def bst_sequences_backtrack(nums: List[int]) -> List[List[int]]:
tree = Tree.create_bst(tree_vals)
root = tree.root
ret = []
level = 0
# use level to trace the depth for recusion for debugging
def backtrack(choices, weave, level=0):
if not choices:
ret.append(weave)
for i in range(len(choices)):
# pick node to put in weave
node = choices[i]
# new next choices = remaning next choices + the picked node's children
next_choices = choices[:i] + choices[i + 1:]
if node.left: next_choices.append(node.left)
if node.right: next_choices.append(node.right)
backtrack(next_choices, weave + [node.val], level + 1)
backtrack([root], [])
return ret
def bst_sequences(nums: List[int]) -> List[List[int]]:
tree = Tree.create_bst(tree_vals)
root = tree.root
def fn(node) -> List[List[int]]:
if not node:
return [[]]
ret = []
left = fn(node.left)
right = fn(node.right)
for seq_left in left:
for seq_right in right:
weave(seq_left, seq_right, [node.val], ret)
return ret
return fn(root)
