CHC5223 Data Structures and Algorithms 2022–2023 Semester 2
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Assignment 2
Value 65% of coursework: Part A is 35% and Part B is 30%
Individual work
Learning outcomes
Students will be able to understand
1.1 Data structures
1.2 The applications of data structures
1.3 Object-oriented programming concepts
1.4 Methods for program testing
Students will have acquired skills in:
2.1 Data abstraction
2.2 The use of data structures
2.3 Programming at a more advanced level in a high-level object-oriented language
2.4 Program testing and documentation
Students will have acquired skills in:
3.1 Self-management
3.2 Learning
3.3 Communication
3.4 Problem solving
3.5 Information technology
Process and what submit to Student Website
The assignment submitted should compressed into a .zip file, the following files should be
contained in the compressed file：
• a report as a Microsoft Word document containing text of all your classes.
filename format: 12345678_CHC5223_CW2_Report.docx
• a .zip file containing the project: the runnable jar file (if available) and all the program’s
source texts (.java), including those provided
filename format: 12345678_CHC5223_ CW2_Files.zip
Part A – binary search tree
General requirements
All your programming must conform to “Java Conventions and Programming Guidelines” – see
module Moodle site.
You must paste the source code of all your classes into your report, as text or images.
Introduction
The topic of this part of the assignment is binary search trees.
The interface IMemberDB describes methods for an abstract data type (ADT) which holds a
database of Member objects.
You must implement IMemberDB as a binary search tree for Assignment 2.
You must not make any changes to these interfaces.
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Requirements
Task 1
You must create a Java class called MemberBST that implements the interface IMemberDB.
You must use a binary search tree but it does not need to be self-balancing.
You must not encapsulate existing implementations of collections in your submission. For
example, you must not create a TreeMap object and call methods on that object from your class.
Failure to comply with this will result in zero marks for that part.
Tip: use String.compareTo to compare strings lexicographically. You can treat uppercase and
lowercase as different. (Hash codes have no place in this assignment.)
Methods can be implemented either iteratively or recursively. You must not implement the
method remove by just building a new tree.
You may make use of the supplied source text for the method remove, based on Object-Oriented
Programming in Oberon-2, Hanspeter Mössenböck Springer-Verlag 1993, page 78, transcribed
into Java by David Lightfoot (see Appendix).
The constructor for MemberBST must print the string “Binary Search Tree” to System.out.
Take care that you have not used a linear search O(n) where you should have used a binary
search tree, aiming towards O(logn).
12 marks
Task 2
You must make appropriate use of assertions (assert statements) to protect preconditions of the
operations. Remember to enable assertion checking for your project.
2 marks
Task 3
You must make your class log monitoring information, either to a text file or by calls of
System.out.println.
It must log (at least):
• for every addition of a Member (put), for every get the Member(get), for every deletion
of a Member(remove):
o the Member name;
o the sequence of nodes of the tree visited.
• Paste your log into your report.
6 marks
We have supplied a main program CHC5223.java for your use with this assignment.
The name of the file is set in the static variable filename.
Sample files sampleMembersUK.csv and sampleMembersUS.csv each contain 500 members in
this format.
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Task 4
You must devise a test plan for your implementation. Be sure to check (among many other
cases).
• that deleting a leaf node works correctly
• that deleting a node with one descendant works correctly
• that deleting a node with two descendants works correctly
5 marks
Task 5
By using the supplied main program, or by other means, you must test your MemberBST.
Include your test plan, test data used, expected results and actual results in your report. You
must show your actual results and the logging information copied from your log file or the
output pane of your IDE. Do not simply state “test passed”, or similar – show evidence
6 marks
Task 6
You must state honestly which of the requirements of Assignment 2 you have successfully
fulfilled, citing evidence. Also, comment on the time efficiency and space efficiency of your
implementation of the binary search tree.
4 marks
total 35 marks
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Part B – graphs and pathfinding
The topic of this part of Assignment 2 is graphs and pathfinding.
General requirements
All your programming must conform to “Java Conventions and Programming Guidelines”.
You must paste the source code of all your classes into your report, as text, not images.
You must implement all necessary data structures using only arrays
When programming in Java it is usual to make use of collection classes from the Java class library.
However, if you need to program in some other language such classes, or their equivalents, will
not necessarily be available.
Task 1
Find or devise a transport network – it need not be real, but it must be realistic. It must be an
undirected, connected graph, with no loops. It must have at least eight nodes.
Each node should have a name (with no spaces in it) and x and y positions (0 x < 256 and
0 y < 256) indicating the approximate position of the node on a map with a 256 × 256 grid (y
increasing downwards).
The links must contain information about the distance between the nodes it connects. The
distance can be measured in suitable units of length, such as km, or time, such as minutes.
The links between them must be such that there are several pairs of nodes that are linked by
more than one route.
You must sketch your network and include it in your report. The sketch must show each node
annotated with its name and located on the sketch at its x and y position. The sketch must show
each link annotated with its distance. You can make the sketch by hand but if you do so you will
need to scan it to include in your report.
2 marks
Task 2
You must express your network as a text file using the syntax:
“station” name x y
“link” station station distance
Each station must have been defined in a station line before being cited in a link line.
Include the content of the text file in your report.
2 marks
Task 3
You must implement Java classes StackInt, QueueInt, ListInt and SetInt. These will be subclasses
respectively of abstract classes AbsStackInt, AbsQueueInt, AbsListInt, AbsSetInt, whose source is
provided and shown in the appendixes. These are given as abstract classes (to be ‘sub-classed’)
rather than as interfaces (to be ‘implemented’) partly because they are all ‘bounded’, that is,
with limited capacity because of being implemented by arrays, and also to allow us to give you
hints on how to implement them.
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The required behaviour of the methods of the classes is indicated as pre- and post-conditions in
comments.
4 marks
Task 4
You must make appropriate use of assertions (assert statements) to protect preconditions of the
operations. Remember to enable assertion checking for your project.
1 mark
Task 5
By using JUnit or otherwise you must test your implementations of StackInt, QueueInt, ListInt
and SetInt. To do this, create objects of each class in which capacity is set to a low value, such as
10. You will set it to something larger when deploying the classes later.
Include your test plan, test data used, expected results and actual results in your report. Your
actual results must be shown either as screen images or as text copied from the output pane of
the development toolkit.
4 marks
Task 6
You must create a Java class StationInfo to implement the Java interface IStationInfo (supplied).
1 mark
Task 7
You must create a Java class to define an adjacency matrix
final double NO_LINK = Double.MAX_VALUE; // was erroneous double.MAX_VALUE
int numStations; // 0 <= numStations <= capacity
double distance[ ][ ];
where, for all i, j in 0 <= numStations <= capacity
distance [i][j] is the distance from station with number i to station with number j
distance [i][j] is equal to distance [j][i]
distance [i][i] = NO_LINK
Task 8
and also define a list of objects of class StationInfo held in an array.
Task 9
You must create a Java method in this class that reads a text file containing the textual
description of your network and builds the corresponding list of stations and the matrix of links.
You must perform as many validity checks in this as you can and report any errors. Include the
text of this class in your report.
2 marks
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Task 10
Use print statements to show the contents of the list and of the matrix after using your program
to build them from the data held in your text file. Copy the results into your report.
2 marks
Task 11
You must write Java methods (as in Appendixes) to perform a depth-first traversal from a given
node of your network and a breadth-first traversal from the same node, making use of the
algorithms given in the appendix. Include the methods text and the resulting sequence of node
names in your report.
4 marks
Task 12
You must implement Dijkstra’s algorithm (as in Appendix) making use of the data structures you
have constructed, to find and display the shortest path between two stations in your network.
You must also ‘instrument’ your implementation to count the number of iterations of the while
loop
4 marks
Task 13
Explain the difference between Dijkstra’s algorithm and A* algorithm and state how their
behaviour would differ in the case of your network.
2 marks
Task 14
Comment on the degree of success you have achieved with each of these tasks.
2 marks
total 30 marks
Obtaining help
It is always permissible to request advice on what is required for this assignment. Please try to
do this during normal contact time and avoid asking for such help in the last week before the
deadline.
You can discuss the requirements and the material covered in the assignment with others but
what you create must be all your own work. Be careful to avoid collusion.
Declare in your report any help you have received other than that from the module teaching
team.
Feedback
In addition to the written feedback that we aim to provide within the normal interval, you will be
able to obtain fast, brief, verbal formative feedback and help on correcting your work at your
practical classes.
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Appendix: remove
private class Node {
private Member data;
private Node left, right;
public Node(Member s) {data = s; left = null; right = null;}
} // Node
private Node root;
public Member remove(String name){
// based on Object-Oriented Programming in Oberon-2
// Hanspeter Mössenböck Springer-Verlag 1993, page 78
// transcribed into Java by David Lightfoot
// put assert statement for preconditions here
Node parent = null, del, p = null, q = null;
Member result;
del = root;
while (del != null && !del.data.getName().equals(name)) {
parent = del;
if (name.compareTo(del.data.getName()) < 0)
del = del.left;
else
del = del.right;
}// del == null || del.data.getName().equals(name))
if(del != null) { // del.data.getName().equals(name)
// find the pointer p to the node to replace del
if (del.right == null) p = del.left;
else if (del.right.left == null) {
p = del.right; p.left = del.left;
} else {
p = del.right;
while (p.left != null) {q = p; p = p.left;}
q.left = p.right; p.left = del.left; p.right = del.right;
}
if(del == root) root = p;
else if (del.data.getName().compareTo(parent.data.getName()) < 0)
parent.left = p;
else parent.right = p;
// reduce size of tree by one
result = del.data;
}
else result = null;
return result;
} // remove
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Appendix Abstract class AbsListInt
package CHC5223; // or whatever
/**
* Abstract class to be sub-classed by class(es) that represent lists of ints
*
* You may change the package name for this, but you should not
* modify it in any other way.
*
*/
abstract public class AbsListInt {
protected int list[];
protected int size; // 0 <= size <= capacity
protected final int capacity;
/**
* @param capacity -- maximum capacity of this list
* @post new list of current size zero has been created
*/
public AbsListInt(int capacity){
// implements a bounded list of int values
this.capacity = capacity;
this.size = 0;
list = new int[capacity];
}
public int getCapacity() {return capacity;}
public int getSize() {return size;}
/**
* @param n node to be added
* @pre getSize() != getCapacity()
* @post n has been appended to list
*/
abstract public void append(int n);
/**
* @param x -- value to be sought
* @pre true
* @return true if x is in list*/
abstract public boolean contains(int x);
}
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Appendix Abstract class AbsQueueInt
package CHC5223; // or whatever
/**
* Abstract class to be sub-classed by class(es) that represent stacks of ints
*
* You may change the package name for this, but you should not
* modify it in any other way.
*
*/
abstract public class AbsQueueInt {
protected int queue[];
protected int size; // 0 <= size <= capacity
protected final int capacity;
public AbsQueueInt(int capacity){
this.capacity = capacity;
this.size = 0;
this.queue = new int[capacity];
}
public int getCapacity() {return capacity;}
public int getSize() {return size;}
/**
* @param n node to be added
* @pre getSize() != getCapacity()
* @post n has been added to back of queue
*/
abstract public void addToBack(int n);
/**
* @pre getSize() != 0
* @post element at front of queue has been removed
* @return value that has been removed */
abstract public int removefromFront();
}
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Appendix Abstract class AbsSetInt
package CHC5223; // or whatever
/**
* Abstract class to be sub-classed by class(es) that represent stacks of ints
*
* You may change the package name for this, but you should not
* modify it in any other way.
*
*/
abstract public class AbsSetInt {
protected int set[];
protected int size; // 0 <= size <= capacity
protected final int capacity;
/**
* @param capacity -- maximum capacity of this queue
* @pre capacity >= 0
* @post new set of current size zero has been created
*/
public AbsSetInt(int capacity){
this.capacity = capacity;
this.size = 0;
this.set = new int[capacity];
}
public int getCapacity() {return capacity;}
public int getSize() {return size;}
/**
* @param x -- value to be sought
* @pre true
* @return true iff x is in list*/
abstract public boolean contains(int x);
/**
* @param n node to be added
* @pre contains(n) || getSize() != getCapacity()
* @post contains(n)
*/
abstract public void include(int n);
/**
* @pre true
* @post !contains(n)
*/
abstract public void exclude(int n);
}
CHC5223 Data Structures and Algorithms 2022–2023 Semester 2
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Appendix Abstract class AbsStackInt
package CHC5223; // or whatever
/**
* Abstract class to be sub-classed by class(es) that represent stacks of ints
*
* You may change the package name for this, but you should not
* modify it in any other way.
*
*/
abstract public class AbsStackInt {
protected int stack[];
protected int size; // 0 <= size <= capacity
protected final int capacity;
/**
* @param capacity -- maximum capacity of this queue
* @pre capacity >= 0
* @post new stack of current size zero has been created
*/
public AbsStackInt(int capacity){
this.capacity = capacity;
this.size = 0;
stack = new int[capacity];
}
public int getCapacity() {return capacity;}
public int getSize() {return size;}
/**
* @param n node to be added
* @pre getSize() != getCapacity()
* @post n has been pushed on to top of stack
*/
abstract public void push(int n);
/**
* @pre getSize() != 0
* @post element on top of stack has been removed
* @return value that has been removed */
abstract public int pop();
/**
* @pre getSize() != 0
* @return value on top of stack */
abstract public int peek() ;
}
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Interface IStationInfo
package CHC5223; // or whatever
/**
* Interface to be implemented by class(es) that represent
* information about stations
*
* You may change the package name for this, but you should not
* modify it in any other way.
*
*/
public interface IStationInfo {
/**
* @return the name of the station
*/
String getName();
/**
* @return x position -- 0 <= getxPos() < 256
*/
int getxPos();
/**
* @return y position -- 0 <= getyPos() < 256
*/
int getyPos();
}
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Appendix: breadth-first traversal, beginning with a specified start station
Let Q be an empty queue of Stations
Let L be an empty list of Stations
Add the start station to the back of Q
while Q is not empty do
Remove the Station at the front of Q, call this Station S
Add S to the end of L
if S is not in list L then
Append S to L
for each station S2 that is adjacent to S do
if S2 is not in the list L then
Add S2 to the back of queue Q
endif
endfor
endif
endwhile
return L
Appendix: depth-first traversal, beginning with a specified start station.
Let S be a stack of Stations
Create an initially empty list of Stations, which we will call L
Push the start station on to the stack S
while S is not empty do
Pop the Station at the top of the stack. Call this Station T.
if T is not already in list L then
add it to the back of that list
endif
for each station T2 that is adjacent to T do
if T2 is not in the list L then
push it on to the top of the stack S
endif
endfor
endwhile
return L
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Appendix: Dijkstra’s algorithm for shortest path in a network
set Closed to be empty
add all nodes in the graph to Open.
set the g-value of Start to 0, and the g-value of all the other nodes to ∞
set previous to be none for all nodes.
while End is not in Closed do
let X be the node in Open that has the lowest g-value (highest priority)
remove X from Open and add it to Closed.
if X is not equal to End then
for each node N that is adjacent to X in the graph, and also in Open do
let g’ = g-value of X + cost of edge from N to X
if g’ is less than the current g-value of N then
change the g-value of N to g’
make N’s previous pointer point to X
endif
endfor
endif
endwhile
reconstruct the shortest path from Start to End by following “previous” pointers to find the
previous node to End, the previous node to that previous node, and so on.