using System;

using System.Collections.Generic;

​

public class Node

{

    public int Value { get; set; }

​

    public Node Left { get; set; }

​

    public Node Right { get; set; }

​

    public Node(int value, Node left, Node right)

    {

        Value = value;

        Left = left;

        Right = right;

    }

}

​

public class BinarySearchTree

{

    public static bool Contains(Node root, int value)

    {

        List<int> treeValues = new List<int>(); 

        return FlattenTree(root, ref treeValues).Contains(value);

    }

​

    public static void Main(string[] args)

    {

        Node n1 = new Node(1, null, null);

        Node n3 = new Node(3, null, null);

        Node n2 = new Node(2, n1, n3);

​

        Console.WriteLine(Contains(n2, 3));

    }

​

​

    private static List<int> FlattenTree(Node root, ref List<int> treeValues)

    {

        if (root == null) return treeValues;

​

        Console.WriteLine(root.Value);

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        treeValues.Add(root.Value);

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        FlattenTree(root.Left,  ref treeValues);

        FlattenTree(root.Right, ref treeValues);

​

        return treeValues;

​

    }

}