Fixes #9920

backtracking/generate_parenthesis.py

@@ -0,0 +1,64 @@
+"""
+    Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.
+    Constraints: 1 <= n <= 8
+    Problem source: https://leetcode.com/problems/generate-parentheses/
+"""
+
+class Solution:
+    def generateParenthesis(self, n):
+        valid = []
+
+        # Helper function to generate valid combinations
+        def generate(s, open_count, close_count):
+            if open_count == 0 and close_count == 0:
+                valid.append(s)
+                return
+
+            if open_count > 0:
+                s += '('
+                generate(s, open_count - 1, close_count)
+                s = s[:-1]
+
+            if close_count > 0 and open_count < close_count:
+                s += ')'
+                generate(s, open_count, close_count - 1)
+                s = s[:-1]
+
+        if n < 0:
+            raise ValueError("Input value must be non-negative")
+
+        # Start the generation process with an empty string and n opening and closing parentheses
+        generate('', n, n)
+        """
+        The function employs backtracking to generate all valid combinations of n pairs of parentheses. It maintains two counters, open_count and close_count, representing available open and close parentheses.
+
+        It starts with an empty string s and both counters set to n.
+
+        It recursively explores two possibilities:
+
+        Adding an open parenthesis '(' if open_count > 0.
+        Adding a close parenthesis ')' if close_count > 0 and there are open parentheses available (i.e., open_count < close_count).
+        When both counters reach zero, it means a valid combination is formed, and it's added to the valid list.
+
+        The code then tries different combinations by backtracking (removing the last added parenthesis) and continues until all possibilities are exhausted.
+
+        The input is validated to ensure it's a non-negative integer, and a ValueError is raised for invalid input.
+
+        The valid combinations are returned as the result.
+        """
+
+        return valid
+
+
+try:
+    # Input the value of n from the user
+    n = int(input("Enter a value for n: "))
+
+    # Create an instance of the Solution class and generate valid combinations
+    solution = Solution()
+    result = solution.generateParenthesis(n)
+
+    # Return the valid combinations
+    print(result)
+except ValueError:
+    print("Invalid input. Please enter a non-negative integer.")