":
+                count += 1
+            elif parentheses == ")":
+                count -= 1
+        return "".join(res)