Homework 3: Stacks and Queues Solution

Important




There are general homework guidelines you must always follow. If you fail to follow any of the following guidelines you risk receiving a 0 for the entire assignment.







All submitted code must compile under JDK 8. This includes unused code, so don't submit extra les that don't compile. Any compile errors will result in a 0.



Do not include any package declarations in your classes.



Do not change any existing class headers, constructors, instance/global variables, or method sig-natures.



Do not add additional public methods.



Do not use anything that would trivialize the assignment. (e.g. don't import/use java.util.ArrayList for an Array List assignment. Ask if you are unsure.)



Always be very conscious of e ciency. Even if your method is to be O(n), traversing the structure multiple times is considered ine cient unless that is absolutely required (and that case is extremely rare).



You must submit your source code, the .java les, not the compiled .class les.



After you submit your les, redownload them and run them to make sure they are what you intended to submit. You are responsible if you submit the wrong les.






Stacks and Queues




You are to code the following:







A stack backed by a linked list



A stack backed by an array



A queue backed by a linked list



A queue backed by an array






A queue is a rst-in, rst-out (FIFO) data structure. A stack is a last-in, rst-out (LIFO) data structure.




All of your data structures should implement the appropriate interface, either QueueInterface or StackInterface. Both interfaces de ne an initial capacity that you must use in your array implemen-tations; 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 e cient as possible. Failure to do so will result in large point deductions.




Circular Arrays




The backing array in your ArrayQueue implementation must behave circularly. For this assignment, the front variable in ArrayQueue should represent the index that holds the next element to dequeue. Failure to adhere to this may result in large penalties.







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Homework 3: Stacks and Queues Due: See T-Square










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 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.




Additionally, when removing the last element in the queue, reset the front variable to the beginning of the array, index 0.




Grading




Here is the grading breakdown for the assignment:




Methods:






ArrayQueue enqueue
12pts




ArrayQueue dequeue
9pts




ArrayQueue peek
2pts




LinkedQueue enqueue
8pts




LinkedQueue dequeue
8pts




LinkedQueue peek
2pts




ArrayStack push
10pts




ArrayStack pop
8pts




ArrayStack peek
2pts




LinkedStack push
6pts




LinkedStack pop
6pts




LinkedStack peek
2pts




Other:






Checkstyle
10pts




E ciency
15pts




Total:
100pts







Keep in mind that some functions are dependent on others to work, such as remove methods requiring the add methods to work. Also, the size function is used many times throughout the tests, so if the size isn't updated correctly, many tests can fail.




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 o a point for every style error that occurs. If you feel like what you wrote is in accordance with good style but still sets o the style checker







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Homework 3: Stacks and Queues Due: See T-Square










please email Raymond Ortiz (rortiz9@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 mes-sage 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:




Bad: throw new IndexOutOfBoundsException("Index is out of bounds.");




Good: 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<Integer() instead of new LinkedList(). Using the raw type of the class will result in a penalty.




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()




Re ection APIs




Inner or nested classes Lambda Expressions Method References




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Homework 3: Stacks and Queues Due: See T-Square










If you're not sure on whether you can use something, and it's not mentioned here or anywhere else in the homework les, just ask.




Debug print statements are ne, 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 o points.




Provided




The following le(s) have been provided to you.




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.




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.




LinkedNode.java



This class represents a single node in the linked list. It encapsulates data and the next reference. Do not alter this le.




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.




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.




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 le.




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 le.




StacksQueuesStudentTests.java



This is the test class that contains a set of tests covering the basic operations of your implementa-tions. 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 le(s). Please make sure the lename matches the lename(s) below. Be sure you receive the con rmation email from T-Square, and then download your uploaded les 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.







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Homework 3: Stacks and Queues Due: See T-Square










ArrayQueue.java



ArrayStack.java



LinkedQueue.java



LinkedStack.java

















































































































































































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