Solved

ADT's

Posted on 1997-06-15
1
198 Views
Last Modified: 2010-04-16
Please could anyone can help with this apparantly easy question on ADT's


The generic ADT named DIRECTORY(NI), where NI represents any ADT having a NAME operation returning a STRING. An example of NI is the ADT PERSON that has an operation called NAME which returns the name of a person as an instance of type STRING. The operations of the generic directory are as follows:-
CREATEDIR - creates an empty directory.
RETRIEVE - takes a directory and a name(i.e a string) as source and returns an item of NI as its result.
ADD - takes a directory and an item of NI and returns the directory with that item added.
ISINDIR - takes a directory and a name and returns TRUE if an item with that name is in the directory.
COUNT - takes a directory and return the number of items in that directory.

{THE QUESTION}

Using the constructive approach, write down the semantics of the RETRIEVE and COUNT operations.  Use the ADT BSTree as an underlying model.
0
Comment
Question by:dave1
1 Comment
 

Accepted Solution

by:
kev45 earned 50 total points
ID: 1215380
If I understand your question correctly, NI is a node on a binary tree as follows:

TYPE
  NIptr = ^NIType;
  NIType = RECORD
             Left : ^NIType;
             Right : ^NIType;
             Data : string;    {I'm assuming Turbo Pascal}
           END;
VAR
  NI : NIType;
  DIRECTORY : NIptr;

with a function name as follows:
FUNCTION NAME(N : string) : string;
BEGIN
  NAME := NI.Data;
END;

Therefore Directory's Retrieve would be as follows:

FUNCTION RETRIEVE(N : string) : NIType;
VAR
  Tmp : NIType;

BEGIN
  Tmp.Left := nil;
  Tmp.Right := nil;
  Tmp.Data := N;
  RETRIEVE := Tmp;
END;

And count would be as follows:

FUNCTION Count (D : ^NIType) : integer; {or longint if many nodes}
BEGIN
  IF (D.left = nil) AND (D.right = nil) THEN
    Count := 1
  ELSE
    IF (D.left = nil) THEN
      Count := Count(D.right) + 1
    ELSE
      IF (D.right = nil) THEN
         Count := Count(D.left) + 1
      ELSE
         Count := Count(D.left) + Count(D.right) + 1;
END;  

Kevin
0

Featured Post

Secure Your Active Directory - April 20, 2017

Active Directory plays a critical role in your company’s IT infrastructure and keeping it secure in today’s hacker-infested world is a must.
Microsoft published 300+ pages of guidance, but who has the time, money, and resources to implement? Register now to find an easier way.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Azure Functions is a solution for easily running small pieces of code, or "functions," in the cloud. This article shows how to create one of these functions to write directly to Azure Table Storage.
Arrow Electronics was searching for a KVM  (Keyboard/Video/Mouse) switch that could display on one single monitor the current status of all units being tested on the rack.
In an interesting question (https://www.experts-exchange.com/questions/29008360/) here at Experts Exchange, a member asked how to split a single image into multiple images. The primary usage for this is to place many photographs on a flatbed scanner…

713 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question