Re: Please help for a LinkBinaryTreeInJava

From:
Lew <lew@lewscanon.com>
Newsgroups:
comp.lang.java.help
Date:
Sun, 16 Mar 2008 15:38:41 -0400
Message-ID:
<2JadnT1aGrfc6kDanZ2dnUVZ_oSunZ2d@comcast.com>
Basanta wrote:

I am new in this group,I don't know how far it would help me.
I tried to make a linked based binary tree following the book "data
structures and algorithms in java" By goodRich and tamassia.I did all
but I wanted to implement a function to determine whether a particular
node exists or not.All I want to implement a function boolean
exists(node n).Can anyone help??My program is as follows:-

import java.io.*;

interface Node {
        Object getData();
        int getID();
               }


A generic approach (as a matter of style I include the redundant 'public' in
interface declarations):

  interface Node <T>
  {
   T getData();
   Integer getId(); // could parameterize ID type
  }

class LinkBinTree {
      BinNode root;
      int size;
      LinkBinTree(Object O) {
          root = new BinNode(0);
                            }


Avoid exorbitant indentation. Up to four spaces per level will suffice.

   class BinNode <T> implements Node <T>

{

     T data;
     Integer id;

            BinNode left;
            BinNode right;


     public BinNode( Integer iden )

  {
            id = iden;
            left = null;
            right = null;
            data = null;


You don't need to set things to null again.

                         }

       BinNode(Object O) {

Why do you have this constructor?

Parameters should have names that start with a lower-case letter: 'o', not 'O'.

            id = 0;
            left = null;
            right = null;
            data = null;


You don't need to set things to null or zero again.

                        }


    public T getData() {return data;}

       public int getID() { return id;}

        void addLeft( T obj ) {
             BinNode b = new BinNode(obj);
             left = b;


You don't need 'b':

     left = new BinNode( obj );

                                  }

        void addRight( T obj ) {
             BinNode r = new BinNode(obj);
             right = r;
                                  }


       public

      BinNode <T> addLeft(Node <T> n, T o ) // lower-case 'o'!

            throws TreeEmptyException

    {
             if(!exists(n))

// braces please:
                {
                  throw new TreeEmptyException("Tree doesn't

exists");


//"Tree doesn't exist"

                }

             return n.addLeft( o );
}


       public

      BinNode <T> addRight( Node <T> n, T o ) throws TreeEmptyException{
    if(!exists(n)) throw new TreeEmptyException("Tree doesn't
exists");
            return n.addRight(O);
}

      void preOrder(Node n) {
              LinkQueueApp<Integer> q =new LinkQueueApp<Integer>();
              int p=n.getID();
              q.enqueue(p);
              while(!q.isEmpty()) {
                    p =q.dequeue();
                    System.out.println("The pre-order is : "
+n.getData());
                    for(int i=p;(i==p+1) || (i==p+2)&&i<=size;i++)
                        q.enqueue(i);
                                  }

}

 void boolean exists( Node <T> n ) {
         if(Node == root) return;


You don't show a variable 'root'.

         else {
            if(Node


Are you searching for a certain Node, or a Node with a certain value?

  public static void boolean exists( BinNode <T> root, T value )
  {
   if ( root == null )
   { return false; }
   return (root.value == null? value == null : root.value.equals( value ))
       || exists( root.left, value ) || exists( root.right, value );
  }

--
Lew

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