curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65ca1181e5b9b41c47632127.md
Inside the inorder_traversal method, replace pass with an empty list named result that will store the keys of the nodes in sorted order.
You should remove the pass keyword from the inorder_traversal method.
({
test: () => {
assert.isFalse(
runPython(
`_Node(_code).find_class("BinarySearchTree").find_function("inorder_traversal").has_pass()`
)
);
},
});
You should initialize an empty list named result inside the method.
({ test: () => assert.match(code, /result\s*=\s*\[\s*\]/) })
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):
pass
--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))