資料結構與演算法(C#實現)系列—樹

 Heavenkiller(原創)

首先我們給樹下一個定義：

樹是一個有限的、非空的結點集，

T={r} or T1 or T2 or…or Tn

它具有下列性質：

1．集合指定的結點r叫做樹的根結點

2．其餘的結點可以劃分成n個子集，T1,T2,…Tn(n>=0),其中每一個子集都是一棵樹。

 

樹的其它定義如度，葉子，高等就請大家查閱別的資料吧，到處都有的。

 

樹的主要性質一個就是遍曆，分為深度遍曆和廣度遍曆

在這裡分別實現為DepthFirstTravesal()和WidthFirstTravesal()

其中深度遍曆又分為前序走訪、中序遍曆、和後序遍曆

這是是採用適配器技術實現的。

 

using System;

using System.Collections;

 

namespace DataStructure

{

     /// <summary>

     /// Tree 的摘要說明。

     /// when traverse, traversaltype can't be changed,or throw a  exception

     /// 支援枚舉、比較、深度複製

     /// </summary>

     public abstract class Tree:IEnumerable,IComparable

     {

         public Tree()

         {

              //

              // TODO: 在此處添加建構函式邏輯

              //

         }

         protected Queue keyqueue=new Queue();//僅僅用於枚舉時存放資料，不參與Equals實現中的比較

         protected TraversalType traversaltype=TraversalType.Breadth;// choose a traversal  type,and  DepthFirst is default

         //protected uint degree=0;//degree of the tree, init  it as 0

         //protected uint height=0;//height of the tree, init it as 0

 

         //枚舉不同的遍曆類型

         public enum TraversalType

         {

              Breadth=1,//廣度遍曆

              PreDepth=2,//前序走訪

              InDepth=3,//中序遍曆

              PostDepth=4//後序遍曆

             

         };

         //public virtual abstract object  Key{}

        

         public abstract Tree this[uint _index]{get;set;}//if I only use get, can I change it later?

 

         public  abstract object Key{get;}

         public  abstract uint Degree{get;}

         //public  abstract uint Height{get;}

         public  void SetTraversalType(TraversalType _type){traversaltype=_type;}//set a traversal a type, if it's not set manually, DepthFirst will be chosen in default

 

         public  abstract bool IsEmpty();// property takes the place of IsEmpty()

         public  abstract bool IsLeaf();

        

         //Only Visit, needn't queue

         public virtual void DepthFirstTraversal(IPrePostVisitor _vis)//middle depthfirst traversal

         {

              //通過_vis使用不同的訪問者來進行前序、後序、中序遍曆

        

        

              if(!IsEmpty())

              {

                   _vis.PreVisit(this.Key);

 

                   if( this.Degree>=1 )

                   {

                       if( this.Degree>=2)

                       {

                            for(uint i=0;i<(this.Degree-1);i++)//

                            {

                                 this[i].DepthFirstTraversal(_vis);//recursive call

                                 //_vis.Visit(this.Key);

                            }

                       }

                       this[this.Degree-1].DepthFirstTraversal(_vis);

                   }

 

                   _vis.PostVisit(this.Key);

              }

             

             

         }

        

         public virtual void BreadthFirstTraversal(IVisitor _vis)//breadth first traversal

         {

              Queue tmpQueue=new Queue();//used to help BreadthFirstTraversal

              //this.keyqueue=new Queue();//store keys

 

              if(!this.IsEmpty())

                   tmpQueue.Enqueue(this);//enqueue the root node at first

              while(tmpQueue.Count!=0)//until the number of the queue is zero

              {

                   Tree headTree=(Tree)tmpQueue.Dequeue();

                   //this.keyqueue.Enqueue(headTree.Key);

                   _vis.Visit(headTree.Key);

                  

                   for(uint i=0;i<headTree.Degree;i++)

                   {

                       Tree childTree=headTree[i];

                       if(!childTree.IsEmpty())

                            tmpQueue.Enqueue(childTree);

                   }

              }

 

         }

        

         //------------------------------------------------end------------------------------------

         //內部成員類 用於提供不同遍曆類型的訪問者

         public class PreOrder:IPrePostVisitor

         {

              private IVisitor visitor;

              public PreOrder(IVisitor _vis){visitor=_vis;}

              #region IPrePostVisitor 成員

 

              public void PreVisit(object _obj)

              {

                   // TODO:  添加 PreOrder.PreVisit 實現

                   this.visitor.Visit(_obj);

              }

 

              public void Visit(object _obj)

              {

                   // TODO:  添加 PreOrder.Visit 實現

              }

 

              public void PostVisit(object _obj)

              {

                   // TODO:  添加 PreOrder.PostVisitor 實現

              }

 

              #endregion

 

         }
資料結構與演算法(C#實現)系列---樹(二)

                    Heavenkiller(原創)

 

         public class InOrder:IPrePostVisitor

         {

              private IVisitor visitor;

              public InOrder(IVisitor _vis){visitor=_vis;}

              #region IPrePostVisitor 成員

 

              public void PreVisit(object _obj)

              {

                   // TODO:  添加 InOrder.PreVisit 實現

              }

 

              public void Visit(object _obj)

              {

                   // TODO:  添加 InOrder.Visit 實現

                   this.visitor.Visit(_obj);

              }

 

              public void PostVisit(object _obj)

              {

                   // TODO:  添加 InOrder.PostVisitor 實現

              }

 

              #endregion

 

          }

         public class PostOrder:IPrePostVisitor

         {

              private IVisitor visitor;

              public PostOrder(IVisitor _vis){visitor=_vis;}

              #region IPrePostVisitor 成員

 

              public void PreVisit(object _obj)

              {

                   // TODO:  添加 PostOrder.PreVisit 實現

              }

 

              public void Visit(object _obj)

              {

                   // TODO:  添加 PostOrder.Visit 實現

              }

 

              public void PostVisit(object _obj)

              {

                   // TODO:  添加 PostOrder.PostVisitor 實現

                   this.visitor.Visit(_obj);

              }

 

              #endregion

 

         }

         protected class EnumVisitor:IVisitor

         {

              Queue thisQueue;

              public EnumVisitor(Queue _que)

              {

                   this.thisQueue=_que;

              }

              #region IVisitor 成員

 

              public void Visit(object _obj)

              {

                   // TODO:  添加 EnumVisitor.Visit 實現

                   this.thisQueue.Enqueue(_obj);

              }

 

              #endregion

         }

 

 

 

 

         #region IEnumerable 成員

 

         public IEnumerator GetEnumerator()

         {

              // TODO:  添加 Tree.GetEnumerator 實現

              EnumVisitor vis=new EnumVisitor(this.keyqueue);

              switch (this.traversaltype)

              {

                   case TraversalType.Breadth:

                       BreadthFirstTraversal(vis);

                        break;

                   case TraversalType.PreDepth:

                       PreOrder preVis=new PreOrder(vis);

                       DepthFirstTraversal(preVis);                      

                       break;

                   case TraversalType.InDepth:

                       InOrder inVis=new InOrder(vis);

                       DepthFirstTraversal(inVis);                   

                       break;

                  case TraversalType.PostDepth:

                       PostOrder postVis=new PostOrder(vis);

                       DepthFirstTraversal(postVis);                     

                       break;

             

                   default:

                       Console.WriteLine("WARNING:please set a travel type first!--void SetTraversalType(TraversalType _type) ");

                       //throw new Exception("WARNING:please set a travel type first!");//if not set a type, a exception will happen

                       break;

              }

              return this.keyqueue.GetEnumerator();

         }

 

         #endregion

資料結構與演算法(C#實現)系列---樹(三)

 Heavenkiller(原創)

 

         //overwrite Object.Equals() ---  reference  type   realization

         public override bool Equals(object _obj)

         {

              if( _obj==null )

                   return false;//因為this不可能為null

              if( ! (this.GetType()==_obj.GetType()) )

                   return false;//類型不相等也不相等

              Tree tmpObj=(Tree)_obj;

              //比較引用成員

              if( !Object.Equals(this.Key,tmpObj.Key) )

                   return false;

             

              //比較實值型別成員

              if( !this.Degree.Equals(tmpObj.Degree) )

                   return false;

              //if( !this.Height.Equals(tmpObj.Height) )

                   //return false;

 

              return true;

         }

         //在此重載 ==,!= 後， 在以後繼承的類中不必實現了

         public static bool operator==(Tree _treeA,Tree _treeB)

         {

              return Object.Equals(_treeA,_treeB);

         }

         public static bool operator!=(Tree _treeA,Tree _treeB)

         {

              return !(_treeA==_treeB);

         }

        

 

    

 

    

    

         #region IComparable 成員

 

         public virtual int CompareTo(object obj)

         {

              // TODO:  添加 Tree.CompareTo 實現

              return 0;

         }

 

         #endregion

    

     }

}