C # Building a tree data structure

Transferred from: https://www.jb51.net/article/125747.htm

Tree structure: Recently in the task management, the task can derive the subtasks infinitely and there is no quantitative limit, the front end adopts the Easyui Treegrid tree display control.

A.json Data format:

[  {"    children": [      {        "Children": [         ],        "username": "username2",        "password": "Password2",        "id": "2",        "PId": "1",        "name": "Node 2"      },      {        "Children": [         ],        "username": " UserName2 ",        " password ":" Password2 ",        " id ":" A2 ",        " PId ":" 1 ",        " name ":" Node 2 "      }    ],    "username": "username1",    "password": "Password1",    "id": "1",    "pId": "0",    "name": "Node 1"  }  ]

　　

B. Defining the required fields for an entity

For the versatility of the tree structure, we can define an abstract common entity treeobject to ensure that subsequent list<t> transform tree JSON is involved

Using system;using system.collections.generic;using system.linq;using system.text;using System.Threading.Tasks; namespace mytree.abs{public  class treeobejct  {public    string ID {set; get;}    public string PId {set; get;}    public string name {set; get;}    Public ilist<treeobejct> children = new list<treeobejct> ();    public virtual void Addchildren (treeobejct node)    {      THIS.CHILDREN.ADD (node);}}  }

C. The actual required entity TreeModel Let it inherit treeobject, so that for id,pid,name,children we can apply to other entities, which is also equivalent to our code special contract:

Using mytree.abs;using system;using system.collections.generic;using system.linq;using System.Text;using System.Threading.Tasks; namespace mytree.models{public  class treemodel:treeobejct  {public    string Username {set; get;}    public string Password {set; get;}}  }

　　

2. Recursive traversal

Get all tasks and convert to tree

Getting all tasks into a tree is simpler, we first get the top-level data of pid=0 (that is, a task that does not have a parent), and we recursively traverse their child nodes in turn by the top-level tasks.

///      recursively get data for all tree structures public  ilist<treeobject> GetData ()        {            list<treeobject> nodes = _ Context. Node.where (x = x.parent_node_id = = 0). Select (x=>new treeobject {id=x.id,pid=x.parent_node_id,name=x.name}). ToList ();            foreach (Treeobject item in nodes)            {                Item.children = Getchildrens (item);            }            return nodes;        }        Recursive get child node public        ilist<treeobject> Getchildrens (treeobject node)        {            ilist<treeobject> Childrens = _context. Node.where (c = c.parent_node_id = = node.id). Select (x = new Treeobject {id = x.id, pId = x.parent_node_id, name = X.name}). ToList ();            foreach (Treeobject item in childrens)            {                Item.children = Getchildrens (item);            }            return childrens;        }

3. Non-recursive traversal

Non-recursive traversal does not require the participation of recursive methods in the operation to realize the mosaic of the tree

For the above code, we do not need to modify, only need to define a non-recursive traversal method Notrecursion:

public static void Notrecursion () {  #region non-recursive traversal   System.Diagnostics.Stopwatch SW2 = new System.Diagnostics.Stopwatch ();   SW2. Start ();  dictionary<string, treeobejct> dtomap = new dictionary<string, treeobejct> ();  foreach (var item in models)  {    Dtomap.add (item.id, item);  }  ilist<treeobejct> result = new list<treeobejct> ();  foreach (var item in dtomap.values)  {    if (item.pid = = "0")    {      result. ADD (item);    }    else    {      if (Dtomap.containskey (item.pid))      {        dtomap[item.pid]. Addchilrden (item);   }}} SW2. Stop ();  Console.WriteLine ("----------Non-recursive traversal time:" + SW2. Elapsedmilliseconds + "----------Thread Name:" + T2. Name + ", Thread ID:" + t2. Managedthreadid);   #endregion

Main.cs

private static ilist<treeobejct> models;private static ilist<treeobejct> models2;private static Thread T1; private static Thread t2;static void Main (string[] args) {  int count = 6;  Console.WriteLine ("Number of build tasks:" +count+ "X");  Models = GetData (count);  MODELS2 = GetData (count);  T1 = new Thread (recursion);  t2 = new Thread (notrecursion);  T1. Name = "recursive traversal";  T2. Name = "Non-recursive traversal";  T1. Start ();  T2. Start ();   Console.read ();}

　　

C # Building a tree data structure