curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65ca0794ec3ed103bca67ed7.md
Below the if statement, add an elif clause to check if the right child of the current node (node.right) is None.
If the previous condition is met, it means there is no right child. So, return the left child of the current node from the elif block as a replacement.
You should create an elif statement that checks if the right child of the current node is None.
({test: () => assert(runPython(`_Node(_code).find_class("BinarySearchTree").find_function("_delete").find_ifs()[1].find_conditions()[3].is_equivalent("node.right is None")`))})
You should return the left child of the current node.
({test: () => assert(runPython(`_Node(_code).find_class("BinarySearchTree").find_function("_delete").find_ifs()[1].find_bodies()[3].is_equivalent("return node.left")`))})
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)
--fcc-editable-region--
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
--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))