def create_preorder_inorder(preorder, prerange, inorder, inrange):
pre_left, pre_right = prerange
if pre_right - pre_left == 0:
return TreeNode(preorder[pre_right])
# find root in preorder
value = preorder[pre_left]
node = TreeNode(value)
# find root in inorder
in_left, in_right = inrange
i = in_left
while i <= in_right:
if inorder[i] == value:
break
i += 1
# get left node
left_inorder = (in_left, i - 1)
left_diff = (i - 1) - in_left
left_preorder = (pre_left + 1, pre_left + left_diff + 1)
node.left = create_preorder_inorder(preorder, left_preorder, inorder,
left_inorder)
# get right node
right_inorder = (i + 1, in_right)
right_diff = in_right - (i + 1)
right_preorder = (pre_right - right_diff, pre_right)
node.right = create_preorder_inorder(preorder, right_preorder, inorder,
right_inorder)
return node
def create_postorder_inorder(postorder, postrange, inorder, inrange):
post_left, post_right = postrange
if post_right - post_left == 0:
return TreeNode(postorder[post_right])
# find root in postorder
value = postorder[post_right]
node = TreeNode(value)
# find root in inorder
in_left, in_right = inrange
i = in_left
while i <= in_right:
if inorder[i] == value:
break
i += 1
# generate left node
left_inrange = (in_left, i - 1)
left_diff = (i - 1) - in_left
left_postrange = (post_left, post_left + left_diff)
node.left = create_postorder_inorder(postorder, left_postrange, inorder,
left_inrange)
# generate right node
right_inrange = (i + 1, in_right)
right_diff = in_right - (i + 1)
right_postrange = (post_right - right_diff - 1, post_right - 1)
node.right = create_postorder_inorder(postorder, right_postrange, inorder,
right_inrange)
return node
def create_bst_from_array(arr, left, right):
if left > right:
return None
middle = (left + right) // 2
result = TreeNode(arr[middle])
result.left = create_bst_from_array(arr, left, middle - 1)
result.right = create_bst_from_array(arr, middle + 1, right)
return result
def test_count_unival_full(self):
root = TreeNode(0)
root.left = TreeNode(1)
root.right = TreeNode(0)
root.right.left = TreeNode(1)
root.right.right = TreeNode(0)
root.right.left.left = TreeNode(1)
root.right.left.right = TreeNode(1)
assert count_unival(root) == 5
def test_symmetric_good(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.left.left = TreeNode(3)
root.left.right = TreeNode(4)
root.right = TreeNode(2)
root.right.left = TreeNode(4)
root.right.right = TreeNode(3)
assert symmetry.isTreeSymmetric(root)
def test_is_bst_bad_basic(self, func):
root = TreeNode(2)
root.left = TreeNode(1)
root.right = TreeNode(4)
root.right.left = TreeNode(6)
root.right.right = TreeNode(5)
assert func(root) is False
def test_count_complete_small(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)
assert count_complete(root) == 5
def test_is_bst_good_basic(self, func):
root = TreeNode(2)
root.left = TreeNode(1)
root.right = TreeNode(4)
root.right.left = TreeNode(3)
root.right.right = TreeNode(5)
assert func(root) is True
def test_count_unival_partial_2(self):
root = TreeNode(5)
root.left = TreeNode(5)
root.left.left = TreeNode(5)
root.right = TreeNode(5)
root.right.right = TreeNode(5)
assert count_unival(root) == 5
def test_remove_bad_edge(self):
root = TreeNode(6)
root.left = TreeNode(3)
root.right = TreeNode(8)
root.left.left = TreeNode(2)
root.left.left.right = TreeNode(8)
remove_bad_edge(root)
assert root.right is None
def huffman(frequencies):
result = {}
least_queue = []
for ch, freq in frequencies.items():
heapq.heappush(least_queue, (freq, TreeNode(ch)))
while len(least_queue) > 1:
l_freq, l_node = heapq.heappop(least_queue)
r_freq, r_node = heapq.heappop(least_queue)
i_node = TreeNode("*")
i_node.left = l_node
i_node.right = r_node
i_freq = l_freq + r_freq
heapq.heappush(least_queue, (i_freq, i_node))
l_freq, l_node = heapq.heappop(least_queue)
populate(l_node, result, "")
return result
def test_connect_nodes(self, func):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.right.left = TreeNode(5)
root.right.right = TreeNode(6)
func(root)
assert root.left.next is root.right
assert root.right.next is None
assert root.left.left.next is root.right.left
assert root.right.left.next is root.right.right
assert root.right.right.next is None
def test_is_bst_bad_left(self, func):
root = TreeNode(2)
root.left = TreeNode(1)
root.left.right = TreeNode(5)
root.left.right.left = TreeNode(3)
root.left.right.right = TreeNode(7)
assert func(root) is False
def test_inorder_optimal_moderate(self):
"""
1
/ \
2 3
/
5
/ \
8 6
"""
r = TreeNode(1)
r.left = TreeNode(2)
r.left.left = TreeNode(5)
r.left.left.left = TreeNode(8)
r.left.left.right = TreeNode(6)
r.right = TreeNode(3)
assert [n for n in inorder_optimal(r)] == [8, 5, 6, 2, 1, 3]
def test_is_balanced(self):
root = TreeNode(1)
root.insert_left(2)
root.insert_right(3)
root.left.insert_left(4)
root.left.insert_right(5)
assert is_balanced(root) is True
def test_inorder_optimal_symmetric(self):
"""
1
/ \
2 2
/ \
3 3
"""
r = TreeNode(1)
r.left = TreeNode(2)
r.left.left = TreeNode(3)
r.right = TreeNode(2)
r.right.right = TreeNode(3)
assert [n for n in inorder_optimal(r)] == [3, 2, 1, 2, 3]
def test_is_balanced_optimal_good(self):
root = TreeNode(1)
root.insert_left(2)
root.insert_right(3)
root.left.insert_left(4)
root.left.insert_right(5)
balanced, _ = is_balanced_optimal(root)
assert balanced is True
def test_inorder_optimal_simple(self):
"""
1
/ \
2 3
"""
r = TreeNode(1)
r.left = TreeNode(2)
r.right = TreeNode(3)
assert [n for n in inorder_optimal(r)] == [2, 1, 3]
def test_duplicate_subtree(self):
root = TreeNode("A")
root.left = TreeNode("B")
root.left.left = TreeNode("D")
root.left.right = TreeNode("E")
root.right = TreeNode("C")
root.right.right = TreeNode("B")
root.right.right.left = TreeNode("D")
root.right.right.right = TreeNode("E")
assert duplicate_subtree(root) is True
def test_root(self):
root = TreeNode(1)
assert root.value == 1
assert root.left is None
assert root.right is None
def test_children(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
assert root.left.value == 2
assert root.right.value == 3
def test_count_complete_big(self):
root = TreeNode(1)
root.left = TreeNode(2)
root.right = TreeNode(3)
root.left.left = TreeNode(4)
root.left.right = TreeNode(5)
root.right.left = TreeNode(6)
root.right.right = TreeNode(7)
root.left.left.left = TreeNode(8)
root.left.left.right = TreeNode(9)
root.left.right.left = TreeNode(10)
root.left.right.right = TreeNode(11)
assert count_complete(root) == 11