class BST:
"""
Test insert
>>> bst.insert_node(25)
>>> bst.root.data
25
>>> bst.insert_node(20)
>>> bst.insert_node(15)
Test search
>>> bst.search(2)
False
>>> bst.search(15)
True
>>> bst.maximum_value()
25
>>> bst.minimum_value()
15
>>> bst.insert_node(27)
>>> bst.insert_node(30)
>>> bst.insert_node(28)
>>> bst.insert_node(26)
>>> bst.maximum_value()
30
>>> bst.minimum_value()
15
Test delete root
>>> bst.search(25)
True
>>> bst.root.data
25
>>> bst.delete_node(25)
>>> bst.root.data
26
>>> bst.search(25)
False
Test delete leaf node
>>> bst.search(15)
True
>>> bst.delete_node(15)
>>> bst.search(15)
False
Test delete node with left child only
>>> bst.insert_node(14)
>>> bst.root.left_child.data
20
>>> bst.delete_node(20)
>>> bst.root.left_child.data
14
>>> bst.insert_node(29)
>>> bst.search(28)
True
>>> bst.delete_node(28)
>>> bst.search(28)
False
>>> bst.delete_node(8)
"""
def __init__(self, root=None):
self.root = root
def insert_node(self, value):
if self.root:
self.root.insert(value)
else:
self.root = TreeNode(value)
def print_tree(self):
if self.root:
self.root.traverse_inorder()
print()
else:
print("Tree is empty")
def search(self, key):
if self.root:
return self.root.find_key(key)
else:
return None
def maximum_value(self):
if self.root:
return self.root.get_max()
def minimum_value(self):
if self.root:
return self.root.get_min()
def delete_node(self, key):
self.root = self._node_replacement(self.root, key)
def _node_replacement(self, subtree_root, key):
if subtree_root is None:
return subtree_root
if key < subtree_root.data:
subtree_root.left_child = self._node_replacement(
subtree_root.left_child, key)
elif key > subtree_root.data:
subtree_root.right_child = self._node_replacement(
subtree_root.right_child, key)
else:
# case 1 and case 2
if subtree_root.left_child is None:
return subtree_root.right_child
if subtree_root.right_child is None:
return subtree_root.left_child
# case 3 -> has 2 children
# find min node on the right child
# copy min value to the current subtree root.
# delete the min node from the right child
min_node = subtree_root.right_child.get_min()
subtree_root.data = min_node
subtree_root.right_child = self._node_replacement(
subtree_root.right_child, min_node)
return subtree_root
