Python版的 class BinaryTreeNode(object): def __init__(self, val): self.val = val self.left = None self.right = None def _find_parent(nodes, i): i_parent = -1 max_min_val = -float('inf') for j in range(i): if max_min_val < nodes[j].val < nodes[i].val: max_min_val = nodes[j].val i_parent = j return i_parent def gen_bst(arr, n): if not arr: return nodes = [] for num in arr: nodes.append(BinaryTreeNode(num)) for i in range(1, n): if nodes[i].val < nodes[i - 1].val: nodes[i - 1].left = nodes[i] else: i_parent = _find_parent(nodes, i) nodes[i_parent].right = nodes[i] return nodes[0] def level_order(root): ret = [] if not root: return ret queue = [root] while queue: cur = queue.pop(0) ret.append(cur.val) if cur.left: queue.append(cur.left) if cur.right: queue.append(cur.right) return ret if __name__ == '__main__': arr = [8, 3, 1, 6, 4, 7, 10, 14, 13] n = 9 root = gen_bst(arr, n) ret = level_order(root) print(' '.join([str(num) for num in ret]))