def delete(self, value):
'''Delete a BTNode that contains value value from this BST. If there
is no such BTNode, raise a NoSuchValueException.
'''
# special case: empty tree
if self._root is None:
raise NoSuchValueException
# special case: deleting a root
if self._root.value == value:
# create a fake root (use min - 1 as value), then remove root
fake_root = BTNode(_get_min(self._root) - 1)
fake_root.right = self._root
_delete(fake_root, self._root.value, None)
self._root = fake_root.right
else:
_delete(self._root, value, None)
def _delete_node(node, parent):
'''Remove the BTNode node from the tree rooted at BTNode.
Pre: parent is the BTNode parent of node
node is not None
Hint: this is where you use get_min
'''
# leaf is included in this case; where node.left == None
if node.right is None:
_update_parent(node, parent, node.left)
# Need to delete the min node and update parent
else:
min_value = _get_min(node.right)
substitute = BTNode(min_value)
_delete(node, min_value, parent)
substitute.left = node.left
substitute.right = node.right
_update_parent(node, parent, substitute)
def delete(self, value):
'''Delete a BTNode that contains value value from this BST. If there
is no such BTNode, raise a NoSuchValueException.
'''
# this one will take a bit longer :)
# special case: empty tree
if self._root is None:
raise NoSuchValueException
# special case: deleting a root
if self._root.value == value:
# create a fake root (use min - 1 as value), then remove root
fake_root = BTNode(_get_min(self._root) - 1)
fake_root.right = self._root
_delete(fake_root, self._root.value, None)
self._root = fake_root.right
else:
_delete(self._root, value, None)
# Still don't understand why case 1 doesn't work
"""