CSE 2320 - Assignments - Assignment 9

Submit to Blackboard before the deadline. You will be able to revise your answers until the deadline with no penalty.

IMPORTANT: By submitting your answers, you are certifying that these answers have been exclusively your own work. All students enrolled in this course are expected to adhere to the UT Arlington Honor Code:

I pledge, on my honor, to uphold UT Arlington's tradition of academic integrity, a tradition that values hard work and honest effort in the pursuit of academic excellence. I promise that I will submit only work that I personally create or contribute to group collaborations, and I will appropriately reference any work from other sources. I will follow the highest standards of integrity and uphold the spirit of the Honor Code.

(Programming) Task 1 (40 pts.)

Implement a variation of radix sort (either MSD or LSD is fine) with the following specifications:

The function signature should be: void radixsort(int * items, int length, int radix)
Radix can be any number between 2 and 100,000.

Note radix_sort.c contains a function radixMSD2(int * items, int length, int radix), which implements MSD radix sort but only works with a radix that is 2, 4, 16, 256, 65536, as well as an implementation of LSD radix sort for radix = 2. Feel free to reuse as much of that code as you find useful. Similarly, feel free to reuse as much of the textbook code as you find useful.

Submit your function in a program called task1.c.

(Programming) Task 2 (20 pts.)

Compare, for various radix values, the running time of your solution for task 1 with the performance of the version of quicksort defined by textbook programs 7.1 and 7.2, by running both versions on omega, on an array of integers, that contains 100 million integers in random order.

The values of the integers should be uniformly distributed between 0 and 2 billion. For your implementation of MSD radix sort, you should test it using the following radix values:

2
10
1000
100000

For this task, you should submit two things:

A C file, called task2.c, that you used to do the testing. You should use a single C file for the testing, where a commandline argument specifies which of the test cases is run:
- Commandline argument 0 means running the test case with quicksort and 100 million integers in random order.
- Any other commandline argument N means running the test case with your implementation of MSD radix sort, using N as the radix, and 100 million integers in random order.
In your answers document, report the running time that you observed for each of the five cases.

Task 3 (10 pts.)

Given the capabilities of modern computers, discuss whether it would it make sense to use MSD radix sort if we have to sort 100 million 64-bit positive integers, and each integer has a value between zero and 2⁶⁴-1. Discuss what choice you would make for the radix and why, so as to optimize performance.

Task 4 (15 pts.)

Suppose that we need to sort 100 million integers, whose values range from -1,000,000 to +1,000,000. Describe, in pseudocode, an algorithm based on the MSD radix sort algorithm that would be able to sort these numbers in linear time.

Task 5 (15 pts.)

Suppose that we need to sort 100 million real numbers (represented as numbers of type float in C), whose values are between -1 and 1. Describe, in pseudocode, an algorithm based on the MSD radix sort algorithm that would be able to sort these numbers in linear time, assuming that the values of the numbers are spread out relatively evenly within the [-1, 1] range. Explain why this assumption (that the numbers are spread out relatively evenly) is important for the performance of your algorithm.

How to submit

The assignment should be submitted via Blackboard. Submit a ZIPPED directory called Firstname_Lastname.zip. No other forms of compression are accepted, contact the instructor or TA if you do not know how to produce .zip files. The zipped directory should contain the following documents:

task1.c
task2.c
answers.xxx

As stated on the course syllabus, programs must be in C or Java, and must run on omega.uta.edu. If you want to do this in any language other than C, you have to re-implement in that language all the code that is currently provided and implemented in C. If you want to use another language or platform, you must obtain prior written approval via e-mail by the instructor.

IMPORTANT: Pay close attention to all specifications on this page, including file names and submission format. Even in cases where your answers are correct, points will be taken off liberally for non-compliance with the instructions given on this page (such as wrong file names, wrong compression format for the submitted code, and so on). The reason is that non-compliance with the instructions makes the grading process significantly (and unnecessarily) more time consuming. Contact the instructor or TA if you have any questions.

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