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.*;

/*
 * PRE-CONDITIONS:  Karel starts in lower-left corner facing east
 *                  Square world
 * POST-CONDITIONS: Karel stands on a beeper in the center (or left/right
 *                  center) of First Street
 *
 */

public class MidpointFindingKarel extends SuperKarel {
    public void run () {
        spiralAreaWithBeepers();
        orientAndHeadSouth();
        // double the beeper count on center, to find later
        putBeeper();
        // go to starting position
        goHome();
        unSpiralBeepers();
        goHome();
        goToBeeper();
    }
    private void spiralAreaWithBeepers() {
        while (noBeepersPresent()) {
                dropBeepersEast();
                dropBeepersNorth();
                dropBeepersWest();
                dropBeepersSouth();
        }
    }
    private void orientAndHeadSouth() {
        while (notFacingSouth()) {
            turnLeft();
        }
        while (frontIsClear()) {
            move();
        }
    }
    private void goHome() {
        while (notFacingWest()) {
            turnLeft();
        }
        while (frontIsClear()) {
            move();
        }
        if (leftIsBlocked()) {
            turnAround();
        } else {
            orientAndHeadSouth();
            turnLeft();
        }
    }
    private void unSpiralBeepers() {
        while (beepersPresent()) {
            pickBeepersEast();
            pickBeepersNorth();
            pickBeepersWest();
            pickBeepersSouth();
        }
    }
    private void goToBeeper() {
        while (noBeepersPresent()) {
            move();
        }
    }
    private void dropBeepersEast() {
        while (facingEast()) {
            if (noBeepersPresent()) {
                putBeeper();
            }
            if (frontIsClear()) {
                move();
                if (beepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
                move();
            }
        }
    }
    private void dropBeepersNorth() {
        while (facingNorth()) {
            if (noBeepersPresent()) {
                putBeeper();
            }
            if (frontIsClear()) {
                move();
                if (beepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
                move();
            }
        }
    }
    private void dropBeepersWest() {
        while (facingWest()) {
            if (noBeepersPresent()) {
                putBeeper();
            }
            if (frontIsClear()) {
                move();
                if (beepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
    private void dropBeepersSouth() {
        while (facingSouth()) {
            if (noBeepersPresent()) {
                putBeeper();
            }
            if (frontIsClear()) {
                move();
                if (beepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
    private void pickBeepersEast() {
        while (facingEast()) {
            if (beepersPresent())   {
                pickBeeper();
            }
            if (frontIsClear()) {
                move();
                if (noBeepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
    private void pickBeepersNorth() {
        while (facingNorth()) {
            if (beepersPresent())   {
                pickBeeper();
            }
            if (frontIsClear()) {
                move();
                if (noBeepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
    private void pickBeepersWest() {
        while (facingWest()) {
            if (beepersPresent())   {
                pickBeeper();
            }
            if (frontIsClear()) {
                move();
                if (noBeepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
    private void pickBeepersSouth() {
        while (facingSouth()) {
            if (beepersPresent())   {
                pickBeeper();
            }
            if (frontIsClear()) {
                move();
                if (noBeepersPresent()) {
                    turnAround();
                    move();
                    turnRight();
                    move();
                }
            } else {
                turnLeft();
            }
        }
    }
}