def test_avl_insertion():
"""Tests that avl insertion maintains balance"""
bintree = AVLTree()
for i in xrange(100):
bintree.insert(random.randint(0, 1e6))
assert bintree.size() == 100
assert abs(bintree.balance()) < 2
assert bintree.depth() < 9 # 2 ** 7 is 128, it should fit
def test_avl_deletion():
"""Tests that avl deletion maintains balance"""
bintree = AVLTree()
bintree.insert(10)
bintree.insert(5)
bintree.insert(15)
bintree.insert(2)
bintree.insert(7)
bintree.insert(12)
bintree.insert(30)
bintree.insert(1)
bintree.insert(11)
bintree.insert(13)
bintree.insert(35)
bintree.insert(14)
# 10
# / \
# 5 15
# / \ / \
# 2 7 12 30
# / / \ \
# 1 11 13 35
# \
# 14
# All inserted in an order such that no rotations occurred
assert bintree.depth() == 5
assert bintree.balance() == -1
assert bintree.size() == 12
bintree.delete(15)
# 10
# / \
# 5 14
# / \ / \
# 2 7 12 30
# / / \ \
# 1 11 13 35
# This is standard deletion, still in balance.
# check that balance/depth update correctly
assert bintree.balance() == 0
assert bintree.depth() == 4
assert bintree.size() == 11
assert bintree.rightchild.depth() == 3
assert bintree.rightchild.leftchild.depth() == 2
assert bintree.rightchild.leftchild.balance() == 0 # used to be -1
bintree.delete(7)
# 10
# / \
# 5 14
# / / \
# 2 12 30
# / / \ \
# 1 11 13 35
# Now 5 is out of balance, rotate left up
# 10
# / \
# 2 14
# / \ / \
# 1 5 12 30
# / \ \
# 11 13 35
assert bintree.leftchild.value == 2
assert bintree.balance() == -1
assert bintree.depth() == 4
assert bintree.leftchild.depth() == 2
assert bintree.leftchild.rightchild.depth() == 1
bintree.delete(10)
# 11
# / \
# 2 14
# / \ / \
# 1 5 12 30
# \ \
# 13 35
# Just normal deletion
bintree.delete(11)
# 12
# / \
# 2 14
# / \ / \
# 1 5 13 30
# \
# 35
# Just normal deletion
bintree.delete(12)
# 13
# / \
# 2 14
# / \ \
# 1 5 30
# \
# 35
# Now 14 is out of balance, rotate 30 up
# 13
# / \
# 2 30
# / \ / \
# 1 5 14 35
assert bintree.depth() == 3
assert bintree.balance() == 0
assert bintree.value == 13
assert bintree.leftchild.value == 2
assert bintree.rightchild.value == 30
assert bintree.leftchild.depth() == 2
assert bintree.rightchild.depth() == 2
def test_rotations():
"""Tests my rotations, balance, and depth with a simple AVLtree"""
# Initialization etc. should work fine, just inherits from well-tested BST
bintree = AVLTree()
assert bintree.depth() == 0
with pytest.raises(ValueError):
bintree._rotate_left()
bintree.insert(5)
assert bintree.depth() == 1
with pytest.raises(ValueError):
bintree._rotate_left()
with pytest.raises(ValueError):
bintree._rotate_right()
bintree.insert(3)
assert bintree.depth() == 2
with pytest.raises(ValueError):
bintree._rotate_right() # 3 is on left
bintree._rotate_left() # 3 now head
bintree._rotate_right() # 5 is head again
bintree.insert(7)
bintree.insert(6)
bintree.insert(2)
bintree.insert(4)
bintree.insert(1)
bintree.insert(9)
bintree.insert(10) # All in order, no rotations done
# 5
# / \
# 3 7
# /\ / \
# 2 4 6 9
# | |
# 1 10
bintree._rotate_right()
# 7
# / \
# 5 9
# | \ \
# 3 6 10
# /\
# 2 4
# |
# 1
assert bintree.value == 7
assert bintree.balance() == 2
assert bintree.size() == 9
assert bintree.depth() == 5
assert bintree.rightchild.value == 9
assert bintree.leftchild.value == 5
assert bintree.leftchild.rightchild.value == 6
bintree.leftchild._rotate_left()
# Note that this breaks stuff at head; the update of depth/_level is part
# of insert()/delete(), so 7 never gets releveled without the next line
bintree._relevel()
# 7
# / \
# 3 9
# | \ \
# 2 5 10
# / / \
# 1 4 6
assert bintree.balance() == 1
assert bintree.depth() == 4
pivot_node = bintree.leftchild
assert pivot_node.value == 3
assert pivot_node.leftchild.value == 2
assert pivot_node.rightchild.value == 5
