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...
