def test_preorder_iterative_traversal_for_large_binary_tree(self):
node_9 = TreeNode(9)
node_11 = TreeNode(11)
node_37 = TreeNode(37)
node_21 = TreeNode(21, left=node_9)
node_49 = TreeNode(49, right=node_11)
node_17 = TreeNode(17, left=node_37)
node_77 = TreeNode(77, left=node_49, right=node_17)
node_7 = TreeNode(7, right=node_21)
root = TreeNode(100, left=node_7, right=node_77)
self.assertEqual(
Tree().preorder_iterative_traversal(root=root),
[100, 7, 21, 9, 77, 49, 11, 17, 37],
)
def test_preorder_recursive_traversal_for_null_binary_tree(self):
root = TreeNode()
self.assertEqual(Tree().preorder_recursive_traversal(root=root), [0])
def test_preorder_iterative_traversal_for_simple_binary_tree(self):
root = TreeNode(val=1, left=TreeNode(val=2))
self.assertEqual(Tree().preorder_iterative_traversal(root=root),
[1, 2])
def test_preorder_iterative_traversal_for_medium_binary_tree(self):
root = TreeNode(1, right=TreeNode(2, left=TreeNode(3)))
self.assertEqual(Tree().preorder_iterative_traversal(root=root),
[1, 2, 3])
def test_preorder_iterative_traversal_for_single_node_binary_tree(self):
root = TreeNode(val=5, left=None, right=None)
self.assertEqual(Tree().preorder_iterative_traversal(root=root), [5])