kenswain.com

Another problem that I thought would kinda be simple, and in reality it was if I could have used more of Java, but turned out to be really hard. I am going to post two results here. One using some other attributes of Java and the other is going to be what it took to satisfy the class.

Simple/fast way:

/*
 * File: MidpointFindingKarel.java
 * -------------------------------
 * When you finish writing it, the MidpointFindingKarel class should
 * leave a beeper on the corner closest to the center of 1st Street
 * (or either of the two central corners if 1st Street has an even
 * number of corners).  Karel can put down additional beepers as it
 * looks for the midpoint, but must pick them up again before it
 * stops.  The world may be of any size, but you are allowed to
 * assume that it is at least as tall as it is wide.
 */


import stanford.karel.*;

/*
 * Name: 
 * Section Leader: 
 */

public class MidpointFindingKarel extends SuperKarel {

private int countI;
public void run() {
    /*
     * Find the middle of any size map.
     */
    countI =0;
    findMiddle();
    moveMiddle();
    putBeeper();
}

private void findMiddle() {
    while (frontIsClear()) {
        move();
        countI++;
    }
}

private void moveMiddle() {
    turnAround();
    for (int i=0; i < (countI /2); i++)
        move();
}


}

To satisfy class

/*
 * File: MidpointFindingKarel.java
 * -------------------------------
 * When you finish writing it, the MidpointFindingKarel class should
 * leave a beeper on the corner closest to the center of 1st Street
 * (or either of the two central corners if 1st Street has an even
 * number of corners).  Karel can put down additional beepers as it
 * looks for the midpoint, but must pick them up again before it
 * stops.  The world may be of any size, but you are allowed to
 * assume that it is at least as tall as it is wide.
 */


import stanford.karel.*;

/*
 * Name: Ken Swain
 * Section Leader: 
 */

public class MidpointFindingKarel extends SuperKarel {

public void run() {
    /*
     * Find the middle of any size map.
     * 
     * Pre-Condition: On corner of 1:1 facing east.
     * 
     * Post-Condition: Have one beeper sitting in the middle of the 1st row.
     * 
     */
    layBeepers();
    findMiddle();
    putBeeper();
    faceEast();
}

private void faceEast() {
    /*
     * Turn and face east
     */
    while (notFacingEast()) {
        turnRight();
    }
}

private void layBeepers() {
    /*
     * Pre-Condition: Karel is at 1:1 facing east.
     * 
     * Post-Condition: Karel is at the end of the row facing west.
     */
    while (noBeepersPresent()) {
        putBeeper();
        if (frontIsClear()) {
            move();
        }
    }
    turnAround();
}

private void findMiddle() {
    /*
     * Pre-condition: Karel starts on row 1 facing west
     * 
     * Post-condition: Karel is standing in the center of row 1
     * 
     */
    for (int i=0; i < 2; i++) {
        moveUntilHitWallOrNoBeepers();
    }
    move();
    while (beepersPresent()) {
        cleanEnds();    
    }
    turnAround();
    move();
}

private void cleanEnds() {
    /*
     * Pre-condition: beepers are still on the map and we are starting on one.
     * 
     * Post-condition: we are standing in the center of the map with no beepers.
     */
    while (beepersPresent()) {
        move();
    }
    turnAround();
    move();
    pickBeeper();
    move();
}

private void moveUntilHitWallOrNoBeepers() {
    /*
     * Move to the end of the line.
     */
    while (frontIsClear()) {
        move();
    }
    turnAround();
    pickBeeper();
}


}