22 Generate Parentheses.py

Author: peihenglyu

22 Generate Parentheses.py

@@ -0,0 +1,46 @@
+# class Solution(object):
+#     def generateParenthesis(self, n):
+#         """
+#         :type n: int
+#         :rtype: List[str]
+#         """
+#         pa_list = ["("]
+#         count = 1
+#         while count < n*2:
+#             new_list = []
+#             for pa in pa_list:
+#                 left_count = pa.count("(")
+#                 right_count = pa.count(")")
+#                 if right_count < left_count:
+#                     new_list.append(pa + ")")
+#                 if left_count < n:
+#                     new_list.append(pa + "(")
+#             pa_list = new_list
+#             count += 1
+
+#         return pa_list
+    
+class Solution(object):
+    def generateParenthesis(self, n):
+        """
+        :type n: int
+        :rtype: List[str]
+        """
+        pa_list = []
+        def genereat_pa(cur, left_count, right_count):
+            if len(cur) == n*2:
+                pa_list.append(cur)
+            
+            if left_count < n:
+                genereat_pa(cur + "(", left_count + 1, right_count)
+
+            if right_count < left_count:
+                genereat_pa(cur + ")", left_count, right_count + 1)
+        
+        genereat_pa("", 0, 0)
+        return pa_list
+
+obj = Solution()
+print(obj.generateParenthesis(1))
+print(obj.generateParenthesis(3))
+print(obj.generateParenthesis(7))