using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

​

​

class TreeNode

{   

    public Customer Parent; 

    public Customer Customer;   

    public Dictionary<int, TreeNode> Children;

    public TreeNode(Customer cust)

    {

        this.Customer = cust;

    }

​

    public TreeNode(Customer cust, Customer par)

    {

        this.Customer = cust;

        this.Parent = par;

    }

​

    public TreeNode(Customer cust, Customer par, TreeNode[] list)

    {

        this.Customer = cust;

        this.Parent = par;

        foreach(var item in list)

        {

            this.Children.Add(item.Customer.Id, item);

        }       

    }

    public void AddChild(TreeNode[] list)

    {

        foreach(var item in list)

        {

            this.Children.Add(item.Customer.Id, item);

        }

    }

    public void AddChild(TreeNode nd)

    {

        this.Children.Add(nd.Customer.Id, nd);

    }

}

​

class Tree

{

    Dictionary<int, TreeNode> tree;

    public void AddNode(TreeNode parent, TreeNode child)

    {

        if(parent.Parent == null)

        {

            tree.Add(child.Customer.Id, child);

        }

        TreeNode parentNode = FindParentNode(parent, tree);

        parentNode.AddChild(child);

    }

    public TreeNode FindParentNode(TreeNode parent, Dictionary<int, TreeNode> list)

    {

        TreeNode theNode;

        list.TryGetValue(parent.Customer.Id, out theNode);

        if(theNode == null)

        {           

            foreach(var item in tree.Values)

            {

                theNode = FindParentNode(parent, item.Children);

            }

        }

        return theNode;

    }

}

​

class Customer

{

    public int Id {get; set;}

    public string Name {get; set;}

}