curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65d8a90640d40c2927ebbd94.md
Next, you'll work on the delete method.
Within the BinarySearchTree class, define a delete method. It takes two parameters: self and key.
key is the value that the user wants to delete from the binary search tree.
You should define a delete method with two parameters: self and key. Remember to use pass.
({ test: () => assert.match(code, /def\s+delete\(\s*self\s*,\s*key\s*\)/) });
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 _min_value(self, node):
while node.left is not None:
node = node.left
return node.key
--fcc-editable-region--
--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))