算法题,不用递归,构造树型

刚发了今天上午的面试题,最后一道算法题,我又看了一下,貌似真不太好实现,要在一个方法中构造整颗树,还不能使用递归.我先把自己的实现发上来,希望能起来抛砖引玉的作用.
8.算法题.
表结构:
ID        ParentID      Text
1          NULL           Root
2          1                 A1
3           1                A2
4           2                B
5           4                C
把以下程序补充完整.
public class TreeNode{.........}
public class Test
{
    public TreeNode LoadTreeNodeFromDatabase(string connectionString){.......}
    /*********************
输出结果如下:
Root
-A1
--B
---C
-A2
   **********************/
public void Print(TreeNode nod){..........}

}

我的实现如下,

using System;
using System.Collections.Generic;
using System.Text;
using System.Reflection;
using System.Data.SqlClient;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            Test t = new Test();
            TreeNode tree = t.LoadTreeNodeFromDatabase("server=.\\SQLExpress;uid=sa;pwd=sa;database=ksl");
            t.Print(tree);
            Console.Read();
        }
    }
    public class TreeNode
    {
        int _ID = 0;
        int _ParentID = 0;
        string _Text = "";
        List<TreeNode> nodes = new List<TreeNode>();

        public TreeNode()
        { }
        public TreeNode(int id, int parentid, string text)
        {
            _ID = id;
            _ParentID = parentid;
            _Text = text;
        }
        public int ID
        {
            get { return _ID; }
            set { _ID = value; }
        }
        public int ParentID
        {
            get { return _ParentID; }
            set { _ParentID = value; }
        }
        public string Text
        {
            get { return _Text; }
            set { _Text = value; }
        }
        public List<TreeNode> Nodes
        {
            get { return nodes; }
        }
    }
    public class Test
    {
        public TreeNode LoadTreeNodeFromDatabase(string connectionString)
        {
            using (SqlConnection conn = new SqlConnection(connectionString))
            {
                SqlCommand cmd = new SqlCommand("SELECT ID,ParentID,Text FROM TblTree", conn);
                conn.Open();
                SqlDataReader reader = cmd.ExecuteReader();
                Dictionary<string, TreeNode> dict = new Dictionary<string, TreeNode>();
                while (reader.Read())
                {
                    int parentID = 0;
                    if (reader["ParentID"] != DBNull.Value)
                        parentID = Convert.ToInt32(reader["ParentID"]);
                    TreeNode node = new TreeNode(Convert.ToInt32(reader["ID"]), parentID, reader["Text"].ToString());
                    dict.Add(node.ID.ToString(), node);
                }
                reader.Close();
                conn.Close();

                TreeNode tree;
                tree = dict["1"];
                foreach (string str in dict.Keys)
                {
                    if (str == "1") continue;
                    TreeNode node = dict[str];
                    TreeNode parentNode = dict[node.ParentID.ToString()];
                    if (parentNode != null)
                        parentNode.Nodes.Add(node);
                }
                return tree;
            }
        }

        /**//***************************************************************
     
         Root
         -A1
         --B
         ---C
         -A2 
          ***************************************************************/
        public void Print(TreeNode node)
        {
            if (node.ParentID != 0)
            {
                for (int i = 0; i < node.ParentID; i++)
                {
                    Console.Write("-");
                }
            }
            Console.WriteLine(node.Text);
            foreach (TreeNode treeNode in node.Nodes)
                Print(treeNode);
        }
    }

}

小奎的石头已经扔出来了...