# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def delNodes(self, root: TreeNode, to_delete: List[int]) -> List[TreeNode]:
        #TC: O(nodes)
        #SC: O(max depth)

        #trick to use RETURN and FLAG 

        to_delete = set(to_delete)
        res = []

        def help(root, isRoot):
            if not root:
                return None

            if root.val not in to_delete:
                if isRoot:
                    res.append(root)

                root.left = help(root.left, False)
                root.right = help(root.right, False)
                return root
            else:
                help(root.left, True)
                help(root.right, True)
                return None

        help(root, True)
        return res

算法2

(暴力枚举) $O(n^2)$

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时间复杂度

参考文献

C++ 代码

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