Graphic by Keith Ohlfs

CS111, Wellesley College, Fall 1999 Problem Set 4 Due: Friday, October 15 by 4:00 p.m.

Problem Set 4

Problem 1 Notes, Hints, Suggestions

• To save yourself time, think carefully about your strategy before writing any code! Draw lots of pictures and convince yourself that it works. You are encouraged to develop the strategy with your classmates, but you should code it on your own.
  
  
• You are encouraged to define any auxiliary Follower methods that you find helpful. In particular, you may find it helpful to define methods that return a boolean value indicating the position of the next bagel relative to the buggle's current position and heading. For example, here is a method indicating if the next bagel is in front of the buggle:

  public boolean isBagelInFront () {
    if (isFacingWall()) {
      return false;
    } else {
      brushUp(); // don't change the state of the environment during inquiry
      forward(); 
      boolean result = isOverBagel();
      backward();
      brushDown(); // return to original state before inquiry
      return result;
    }
  }
  

  You might also want methods that check for a bagel to the left or right of a buggle.

• You should not need to write very much code to implement your strategy. My solution for the tick method takes less than 20 lines, much of which is whitespace, comments, and method headers.
  
  
• Strive to make your code as readable and understandable as possible. Use meaningful method and variable names. Use comments where appropriate. (Do not comment every line. Only use comments to explain aspects of the code that are not immediately obvious.)
  
  
• Use the Pause and Step buttons to debug your strategy. Pause pauses the execution of a running buggle. Step performs the next buggle primitive and prints the name of the primitive in the Standard Output window.
  
  
• The default grid size is 9x9. You may find it helpful to debug your strategy in a smaller grid. You can set the grid size by using the setDimensions method within the setup() method of the FollowWorld class, as shown below. Note: this problem requires that both columns and rows be odd numbers.

  public void setup() {
    setDimensions(columns,rows);
  }
  

• The paths are "randomly" generated by a so-called psuedo-random number generator. The generator is initialized with a "seed" value that guarantees that you will get the exact same "random" sequence of paths every time you reload the applet. This aids debuggability.