CS 1332 Homework 3: Stacks and Queues

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Stacks and Queues
You are to code the following:
1. A stack backed by a linked list
2. A stack backed by an array
3. A queue backed by a linked list
4. A queue backed by an array
A queue is a first-in, first-out (FIFO) data structure. A stack is a last-in, first-out (LIFO) data
structure.
All of your data structures should implement the appropriate interface, either QueueInterface or
StackInterface. Both interfaces define an initial capacity that you must use in your array implementations; make sure to use the provided variable, not a magic number. Your linked list implementations
should use the given head (and tail) pointer(s) to build the backing structure. Do NOT use Java’s linked
list classes.
As always, these implementations must be as efficient as possible. Failure to do so will result in
large point deductions.
Circular Arrays
The backing array in your ArrayQueue implementation must behave circularly. This means that when
the user dequeues an element, you should simply treat the next index in the array as the new front.
DO NOT SHIFT ANY ELEMENTS IN THE ARRAY. This also means that if there are empty
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Homework 3: Stacks and Queues Due: See T-Square
spaces at the front of the array, the back of the queue should wrap around to the front of the array and
make use of those spaces.
When regrowing the backing array, realign the queue with the front of the new array during transfer,
so that the front of the queue is once again at index 0. This is the ONLY time that the front of the
queue should be reset. When dequeueing the last element in the queue, simply increment front as you
normally would and leave it there.
A note on JUnits
We have provided a very basic set of tests for your code, in StacksQueuesStudentTests.java. These
tests do not guarantee the correctness of your code (by any measure), nor does it guarantee you any
grade. You may additionally post your own set of tests for others to use on the Georgia Tech GitHub as
a gist. Do NOT post your tests on the public GitHub. There will be a link to the Georgia Tech GitHub
as well as a list of JUnits other students have posted on the class Piazza.
If you need help on running JUnits, there is a guide, available on T-Square under Resources, to help
you run JUnits on the command line or in IntelliJ.
Style and Formatting
It is important that your code is not only functional but is also written clearly and with good style. We
will be checking your code against a style checker that we are providing. It is located in T-Square, under
Resources, along with instructions on how to use it. We will take off a point for every style error that
occurs. If you feel like what you wrote is in accordance with good style but still sets off the style checker
please email Carey MacDonald (careyjmac@gatech.edu) with the subject header of “CheckStyle XML”.
Javadocs
Javadoc any helper methods you create in a style similar to the existing Javadocs. If a method is
overridden or implemented from a superclass or an interface, you may use @Override instead of writing
Javadocs. Any Javadocs you write must be useful and describe the contract, parameters, and return
value of the method; random or useless javadocs added only to appease Checkstyle will lose points.
Exceptions
When throwing exceptions, you must include a message by passing in a String as a parameter. The message must be useful and tell the user what went wrong. “Error”, “BAD THING HAPPENED”,
and “fail” are not good messages. The name of the exception itself is not a good message.
For example:
throw new PDFReadException(“Did not read PDF, will lose points.”);
throw new IllegalArgumentException(“Cannot insert null data into data structure.”);
Generics
If available, use the generic type of the class; do not use the raw type of the class. For example, use new
LinkedList() instead of new LinkedList(). Using the raw type of the class will result in a
penalty.
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Homework 3: Stacks and Queues Due: See T-Square
Forbidden Statements
You may not use these in your code at any time in CS 1332.
• break may only be used in switch-case statements
• continue
• package
• System.arraycopy()
• clone()
• assert()
• Arrays class
• Array class
• Collections class
• Collection.toArray()
• Reflection APIs
• Inner or nested classes
Debug print statements are fine, but nothing should be printed when we run your code. We expect
clean runs – printing to the console when we’re grading will result in a penalty. If you submit these, we
will take off points.
Provided
The following file(s) have been provided to you.
1. ArrayQueue.java
This is the class in which you will implement the array-backed queue. Feel free to add private
helper methods but do not add any new public methods, inner/nested classes, instance
variables, or static variables.
2. ArrayStack.java
This is the class in which you will implement the array-backed stack. Feel free to add private
helper methods but do not add any new public methods, inner/nested classes, instance
variables, or static variables.
3. LinkedNode.java
This class represents a single node in the linked list. It encapsulates data and the next reference.
Do not alter this file.
4. LinkedQueue.java
This is the class in which you will implement the linked list-backed queue. Feel free to add private
helper methods but do not add any new public methods, inner/nested classes, instance
variables, or static variables.
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Homework 3: Stacks and Queues Due: See T-Square
5. LinkedStack.java
This is the class in which you will implement the linked list-backed stack. Feel free to add private
helper methods but do not add any new public methods, inner/nested classes, instance
variables, or static variables.
6. QueueInterface.java
This is one of the interfaces you will implement. All instructions for what the methods should do
are in the javadocs. Do not alter this file.
7. StackInterface.java
This is one of the interfaces you will implement. All instructions for what the methods should do
are in the javadocs. Do not alter this file.
8. StacksQueuesStudentTests.java
This is the test class that contains a set of tests covering the basic operations of your implementations. It is not intended to be exhaustive and does not guarantee any type of grade. Write your
own tests to ensure you cover all edge cases.
Deliverables
You must submit all of the following file(s). Please make sure the filename matches the filename(s)
below. Be sure you receive the confirmation email from T-Square, and then download your uploaded
files to a new folder, copy over the interfaces, recompile, and run. It is your responsibility to re-test your
submission and discover editing oddities, upload issues, etc.
1. ArrayQueue.java
2. ArrayStack.java
3. LinkedQueue.java
4. LinkedStack.java
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