1676. Lowest Common Ancestor of a Binary Tree IV

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None


class Solution:
    def lowestCommonAncestor(
        self, root: 'TreeNode', nodes: 'List[TreeNode]'
    ) -> 'TreeNode':
        def dfs(root):
            if root is None or root.val in s:
                return root
            left, right = dfs(root.left), dfs(root.right)
            if left and right:
                return root
            return left or right

        s = {node.val for node in nodes}
        return dfs(root)