python中的二叉树排序用法及说明

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def binary_tree_sort(arr):
    if not arr:
        return []
    
    # 构建二叉搜索树
    root = TreeNode(min(arr))
    queue = [root]
    i = 0
    while i < len(arr):
        node = queue.pop(0)
        if arr[i] < node.val:
            node.left = TreeNode(arr[i])
            queue.append(node.left)
        else:
            node.right = TreeNode(arr[i])
            queue.append(node.right)
        i += 1
    
    # 中序遍历二叉搜索树，将节点的值依次插入到已排序数组中
    res = []
    stack = []
    while queue:
        node = queue.pop(0)
        if stack:
            parent = stack[-1]
            if parent.val > node.val:
                while stack and stack[-1].val > node.val:
                    res.append(stack.pop())
                parent.right = node
                node.left = parent
            else:
                parent.left = node
                node.right = parent
        stack.append(node)
    while stack:
        res.append(stack.pop())
    return res[::-1]  # 返回已排序数组，由于是中序遍历，因此需要反转结果数组