MidpointFindingKarel

/*
 * 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.*;

public class MidpointFindingKarel extends SuperKarel {

    public void run() {
        fillRow();
        moveBack();
        pickBeeper();
        turnAround();
        pickUpAllBeepersAtEnds();
    }
/*
 * fillRow:
 * karel will place a beeper along the 1st row, except for the last block.
 *
 * pre-conditions: karel is in the first block of the first row and facing east
 *
 * post-conditions: karel will be in the last block of the first row facing east
 */
    private void fillRow(){
        while (frontIsClear()) {
            putBeeper();
            move();
        }
    }
/*
 * moveBack:
 * karel will move back to her intital staring position.
 *
 * post-conditions: karel will be facing west
 */
    private void moveBack() {
        turnAround();
        while (frontIsClear()){
            move();
        }
    }
/*
 * pickUpAllBeepersAtEnds:
 * karel will move to all the outer beepers and remove them till only the
 * center beeper remains.
 *
 * pre-condition: must be in 1st block of 1st row and facing east.
 *
 * post-condition: karel will end up at the end of the row, either on the east
 * or west side, depending on how many blocks are in a row.
 */
    private void pickUpAllBeepersAtEnds() {
        while (frontIsClear()){
            moveToOuterBeepers();
            checkIfOuterBeeper();
        }
    }
/*
 * moveToOuterBeepers:
 * karel will conduct a test to determine which way to move to reach
 *the outer beeper farthest from her
 *
 * pre-conditions: karel must be facing east and standing on a block with no beeper.
 *
 * post-condition: karel will be on the outer beeper furthest from her starting point
 * and be facing east.
 */
    private void moveToOuterBeepers(){
        move();
        if (beepersPresent()){
            turnAround();
            move();
            turnAround();
            moveRightToOuterBeeper();
        } else {
            turnAround();
            move();
            turnAround();
            moveLeftToOuterBeeper();
        }
    }
/*
 * moveRightToOuterBeeper:
 * karel will move right to reach the outer beeper
 *
 * pre-conditions: karel must be facing east and standing on a block with no beeper.
 *
 * post-condition: karel will be on the outer beeper furthest from her starting point
 * and be facing east.
 */
    private void moveRightToOuterBeeper(){
        move();
        while (beepersPresent()){
            move();
        }
        turnAround();
        move();
        turnAround();
    }
    /*
     * moveLeftToOuterBeeper:
     * karel will move left to reach the outer beeper
     *
     * pre-conditions: karel must be facing east and standing on a block with no beeper.
     *
     * post-condition: karel will be on the outer beeper furthest from her starting point
     * and be facing east.
     */
        private void moveLeftToOuterBeeper(){
            turnAround();
            move();
            while (beepersPresent()){
                move();
            }
            turnAround();
            move();
        }
    /*
     * checkIfOuterBeeper:
     * karel will check to see if the beeper she is standing on is an outer beeper.
     * if so then karel will remove it.
     *
     * pre-conditions: karel must be standing on a beeper and facing east.
     *
     * post-conditions1: karel will be standing in the same position she was in and be facing east.
     * the only difference is that there will be no beeper.
     *
     * post-condition2: karel will be at either end of the row with her front blocked, if the beeper
     * she was on turns out to be the center beeper.
     */
        private void checkIfOuterBeeper(){
            if (frontIsClear()){
                turnAround();
                move();
                if (beepersPresent()){
                    turnAround();
                    move();
                    pickBeeper();
                } else {
                    if (frontIsBlocked()){
                        turnAround();
                        move();
                        pickBeeper();
                    } else {
                        checkOtherSide();
                    }

                }
            }
        }
    /*
     * checkOtherSide:
     * another test to double check if beeper is center or outer
     */
        private void checkOtherSide(){
            turnAround();
            move();
            move();
            if (beepersPresent()){
                turnAround();
                move();
                pickBeeper();
            } else {
                while (frontIsClear()){
                    move();
                }
            }
        }
}