数据结构与算法(C#实现)系列---N叉树

N叉树的每一节点度数都相同，为N

using System;
using System.Collections;
namespace DataStructure

{

     /**//// <summary>

     /// NaryTree 的摘要说明。-----N叉树

     /// </summary>

     public class NaryTree:Tree

     {

         // member variables

         protected object key;

         protected uint degree;

         protected ArrayList treeList=new ArrayList();

         //protected uint height=0;//暂时默认为0

 

         //create an empty tree whose attribute of degree is _degree

         public NaryTree(uint _degree)

         {

              //

              // TODO: 在此处添加构造函数逻辑

              //

              this.key=null;

              this.degree=_degree;

              this.treeList=null;

         }

         //构造一棵叶子结点的N叉树

         public NaryTree(uint _degree,object _key)

         {

              this.key=_key;

              this.degree=_degree;

              this.treeList=new ArrayList();

              this.treeList.Capacity=(int)_degree;

 

              for(int i=0;i<this.treeList.Capacity;i++)

              {

                   

                   this.treeList.Add( this.GetEmptyInstance(_degree) );

              }

         }

         //-----------------------------------------------------------------

         protected virtual object GetEmptyInstance(uint _degree)

         {    return new NaryTree(_degree); }

         //-------------------------------------------------------------------

         //judge whether the tree is an empty tree

         public override bool IsEmpty()

         {    return this.key==null; }

         //判定是否是叶子结点。如果即不是空树且每一棵子树均为空树，则为叶子结点

         public override bool IsLeaf()

         {

              if(IsEmpty())

                   return false;

              for(uint i=0;i<this.degree;i++)

              {

                   if(  !(this[i].IsEmpty()) )

                       return false;

              }

              return true;

         }

         //-----------------------------------Inherited Attributes---------------------------------

         public override object Key

         {

              get

              {

                   return this.key;

              }

         }

         //索引器

         public override Tree this[uint _index]

         {

              get

              {

                   if( _index>=this.degree )

                       throw new Exception("My:out of index!");//如果出界，则抛出异常

                   if( this.IsEmpty() )

                       return null;//如果是空树，则索引器返回一个 null

                   return (Tree)this.treeList[(int)_index];

              }

              set

              {

                   this.treeList[(int)_index]=value;

              }

         }
         public override uint Degree
         {

             get
             {

                 return this.degree;

             }

         }


         //只用于空树结点

         public virtual void AttachKey(object _obj)
         {

             if (!IsEmpty())

                 throw new Exception("My:this node must be a empty tree node!");

             this.key = _obj;

             this.treeList = new ArrayList();//产生一个degree长的数组,并将其初始化为空树

             this.treeList.Capacity = (int)this.degree;



             for (int i = 0; i < this.degree; i++)
             {

                 treeList.Add(new NaryTree(this.degree));

             }

             /**//*

             foreach(object tmpObj in this.treeList)

             {

                  tmpObj=new NaryTree(this.degree);

             }

             */

         }

         //只用于叶子结点，将叶子结点变为一个空结点，并返回叶子结点关键字的引用

         public virtual object DetachKey()
         {

             if (!IsLeaf())

                 throw new Exception("My:this node must be a leaf node!");

             object result = this.key;//store this leaf node temporary

             this.key = null;

             this.treeList = null;


             return result;

         }

         //将子树连接到指定树的第num个结点上，前提是这个结点必须是空结点,并且度数相同，否则抛出异常

         public virtual void AttachSubtree(uint num, NaryTree _naryTree)
         {

             if (this.IsEmpty())

                 throw new Exception("My:it can't be a empty tree!");

             if (!(this[num - 1].IsEmpty()) | this.degree != _naryTree.degree)

                 throw new Exception("My:this[i-1] must be empty and they should have the same degree!");

             this[num - 1] = _naryTree;

         }

         //仅为非空树定义，从给定树中删去它的第i棵子树并连上一个空树,度数相同，并且返回删除的子树引用

         public virtual NaryTree DetachSubtree(uint num)
         {

             if (IsEmpty())

                 throw new Exception("My:it can't be empty! ");

             NaryTree tmpTree = this;

             ((NaryTree)this[num - 1]).key = null;

             ((NaryTree)this[num - 1]).treeList = null;


             return this;

         }

     }

 }