# Definition for a binary tree node.

# class TreeNode:

#     def __init__(self, x):

#         self.val = x

#         self.left = None

#         self.right = None

class Solution:

    def findTarget(self, root: TreeNode, k: int) -> bool:

        #先中序遍历 得到一个列表

        tree_list = []

        def inOrder(root):

            if root == None:

                return None

            inOrder(root.left)

            tree_list.append(root.val)

            inOrder(root.right)

        inOrder(root)

        #双指针

        i = 0

        j = len(tree_list)-1

        while(i<j):

            if (tree_list[i]+tree_list[j] == k):

                return True

            elif (tree_list[i]+tree_list[j] < k):

                i += 1

            else:

                j -= 1

        return False