curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65ca075e3184180309f4c1d9.md
Inside the else block, replace pass with an if statement to check if the left child of the current node is None.
When node.left is None, there is no left child. Therefore, return the right child from the new if block as a replacement.
You should remove the pass keyword from the else block.
({
test: () => {
const pyClassStr = runPython(
`str(_Node(_code).find_class("BinarySearchTree").find_function("_delete"))`
);
assert.notInclude(pyClassStr, "pass");
},
});
You should write an if statement that checks if node.left is None.
assert.match(code, /if\s+node\.left\s*is\s*None/);
You should return the right child of the current node.
assert.match(code, /return\s+node\.right/);
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:
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))