curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65ca11a86801bc1d254da83c.md
Within the inorder_traversal method, start the in-order traversal by calling the helper method _inorder_traversal and pass the BST root and the result list as the arguments.
This will start the traversal from the root of the binary search tree (self.root), and the result list will be passed to accumulate the keys during the traversal.
You should call _inorder_traversal and pass self.root and result as the arguments.
({ test: () => assert.match(code, /self\._inorder_traversal\(\s*self\.root\s*,\s*result\s*\)/) })
class TreeNode:
def __init__(self, key):
self.key = key
self.left = None
self.right = None
def __str__(self):
return str(self.key)
class BinarySearchTree:
def __init__(self):
self.root = None
def _insert(self, node, key):
if node is None:
return TreeNode(key)
if key < node.key:
node.left = self._insert(node.left, key)
elif key > node.key:
node.right = self._insert(node.right, key)
return node
def insert(self, key):
self.root = self._insert(self.root, key)
def _search(self, node, key):
if node is None or node.key == key:
return node
if key < node.key:
return self._search(node.left, key)
return self._search(node.right, key)
def search(self, key):
return self._search(self.root, key)
def _delete(self, node, key):
if node is None:
return node
if key < node.key:
node.left = self._delete(node.left, key)
elif key > node.key:
node.right = self._delete(node.right, key)
else:
if node.left is None:
return node.right
elif node.right is None:
return node.left
node.key = self._min_value(node.right)
node.right = self._delete(node.right, node.key)
return node
def delete(self, key):
self.root = self._delete(self.root, key)
def _min_value(self, node):
while node.left is not None:
node = node.left
return node.key
def _inorder_traversal(self, node, result):
if node:
self._inorder_traversal(node.left, result)
result.append(node.key)
self._inorder_traversal(node.right, result)
--fcc-editable-region--
def inorder_traversal(self):
result = []
--fcc-editable-region--
bst = BinarySearchTree()
nodes = [50, 30, 20, 40, 70, 60, 80]
for node in nodes:
bst.insert(node)
# print('Search for 80:', bst.search(80))