def helper(pre_order, cur_idx=0, min=float('-inf'), max=float('inf')):
if cur_idx >= len(pre_order):
return None, 0
cur_node = BinaryNode(pre_order[cur_idx])
cur_idx += 1
if cur_idx < len(pre_order) and min <= pre_order[cur_idx] <= cur_node.data:
cur_node.left, cur_idx = helper(pre_order, cur_idx, min, cur_node.data)
if cur_idx < len(pre_order) and cur_node.data < pre_order[cur_idx] <= max:
cur_node.right, cur_idx = helper(pre_order, cur_idx, cur_node.data, max)
return cur_node, cur_idx
def make_tree(pre_remaining, in_map, in_start=0, in_end=None): # End index exclusive
if not in_end:
in_end = len(pre_remaining)
if not pre_remaining or in_map[pre_remaining[0]] >= in_end or in_start >= in_end:
return None
cur_node = BinaryNode(pre_remaining.popleft())
left_end = in_map[cur_node.data] + 1
cur_node.left = make_tree(pre_remaining, in_start, left_end)
cur_node.right = make_tree(pre_remaining, left_end, in_end)
return cur_node
