def test(solution):
print('testing:', solution.__name__)
l1 = TreeNode(15, TreeNode(18, TreeNode(20)))
assert not solution(l1)
l2 = TreeNode(7)
assert solution(l2)
l3 = TreeNode(11, l1, l2)
assert not solution(l3)
r1 = TreeNode(6)
assert solution(r1)
r2 = TreeNode(8, None, r1)
assert solution(r2)
tree = TreeNode(9, l3, r2)
assert not solution(tree)
assert solution(create_valid_bst())
print('passed')
4
/ \
7 2
/ \ / \
9 6 3 1
"""
def invert_tree(root):
if not root:
return
tmp = root.right
root.right = root.left
root.left = tmp
invert_tree(root.left)
invert_tree(root.right)
return root
if __name__ == '__main__':
print('before:')
tree = create_valid_bst()
level_order(tree)
print('\nafter:')
tree = invert_tree(tree)
level_order(tree)