def test_right_rotation(self):
"""
Right rotation
All nodes(Common case)
Successfully
N N
| |
(8) (6)
/ \ / \
/ \ / \
(6) 9 -> 4 (8)
/ \ / \
/ \ / \
4 7 7 9
"""
red_black_tree = RedBlackTree()
red_black_tree.insert(8)
red_black_tree.insert(9)
red_black_tree.insert(6)
red_black_tree.insert(4)
red_black_tree.insert(7)
node_to_rotate = red_black_tree.search(8)
red_black_tree._right_rotation(node_to_rotate)
new_left_node = red_black_tree.search(6)
new_right_node = red_black_tree.search(8)
assert new_right_node.parent is new_left_node
assert new_right_node.right.val == 9
assert new_right_node.right.parent is new_right_node
assert new_right_node.left.val == 7
assert new_right_node.left.parent is new_right_node
assert new_left_node.left.val == 4
assert new_left_node.left.parent is new_left_node
assert new_left_node.right is new_right_node
def test_right_rotation_with_two_nodes(self):
"""
Right rotation
Only two nodes
Successfully
N N
| |
(10) (5)
/ \ / \
/ \ / \
(5) N -> N (10)
/ \ / \
/ \ / \
N N N N
"""
red_black_tree = RedBlackTree()
red_black_tree.insert(10)
red_black_tree.insert(5)
node_to_rotate = red_black_tree.search(10)
red_black_tree._right_rotation(node_to_rotate)
new_left_node = red_black_tree.search(5)
new_right_node = red_black_tree.search(10)
assert new_right_node.parent is new_left_node
assert new_right_node.right is None
assert new_right_node.left is None
assert new_left_node.parent is None
assert new_left_node.right is new_right_node
assert new_left_node.left is None
def test_right_rotation_with_one_node(self):
"""
Right rotation
Only one node
Successfully
N N
| |
(5) -> (5)
/ \ / \
/ \ / \
(N) N (N) N
"""
red_black_tree = RedBlackTree()
red_black_tree.insert(5)
node_to_rotate = red_black_tree.search(5)
red_black_tree._right_rotation(node_to_rotate)
new_node = red_black_tree.search(5)
assert new_node is node_to_rotate
