CS 3100
Fall 2008
Lab 2
Due Wednesday, October 15
Comparing Sorting Algorithms
Based on an assignment created by Dr.  Sarraille.

Write a program that REPEATEDLY:
1. prompts the user to enter a filename,
2. opens the file,
3. reads a comment from the first line,
4. reads an integer N from the second line (e.g. N = 1000),
5. reads N integers from the rest of the file, putting them into consecutive locations in an array,
6. writes the name of the input file,
7. writes the comment from the input file,
8. sorts an identical copy of the array using each of the following methods:
• selection sort
• insertion sort
• quick sort
• merge sort
9. writes a report of the number of compares and moves done in each sort, and
10. asks the user if they wish to continue.
The program will continue UNTIL the user wishes NOT to continue.

DETAILS:

Your program must make a little announcement (examples to follow) just before starting and just after completing each run of one of the four sorting functions. This will allow you to get a sense of how long each individual algorithm takes to do its work.

Your program must pass in a new copy of the original array each time it calls a sorting function. We don't want the first function call to be the only one that really sorts the original array!

When you count "moves" count the number of times that an element of the list is copied from one location to another (with an assignment statement). Each call to the function swap counts as three moves.

When counting compares, count only comparisons of list elements (the things that are being sorted), not the array indices. For example, if the array you are using is named "data" the line of code:

if (data[j] < data[j - 1])

contains a comparison that you would have to count, because it is a comparison of two elements in the list. On the other hand, the line of code:

while (i < j)

does not compare elements of the list. It is a comparison of array indices only. Therefore you must not count that comparison.

The line of code

for (;(loc > 0) && (data[loc-1] > nextItem)

contains one comparison that you should not count and one comparison that you should count.

You should not count "loc > 0" because it compares indices. You should count "data[loc-1] > nextItem" because it compares a list element with (a copy of) another list element.

Keep in mind that it may be a little "tricky" to insert the code that counts the comparisons executed in if-clauses and loop conditions. Give the problem due thought and consideration.

The code you need to perform the sorting is contained in a set of files:
You will need to modify this code so that it takes care of the counting of the compares and the moves. That will mean adding parameters to functions and adding pieces of code that do counting within functions. We can discuss more details of this in class. I also included a little prototype of a driver program called driver.cpp You can get ideas from driver.cpp for formulating the program you do for this assignment.

To do some preliminary testing, you can compile the whole "package" of driver plus sorting code on the SUN Ultra's with this command:

g++ *.cpp

This assumes that the only source files in your current working directory are the ones that are part of the "package." Of course, to complete the assignment you will need to write another driver that is fully functional.

SAMPLE INPUT AND OUTPUT:

Let's look at two sample input files and the corresponding output in order to better understand what the format of the files and outputs has to be. The sample input files are ord50 and ran1000 The corresponding sample program output: sample.out Note: When you see a message such as "selection sort starting ... done" understand that the program first writes "selection sort starting ... " then performs the selection sort, and then writes "done."

TESTING:

Lists can be small, medium, and large in size. They can also be random, ordered, or reverse-ordered. You need to test all the possible combinations (there are 9). Dr. Sarraille has a package containing all the inputs you need here (but don't click until you are ready to download):

ftp://www.cs.csustan.edu/pub/john/dataFiles.tar.gz

(Some browsers may not access the link above properly. If one browser has a problem, try another. Clicking on the link should download and unpack the files on most systems. You may have to do an extra step to unpack the file.)

In the header of your program, include a paragraph or two describing what you learned from writing and testing this program. Do your very best to make this well-written. This will be another aspect of the assignment that will count heavily.

WHAT TO TURN IN:

Here is the list of things you have to turn in:
1. At the start of class on the due date, place the following items on the "counter" in front of me:

• a hardcopy of your final version of the program source code, and

Make sure that all of the code and script content shows on the paper. Make sure all content is plainly readable and properly formatted.

2. Upload to the homework submission system before midnight on the due date:

One shell archive file (only one) containing all things listed below.
1. Your final versions of these files that I gave you:
• selectionSort.cpp
• selectionSort.h
• insertionSort.cpp
• insertionSort.h
• quicksort.cpp
• quicksort.h
• mergesort.cpp
• mergesort.h
• swap.cpp
• swap.h