CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 1 of 9
Assignment 2 (20% of total marks)
Due date: 15 February 2024, Thursday
Scope:
The tasks of this assignment cover the data structure and algorithm. The assignment
covers the topics discussed in topics 3 and 4.
The assignment is divided into two parts – Part One covers the theoretical aspect of the
materials discussed during classes, and Part Two covers the practicality of the concepts.
The total mark for Part One is 75, and Part Two is 25.
Assessment criteria:
Marks will be awarded for:
Correct,
Comprehensive, and
Appropriate
application of the materials covered in this subject.
Marks:
Total mark: 100
Weightage: 20% of total subject mark
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 2 of 9
Assignment Specification:
Part A: (75 marks)
Question 1 (25 marks)
a. The INORDER traversal output of a binary tree is A,B,N,O,R,M,A,L,L,Y and the
PREORDER traversal output of the same tree is Y,N,A,B,M,O,R,L,A,L. Construct the
tree and determine the output of the POSTORDER traversal output. (6.0 marks)
b. Given the following undirected graph:
Represent the graph as:
(i) Adjacency matrix (3.0 marks)
(ii) Adjacency list (3.0 marks)
(iii) Incidence matrix (3.0 marks)
c. Starting with an empty 2-4 tree, construct a 2-4 tree with the following keys. Show
the major working steps.
14, 12, 11, 13, 16, 15
(10.0 marks)
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 3 of 9
Question 2 (25 marks)
Do a dry run on the two algorithms (ALGORITHM 1 and ALGORITHM 2) shown
below.
ALGORITHM 1
End of function A2
Note: the function ENQUEUE only inserts a new element in the
queue if this element is different from NULL.
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 4 of 9
a) Briefly explain what the purposes of the two algorithms are and state the
asymptotic run-time complexity of each of the algorithms.
b) For the following Binary Search Tree (BST):
What is returned by the function call A1(root)?
(5.0 marks)
c) For the Binary Search Tree (BST) in part (b), provide a detail analysis on
the run-time complexity of the ALGORITHM 2, as explained in lecture.(5.0
marks)
d) Re-write the function A2, in pseudocode, using recursive function calls. You
may not use any form of iteration. (10.0 marks)
e) For a general Binary Search Tree (BST) of N elements, which of the two
algorithms A1 and A2, should you use? Give your choice and explain your
reasoning. (5.0 marks)
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 5 of 9
Question 3 (25 marks)
The data structure shown in Figure 1 depicts an implementation of a list of two
lists, that is, two linked list joined into one. In this example, the data structure is
implemented to group two separate lists of numbers, one consists of lists of even
numbers and the other consists of lists of odd numbers.
Two types of linked list are used in the above implementation. The node of the
main list (highlighted in grey) consists of a content field, a next node field, and a
next list field. The content node holds a value 0 for an odd list and a value 1 for
an even list. The node also contains two reference fields. The first is a ‘next node’
that links to the first node of a secondary list, and the second is a ‘next list’ that
links to the next link list.
The node of the secondary list (non-highlighted) consists of a content field and a
next node field. For an even list, the content holds an even number and for an
odd list, the content holds an odd number. The node has a ‘next node’ field that
link it to the next secondary list node.
Next Node
Next List
head
Next List
Next Node
Node from main list: Node from secondary list:
Next Node
Figure 1: A list of two lists
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 6 of 9
In a single linked list implemented in Java, this is the definition of a node:
class Node {
int data;
Node nextNode;
// Constructor to create a new node
// nextNode is by default initialized as null
Node(int d) { data = d; }
}
a) Assuming that the above definition is kept for the nodes of the secondary
lists, device a new definition of node for the nodes of the main list. Call this
type of node MainNode and use the names of pointers NextNode and NextList
respectively in your implementation. (5.0 marks)
b) Write the pseudocode of the function INSERT(head,x) that inserts a new
number in this data structure. If the number is even it must go to the second
secondary list, the list that starts with node 1 in the main list. Otherwise, it
must go to the first secondary list. Assume the data structure already has
the main list created and numbers are inserted at the start of the secondary
list. (5.0 marks)
c) Write the pseudocode of the function SEARCH(head,x) that returns TRUE if
the number x is in the data structure (in any of the secondary lists) and
FALSE otherwise. (5.0 marks)
d) Write the pseudocode of the function DELETE(head, b) that receives as input
arguments the head of the last of two lists and a Boolean value. The function
DELETE(head,b) deletes one of the main nodes. If b equals 0, then the node
storing number 0 is deleted. Otherwise, the main node storing number 1 is
deleted. Consider the following cases: the main list is empty and it has only
one node (node 0 or 1). (10.0 marks)
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 7 of 9
Part B: (25.0 marks)
Your task for this assignment is to investigate some of the properties of queues.
You should write a Java, C++, or Phyton program which simulates the queuing
system in an email server.
Queues are commonly used in network systems. For example, e-mail is placed in
queues while it is waiting to be sent and after it arrives at the recipient’s mailbox.
A problem occurs, however, if the outgoing mail processor cannot send one or
more of the messages in the queue. For example, a message might not be sent
because the recipient’s system is not available.
Write an e-mail simulator that processes mail at an average of 20 messages per
minute. As messages are received, they are placed in a queue. For the simulation,
assume that the messages arrive at an average rate of 30 messages per minute.
Remember, the messages must arrive randomly, so you will need to use a random
number generator to determine when messages are received.
Each minute, you can dequeue up to 20 messages and send them. Assume that
up to 25% of the messages in the queue cannot be sent in any processing cycle.
Again, you will need to use a random number to determine whether a given
message can be sent. If it cannot be sent, put it back at the end of the queue or
enqueue it.
Run the simulator for 15 minutes, tracking the number of times each message
had to be requeued. At the end of the simulation, print the statistics that show:
1 The total messages processed.
2 The average arrival rate, that is, the average number of messages arriving
per minute.
3 The average number of messages sent per minute.
4 The average number of messages in the queue in a minute.
5 The number of messages sent on the first attempt, the number of messages
sent on the second attempt, and so forth.
6 The average number of times messages had to be requeued (do not include
the messages sent the first time in this average.)
NOTE: Since the question is to assess your understanding of the concept of
Queue, you are NOT allowed to use the library of the language that implement
queue. You need to write the codes (implementation) of Queue for this exercise.
(See point (iii).)
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 8 of 9
Sample Output:
Please enter the total minutes to run: 30
Total number of messages processed : 565
Average arrival rate : 29.60
Average number of messages sent per minute : 28.7
Average number of messages in the queue per minute : 65.07
Number of messages sent on 1st attempt : **
Number of messages sent on 2nd attempt : 87
Number of messages sent on 3rd attempt : 18
Number of messages sent on 4th attempt : 4
Number of messages sent on 5th attempt : 2
Average number of times messages had to be requeued : 1.30
Note: These are just sample answers to show the output format required from
your program. They are NOT necessarily the output that your program must
produce because the numbers shown were randomly generated.
Standard Requirements for Part B (Programming question):
(i) Java Version – JDK 6 update 17 or higher (Using Windows), or
(ii) C++ / C compiler – g++ 4.0 or higher (Using Windows or UBUNTU). In the event
that you use UBUNTU via VM, be careful with the memory function of the language
and make sure that the functions are used properly and do not cause any
segmentation error when the codes are compiled in Windows environment.
(iii) All coding must be your own work. Standard libraries of data structures and
algorithms such as STL may not be used.
(iv) Programs should be appropriately documented with comments.
(v) Execute your program and screen-capture the output. Include in your submission
all source code and libraries plus the screen-captures.
(vi) Students are to place all compilation and instructions on how to run the program
inside a readme.txt file. Your lecturer will refer to this file when marking. Without
a readme.txt or clear instructions for compilation, your lecturer will compile based
on his/her computer setting; any incompatibility, will deem as failure to compile
the program.
(vii) Submission filenames are to follow the naming convention given in the submission
instruction below. Do not use your own filename.
School of Computing and Information Technology University of Wollongong
CSCI203 – Data Structures and Algorithm, 2024 S1
SCIT, University of Wollongong, copyright 2024
Page 9 of 9
Submissions
This assignment is due by 9:00 pm Singapore time on Thursday, 15 February 2024.
For Part A, type or hand-written your answer for each question in a MS Word or
equivalent document format and save it in a pdf formatted file, name your file as
YourUOWStudentNumber-A2-SolPartA.pdf.
For Part B, the name of your program should be QueueSim.cpp, QueueSim.java, or
QueueSim.py depending on the programming language that you use to develop
your program. Execute your program and screen capture your output. Next, zip
your source code, libraries, readme.txt together with your screen capture and name
your file as YourUOWStudentNumber-A2-SolPartB.zip.
Zip together YourUOWStudentNumber-A2-SolPartA.pdf and
YourUOWStudentNumber-A2-SolPartB.zip and name your file as
YourUOWStudentNumber-A2.zip. Do not use your own filename.
All assignments that do not satisfy the submission requirements listed above will
not be evaluated and will be returned to the students with 0 marks.
Submit the files YourUOWStudentNumber-A2.zip through Moodle in the following
way:
1) Access Moodle at http://moodle.uowplatform.edu.au/
2) To login use a Login link located in the right upper corner the Web page or in
the middle of the bottom of the Web page
3) When successfully logged in, select a site CSCI203 (SP124) Algorithms and
Data Structures
4) Scroll down to a section Submissions of Assignments
5) Click at Submit your Assignment 2 here link.
6) Click at a button Add Submission
7) Move a file, for example, YourUOWStudentNumber-A2.zip into the
submission area. You can drag and drop files here to add them. You can also
use a link Add…
8) Click at a button Save changes,
9) Click at a button Submit assignment,
10) Click at the checkbox with a text attached: By checking this box, I confirm that
this submission is my own work, … in order to confirm authorship of your
submission,
11) Click at a button Continue.
A policy regarding late submissions is included in the subject outline.
Only one submission per student is accepted.
Assignment 2 is an individual assignment, and it is expected that all its tasks will be
solved individually without any cooperation with the other students. Plagiarism is treated
seriously. Students involved will likely receive zero. If you have any doubts, questions,
etc. please consult your lecturer or tutor during lab classes or over e-mail.
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