# Homework 8: Sorting solution

Sorting

For this assignment you will be coding 6 different sorts: cocktail sort, insertion sort, selection sort, quick

sort, merge sort, and LSD radix sort. In addition to the requirements for each sort, we will be looking

at the number of comparisons made between elements while grading.

Comparator

Each sorting method (except radix sort) will take in a comparator and use it to sort the elements of the

array using various sorting algorithms described below and in the sorting file.

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 array or list. Note that you can still create variables that hold only one item; you cannot

create another 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.

Cocktail Sort

Cocktail sort should be inplace and stable. It should have a worst case running time of O(n

2

) and a best

case running time of O(n).

1

Homework 8: Sorting Due: See T-Square

Insertion Sort

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

2

) 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, index 0 and 1 should be considered as sorted. After the second pass, index 0-2 should

be considered as sorted. After the third pass, index 0-3 should be considered as sorted, and so on.

Selection Sort

Selection sort should be inplace. It should have a worst case running time of O(n

2

) and a best case

running time of O(n

2

).

Quick Sort

Quick sort should be inplace. It should have a worst case running time of O(n

2

) and a best case running

time of O(n log n).

Your implementation of quick sort must match the method shown in lecture; otherwise, you may

not receive full credit for the sort.

Merge Sort

Merge sort should be stable. It should have a worst case running time of O(n log n) and a best case

running time of O(n log n).

Radix Sort

Radix sort should be 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 sorting ints. Note

that you CANNOT change the ints into Strings at any point in the sort for this exercise. In addition,

the sort must be done in base 10.

If you need to calculate the result of a number raised to a power, you should use the pow() method

we have provided. You may only use Math.abs() from the Math class.

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 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

2

Homework 8: Sorting Due: See T-Square

please email Carey MacDonald ([email protected]) 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.

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<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()

• Reflection APIs

• Inner, nested, or anonymous classes

• Anything besides Math.abs() in the Math class (for this homework only)

Debug print statements are fine, but nothing should be printed when we run them. We expect clean

runs - printing to the console when we’re grading will result in a penalty. If you use these, we will take

off points.

3

Homework 8: Sorting Due: See T-Square

Provided

The following file(s) have been provided to you. There are several, but you will edit only one of them.

1. Sorting.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. SortingStudentTests.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.

Deliverables

You must submit all of the following file(s). Please make sure the filename matches the filename(s)

below, and that only the following file(s) are present. T-Square does not delete files from old uploads;

you must do this manually. Failure to do so may result in a penalty.

After submitting, 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. Sorting.java

For this assignment you will be coding 6 different sorts: cocktail sort, insertion sort, selection sort, quick

sort, merge sort, and LSD radix sort. In addition to the requirements for each sort, we will be looking

at the number of comparisons made between elements while grading.

Comparator

Each sorting method (except radix sort) will take in a comparator and use it to sort the elements of the

array using various sorting algorithms described below and in the sorting file.

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 array or list. Note that you can still create variables that hold only one item; you cannot

create another 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.

Cocktail Sort

Cocktail sort should be inplace and stable. It should have a worst case running time of O(n

2

) and a best

case running time of O(n).

1

Homework 8: Sorting Due: See T-Square

Insertion Sort

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

2

) 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, index 0 and 1 should be considered as sorted. After the second pass, index 0-2 should

be considered as sorted. After the third pass, index 0-3 should be considered as sorted, and so on.

Selection Sort

Selection sort should be inplace. It should have a worst case running time of O(n

2

) and a best case

running time of O(n

2

).

Quick Sort

Quick sort should be inplace. It should have a worst case running time of O(n

2

) and a best case running

time of O(n log n).

Your implementation of quick sort must match the method shown in lecture; otherwise, you may

not receive full credit for the sort.

Merge Sort

Merge sort should be stable. It should have a worst case running time of O(n log n) and a best case

running time of O(n log n).

Radix Sort

Radix sort should be 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 sorting ints. Note

that you CANNOT change the ints into Strings at any point in the sort for this exercise. In addition,

the sort must be done in base 10.

If you need to calculate the result of a number raised to a power, you should use the pow() method

we have provided. You may only use Math.abs() from the Math class.

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 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

2

Homework 8: Sorting Due: See T-Square

please email Carey MacDonald ([email protected]) 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.

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<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()

• Reflection APIs

• Inner, nested, or anonymous classes

• Anything besides Math.abs() in the Math class (for this homework only)

Debug print statements are fine, but nothing should be printed when we run them. We expect clean

runs - printing to the console when we’re grading will result in a penalty. If you use these, we will take

off points.

3

Homework 8: Sorting Due: See T-Square

Provided

The following file(s) have been provided to you. There are several, but you will edit only one of them.

1. Sorting.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. SortingStudentTests.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.

Deliverables

You must submit all of the following file(s). Please make sure the filename matches the filename(s)

below, and that only the following file(s) are present. T-Square does not delete files from old uploads;

you must do this manually. Failure to do so may result in a penalty.

After submitting, 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. Sorting.java

Starting from: $30

You'll get 1 file (127.7KB)