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){..........}
}

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);
}
}
}