added some recursive datastructures

recursion/recursive_datastructure/solution/trees.py

@@ -0,0 +1,33 @@
+from dataclasses import dataclass
+from enum import Enum, auto
+from typing import Iterator, Optional
+
+
+@dataclass
+class Node[T]:
+    value: T
+    left: Optional['Node[T]']
+    right: Optional['Node[T]']
+
+
+type BinaryTree[T] = Optional[Node[T]]
+
+class TraversalType(Enum):
+    INORDER, POSTORDER, PREORDER = auto(), auto(), auto()
+
+def traverse[T](tree: BinaryTree[T], order: TraversalType = TraversalType.INORDER) -> Iterator[T]:
+    match (tree, order):
+        case (Node(value, left, right), TraversalType.INORDER):
+            yield from traverse(left, order)
+            yield value
+            yield from traverse(right, order)
+        case (Node(value, left, right), TraversalType.POSTORDER):
+            yield from traverse(left, order)
+            yield from traverse(right, order)
+            yield value
+        case (Node(value, left, right), TraversalType.PREORDER):
+            yield value
+            yield from traverse(left, order)
+            yield from traverse(right, order)
+        case _:
+            return