Create all_subnotes_bst.py

dynamic_programming/all_subnotes_bst.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+# author: bt3gl
+
+
+class TreeNode:
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+
+def all_possible_bst(start, end, memo):
+
+        result = []
+        if start > end:
+            result.append(None)
+            return result
+        
+        if (start, end) in memo:
+            return memo[(start, end)]
+
+        for i in range(start, end + 1):
+            left = all_possible_bst(start, i-1, memo)
+            right = all_possible_bst(i+1, end, memo)
+
+            for l in left:
+                for r in right:
+                    root = TreeNode(i, l, r)
+                    result.append(root)
+
+        memo[(start, end)] = result
+        return result
+
+
+def generateTrees(n) -> List[Optional[TreeNode]]:
+
+    memo = {}
+    return all_possible_bst(1, n, memo)