def test_left_rotation(self):
"""
Left rotation
All nodes(Common case)
Successfully
N N
| |
(5) (7)
/ \ / \
/ \ / \
4 (7) -> (5) 8
/ \ / \
/ \ / \
6 8 4 6
"""
red_black_tree = RedBlackTree()
red_black_tree.insert(5)
red_black_tree.insert(4)
red_black_tree.insert(7)
red_black_tree.insert(6)
red_black_tree.insert(8)
node_to_rotate = red_black_tree.search(5)
red_black_tree._left_rotation(node_to_rotate)
new_left_node = red_black_tree.search(5)
new_right_node = red_black_tree.search(7)
assert new_right_node.parent is None
assert new_right_node.right.val == 8
assert new_right_node.right.parent is new_right_node
assert new_right_node.left is new_left_node
assert new_left_node.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.val == 6
assert new_left_node.right.parent is new_left_node
def test_left_rotation_with_two_nodes(self):
"""
Left rotation
Only two nodes
Successfully
N N
| |
(5) (10)
/ \ / \
/ \ / \
N (10) -> (5) N
/ \ / \
/ \ / \
N N N N
"""
red_black_tree = RedBlackTree()
red_black_tree.insert(5)
red_black_tree.insert(10)
node_to_rotate = red_black_tree.search(5)
red_black_tree._left_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 None
assert new_right_node.right is None
assert new_right_node.left is new_left_node
assert new_left_node.parent is new_right_node
assert new_left_node.right is None
assert new_left_node.left is None
def test_left_rotation_with_one_node(self):
"""
Left 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._left_rotation(node_to_rotate)
new_node = red_black_tree.search(5)
assert new_node is node_to_rotate
