def check_black_height(self, ivtree):
sentinel = tu.sentinel(ivtree)
node = tu.root(ivtree)
height_stack = []
node_stack = []
# -1 = left, +1 = right
direction_stack = []
while node is not sentinel or len(node_stack) != 0:
while node is not sentinel:
node_stack.append(node)
direction_stack.append(-1)
node = nu.left(node)
height_stack.append(1)
while direction_stack[-1] == 1:
node = node_stack.pop()
direction_stack.pop()
black = nu.black(node)
right_height = height_stack.pop()
left_height = height_stack.pop()
self.assertEqual(right_height, left_height)
new_height = right_height + 1 if black else right_height
if len(node_stack) == 0:
# terminating and returning the black height of the root
return new_height
height_stack.append(new_height)
node = nu.right(node_stack[-1])
direction_stack[-1] = 1
def check_child_color(self, ivtree):
stack = []
sentinel = tu.sentinel(ivtree)
node = tu.root(ivtree)
while node is not sentinel or len(stack) > 0:
while node is not sentinel:
stack.append(node)
node = nu.left(node)
node = stack.pop()
if not nu.black(node):
self.assertTrue(nu.black(nu.left(node)))
self.assertTrue(nu.black(nu.right(node)))
node = nu.left(node)
def check_augmentation(self, tree):
sentinel = tu.sentinel(tree)
node = tu.root(tree)
node_stack = []
while node is not sentinel or len(node_stack) > 0:
while node is not sentinel:
node_stack.append(node)
node = nu.left(node)
node = node_stack.pop()
aug_end = nu.max_end(node)
if nu.left(node) is not sentinel:
left_aug_end = nu.aug_end(nu.left(node))
if left_aug_end > aug_end:
aug_end = left_aug_end
if nu.right(node) is not sentinel:
right_aug_end = nu.aug_end(nu.right(node))
if right_aug_end > aug_end:
aug_end = right_aug_end
self.assertEqual(aug_end, nu.aug_end(node))
node = nu.right(node)
def test_bad_augmentation(self):
tree = self.create_custom_tree()
root = tu.root(tree)
node2 = nu.left(root)
nu.set_aug_end(node2, 4)
self.check_augmentation(tree)
def test_bad_black_height(self):
tree = self.create_custom_tree()
root = tu.root(tree)
node3 = nu.right(root)
nu.set_black(node3, False)
self.check_black_height(tree)
def test_bad_child_color(self):
tree = self.create_custom_tree()
root = tu.root(tree)
node4 = nu.left(nu.left(root))
nu.set_black(node4, False)
self.check_child_color(tree)
def test_bad_root_color(self):
tree = self.create_custom_tree()
root = tu.root(tree)
nu.set_black(root, False)
self.check_root_color(tree)
def check_root_color(self, ivtree):
root = tu.root(ivtree)
self.assertTrue(nu.black(root))