using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Tree t = new Tree();

        t.Root = new TreeNode(1);

        t.Root.Left = new TreeNode(2);

        t.Root.Right = new TreeNode(3);

        t.Root.Left.Left = new TreeNode(4);

        t.Root.Left.Right = new TreeNode(5);

        //t.Root.Left.Left.Left = new TreeNode(6);

        Tree t2 = new Tree();

        t2.Root = new TreeNode(1);

        t2.Root.Left = new TreeNode(2);

        t2.Root.Left.Left = new TreeNode(3);

        //t2.Root.Right = new TreeNode(5);

        Tree t3 = new Tree();

        t3.Root = new TreeNode(1);

        t3.Root.Left = new TreeNode(2);

        t3.Root.Left.Left = new TreeNode(3);

        t3.Root.Left.Left.Left = new TreeNode(3);

        t3.Root.Right = new TreeNode(2);

        t3.Root.Right.Right = new TreeNode(3);

        t3.Root.Right.Right.Right = new TreeNode(3);

        Console.WriteLine("T:" + t.Serialize());

        Console.WriteLine("T2:" + t2.Serialize());

        Console.WriteLine("T3:" + t3.Serialize());

    }

}

​

public class TreeNode

{

    public int value;

    public TreeNode Left = null;

    public TreeNode Right = null;

​

    public TreeNode(int val)

    {

        value = val;

    }

}

​

public class Tree

{

    public TreeNode Root;

​

    public string Serialize()

    {

        Queue<TreeNode> q = new Queue<TreeNode>();

        List<string> res = new List<string>();

        TreeNode tmp;

        q.Enqueue(Root);

​

        while (q.Count > 0)

        {

            tmp = q.Dequeue();

​

            if (tmp == null)

            {

                res.Add("#");

            }

            else

            {

                res.Add(tmp.value.ToString());

                q.Enqueue(tmp.Left);

                q.Enqueue(tmp.Right);

            }

        }

        return string.Join(",", res);

    }

}