Skip to content

Instantly share code, notes, and snippets.

@mattbarackman

mattbarackman/CheckerboardKarel.java

Created September 12, 2012 03:03
Show Gist options

  • Select an option

    Learn more about clone URLs
  • Save mattbarackman/3703993 to your computer and use it in GitHub Desktop.

Select an option

Learn more about clone URLs
Save mattbarackman/3703993 to your computer and use it in GitHub Desktop.
Download ZIP

Revisions

  1. mattbarackman created this gist Sep 12, 2012.
    131 changes: 131 additions & 0 deletions CheckerboardKarel.java
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,131 @@
    /*
    * File: CheckerboardKarel.java
    * ----------------------------
    * The CheckerboardKarel class should draw a checkerboard using
    * beepers, as described in Assignment 1. Karel will start in
    * the bottom left-corner facing East and will place a beeper on
    * its current location. It will start by going east, and snaking
    * up the board, placing a beeper on every other square. It should
    * be able to handle any size grid.
    *
    * Matt Barackman
    * 9.3.2012
    */

    import stanford.karel.*;

    public class CheckerboardKarel extends SuperKarel {


    /*METHOD: run()
    *
    *pre-condition:
    *see above
    *
    *post-condition:
    *completed checkerboard with Karel in either
    *of the top two corners (the right side for grids with an odd
    *number of rows, the left side for grids with an odd number
    *of lines).
    *
    *Note: While this method does eventually complete the
    *checkerboard, this bit of code really initializes Karel's
    *motion starting with the bottom line.
    */

    public void run(){
    putBeeper();
    completeEastLine();
    }

    /*
    *METHOD: completeEastLine()
    *
    *pre-condition:
    *Karel is facing East at the left-most square of a new line.
    *
    *post-condition
    *Karel is either facing West on the next line
    *up or program is finished.
    *
    *
    *Note: completeEastLine and completeWestLine make use of
    *mutual recursion to have Karel alternate rows to complete
    *the checkerboard.
    */

    private void completeEastLine(){
    alternateToWall();
    turnLeft();
    if (frontIsClear()){
    startNextLine();
    turnLeft();
    completeWestLine();
    }
    }

    /*METHOD: completeWeestLine()
    *
    *pre-condition:
    *Karel is facing West on a new line.
    *
    *post-condition:
    *Karel is either facing East on the next line up or program
    *is finished.
    */

    private void completeWestLine(){
    alternateToWall();
    turnRight();
    if (frontIsClear()){
    startNextLine();
    turnRight();
    completeEastLine();
    }
    }

    /*METHOD: startNextLine()
    *
    *pre-condition:
    *Karel is at the end of a line facing the next row up and he may or may
    *not be presently on a beeper.
    *
    *post-condition:
    *Karel has now moved to the next row up and is still facing
    *up. Karel has also placed a beeper on his current square
    *if he wasn't on one before and hasn't placed one if he was
    *on one before.
    */

    private void startNextLine(){
    if (beepersPresent()){
    move();
    }
    else {
    move();
    putBeeper();
    }
    }

    /*METHOD: alternateToWall()
    *pre-condition:
    *Karel is either facing East or West at the beginning of a
    *new line.
    *
    *post-condition:
    *Karel has now traversed the line and has in doing so has
    *placed beepers on every other square.
    */

    private void alternateToWall(){
    while (frontIsClear()){
    if (beepersPresent()){
    move();
    }
    else {
    move();
    putBeeper();
    }
    }
    }
    }