a.
private boolean hallIsClear() {
    if (pos == hall.length - 1 && facingRight) {
        return true;
    }
    else if (pos == 0 && !facingRight) {
        return true;
    }
    else {
        return false;
    }

b.
private void move() {
    if (hall[pos] > 0) {
        hall[pos] -= 1;
    }
    if (hall[pos] == 0) {
        if (!forwarMoveBlocked()) {
            if (facingRight) {
                pos += 1;
            }
            else {
                pos -= 1;
            }
        else {
            if (!facingRight) {
facingRight == true;
            else {
                !facingRight;

c.
public int clearHall() {
    int numMoves = 0;
    while (!hallIsClear()) {
        move();
        numMoves++;
    }
    return numMoves;
}