CompSci 201: Data Structures & Algorithms

You can browse the code we provide and you can snarf it using our Ambient/Eclipse plugin --- check out the instructions on how to download the ambient system and how to use it to check out a project.

The snarf url for this CompiSci 201 is http://www.cs.duke.edu/courses/compsci201/spring13/snarf/.

Provided Code/Classes

You are provided with four classes.

1. The class HangmanStats will be the class that you'll use/modify in part 1 -- the statistical/analytical part of the program. It has a main method:
   public static void main(String args[])
   that executes the code in the class HangmanStats.

2. The class HangmanFileLoader loads a textfile and has a method to select and return a random word. Look in the sample code in HangmanStats and HangmanGame to see how to use the class. You shouldn't need to modify this code at all.

3. The class HangmanExecuter has the public static void main(String args[]) function that is the starting point of the Hangman game you will write. It creates a HangmanGame and invokes the play method. You can write the game without modifying HangmanExecuter. If you do modify it, please include an explanation in your README.

4. The class HangmanGame is the game-playing code, you'll modify the play method and you may add new methods or state/instance variables to this class.

Statistical/Forensic Analysis

You are given code in HangmanStats that gives you the number of words with 4 letters when HangmanLoader.getRandomWord is called 10,000 times. When we modified this code to call HangmanLoader.getRandomWord 10,000 times for word-lengths of 4-10 we obtained the below results from one run.

word length	# words
4	2209
5	3792
6	4959
7	5412
8	5379
9	4947
10	4059

If run again, the numbers above will be similar, but different. You'll need to decide on a strategy and write code to get estimates of the number of different words for each word-length from 4-20 (inclusive).

Java Help

Expect to spend some time getting used to the Java language. We have written a handy-dandy cheat sheet that shows example java code and matches it to Python and Matlab. Also, the Java API docs provide info on what sort of operations Strings or other objects support. Using google can also work.

Coding Guidelines

Well written code is easy to read and makes graders happy.

The sample output on the assignment writeup page should be generically followed in that the user should see a representation of the secret word with guesses filled in, the letters used so far, and so on.

• Methods should be brief/short, ideally 10-20 lines, but that's a guideline, not a requirement.

• Methods that do more than one thing are candidates to be divided into more than one method so that each method does only one thing. A prime candidate is the play method, it will consist of picking letters, updating word-displays, determining if the game should continue, validating input, and so on. In principle, each of these should be a different method, though in practice that's not always possible.

• A method should minimize its side-effects. Changing one parameter and returning a value are ok. Changing multiple parameters and returning a value should be avoided, though sometimes this is ok too -- have a justification for the code you write.

• Use good method and parameter names and follow the Java naming guidelines.