Algorithm Description

1. Algorithm Description

2. Dinky Database Dantai • The Dinky Database Dantai has received an unreasonable number of complaints about the speed of their Zip Code sorting procedure • DDD has hired you as a contractor. • In particular, they want you to analyze their system and determine what is slowing down the procedure. • Once you have determined the problem, they would like you to recommend a solution to fix the problem.

3. Bubble Sort • Upon examining the sorting algorithm, you have determined that DDD is using Bubble Sort to sort its data. • As a knowledgeable individual on the subject of sorting algorithms, you are aware of a number of more efficient alternatives.

4. Zip Code sorting • Note: DDD’s records include: • 5 digit US Zip Codes • 95064 • 9 digit numeric US Zip Codes • 95064-0028 • 6 digit alpha-numeric Canadian Zip codes • V8V 1X1

5. Choosing your Algorithm • Solid choices: Merge sort or Quicksort • For students with a limited programming background, Quicksort is slightly easier to understand and explain. • Other choices: • Radix sort • Bucket sort • Heap sort

6. Writing for Multiple Audiences • You have two basic writing tasks: • An Executive Summary for the Manager in charge of deciding whether to authorize the change. • An Implementation section for the programmers who will be writing the new algorithm.

7. Executive Summary • This manager may or may not have any technical expertise. • His or her last experience with mathematics beyond Algebra may have been in High School. • Any explanations like “Quicksort’s best-case performance works in O(n log n), as opposed to Bubble Sort’s O(n2)”may as well be written in Esperanto. • Focus more on why your replacement algorithm is efficient than why Bubble Sort is inefficient.

8. Executive Summary (cont.) • Present your arguments in terms the Executive is interested in. • Faster. • Less expensive. • Easy to implement. • The Executive Summary should be brief. • Typically 1-2 pages.

9. Implementation • You are writing to Novice programmers. • You don’t know what system they’re writing for, or what programming language they’re using. • Your job is to explain how the algorithm works, not to program it for them.

10. Implementation (cont.) • Define your terms: • Recursion • If you are recommending a recursive algorithm, you will need to define recursion. (Most sorting algorithms use recursion) • Divide and Conquer • Again, not all sorting algorithms use this technique, but for those that do, explain the term.

11. Illustrations and Figures • A simple graph can describe rather eloquently how efficient your algorithm can be. • Make certain your graph will be clear to its intended audience. • Examples of your sorting algorithm can help the reader understand. • Give a short list of numbers and demonstrate how your sorting algorithm would sort them, step by step. • You are free to make your own examples, or borrow (properly cited) examples from the internet or elsewhere.

12. Pseudo-code • It is acceptable to use short bits of Pseudo-code to demonstrate your methods. • Do not use long sections of Pseudo-code. • Your job is to explain how the process works, not to write the program for them. • In short, you can use Pseudo-code to illustrate something you’ve explained in English. • But you may not simply write out the Pseudo-code for the process and then explain it line by line.