curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65c646d4148ae3b2d1cbcac4.md
Note that, your search returns something like 80: <__main__.TreeNode object at 0x108b3e0>. This is the default string representation when printing an instance of a class.
To change that to print a useful value, define another method named __str__ in the TreeNode class. It takes a single argument self.
After defining __str__ you'll get an exception in the console because the __str__ method doesn't return anything yet. You'll work on the method body in the next step.
You should define a method __str__ that takes a single argument self. Remember to use pass.
assert.match(code, /^(\s+)def\s+__init__.+?^\1def\s+__str__\(\s*self\s*\)\s*:\s*\n^\1\1pass/ms)
class TreeNode:
def __init__(self, key):
self.key = key
self.left = None
self.right = None
--fcc-editable-region--
--fcc-editable-region--
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)
bst = BinarySearchTree()
nodes = [50, 30, 20, 40, 70, 60, 80]
for node in nodes:
bst.insert(node)
print('Search for 80:', bst.search(80))