[SOLVED] CS1332 Homework 8

Description

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.

1. All submitted code must compile under JDK 8. This includes unused code, so don’t submit extra files that don’t compile. Any compile errors will result in a 0.
2. Do not include any package declarations in your classes.
3. Do not change any existing class headers, constructors, instance/global variables, or method signatures.
4. Do not add additional public methods.
5. Do not use anything that would trivialize the assignment. (e.g. don’t import/use util.ArrayList for an Array List assignment. Ask if you are unsure.)
6. Always be very conscious of efficiency. Even if your method is to be O(n), traversing the structure multiple times is considered inefficient unless that is absolutely required (and that case is extremely rare).
7. You must submit your source code, the .java files, not the compiled .class
8. After you submit your files, redownload them and run them to make sure they are what you intended to submit. You are responsible if you submit the wrong files.

Sorting

For this assignment you will be coding 5 different sorts: insertion sort, selection sort, merge sort, quick sort, and LSD radix sort. In addition to the requirements for each sort, to test for efficiency, we will be looking at the number of comparisons made between elements while grading.

For each of the sorting algorithms, you may assume that the arrays you are sorting will not contain null. You should also assume that arrays may contains any number of duplicate elements.

Your implementations must match what was taught in lecture and recitation to receive credit. Implementing a different sort or a different implementation for a sort will receive no credit even if it passes comparison checks.

Comparator

Each method (except radix sort) will take in a comparator and use it to compare the elements of the array in various algorithms described below and in the sorting file. You must use this comparator as the number of comparisons performed with it will be used when testing your assignment.

Generic Methods

Most of the assignments for this class so far have utilized generics by incorporating them into the class declaration. However, the rest of the assignments will have you implement various algorithms as static methods in a utility class. Thus, the generics from here on will use generic methods instead of generic classes (hence the <T> in each of the method headers and javadocs).

Inplace Sorts

Some of the sorts below are inplace sorts. This means that the items in the array passed in aren’t copied over to another data structure. Note that you can still create variables that hold only one item; you cannot create another data structure such as array or list in the method.

Stable Sorts

Some of the sorts below are stable sorts. This means that duplicates should remain in the same relative positions after sorting as they were before sorting.

Insertion Sort

Insertion sort should be inplace and stable. It should have a worst case running time of O(n²) and a best case running time of O(n).

Note that, for this implementation, you should sort from the beginning of the array. This means that after the first pass, indices 0 and 1 should be relatively sorted. After the second pass, indices 0-2 should be relatively sorted. After the third pass, indices 0-3 should be relatively sorted, and so on.

Selection Sort

Selection sort should be inplace and unstable. It should have a worst case running time of O(n²) and a best case running time of O(n²). You can implement either the minimum version or the maximum version; both are acceptable since they will both yield the same number of comparisons.

Merge Sort

Merge sort should be out of place and stable. It should have a worst case running time of O(nlogn) and a best case running time of O(nlogn).

LSD Radix Sort

LSD Radix sort should be out of place and stable. It should have a worst case running time of O(kn) and a best case running time of O(kn), where k is the number of digits in the longest number. You will be implementing the least significant digit version of the sort. You will be sorting ints. Note that you CANNOT change the ints into Strings at any point in the sort for this exercise. The sort must be done in base 10. Also, as per the forbidden statements section, you cannot use anything from the Math class besides Math.abs(). However, be wary of handling overflow if you use Math.abs()!

Quick Sort

Quick sort should be inplace and unstable. It should have a worst case running time of O(n²) and a best case running time of O(nlogn). Your implementation must be randomized as specified in the method’s interface.

A note on JUnits

We have provided a very basic set of tests for your code, in SortingStudentTests.java. These tests do not guarantee the correctness of your code (by any measure), nor do they 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 Canvas under Files, 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 on Canvas, under Files, 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 Tim Aveni ([email protected]) with the subject header of “[CS 1332] 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 may lose points.

Vulgar/Obscene Language

Any submission that contains profanity, vulgar, or obscene language will receive an automatic zero on the assignment. This policy applies not only to comments/javadocs but also things like variable names.

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:

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 LinkedNode<Integer>() instead of new LinkedNode(). 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.

• package
• arraycopy()
• clone()
• assert()
• Arrays class
• Array class
• Thread class
• Collections class
• toArray()
• Reflection APIs
• Inner or nested classes
• Lambda Expressions
• Method References (using the :: operator to obtain a reference to a method)
• Anything besides abs() in the Math class (for this homework only)
• String class (for this homework only)

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

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. There are several, but we’ve noted the ones to edit.

1. java

This is the class in which you will implement the different sorting algorithms. Feel free to add private static helper methods but do not add any new public methods, new classes, instance variables, or static variables.

2. java

This is the test class that contains a set of tests covering the basic operations on the Sorting class. 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.