public Set<Location> getEmptyLocations(int row, int col, int dist) {
        Set<Location> locations = new HashSet<>();
        for (int x = row - dist; x <= row + dist; x++) {
            if (isInBounds(x)) {
                for (int y = col - dist; y <= col + dist; y++) {
                    if (isInBounds(y) && thisTick[x][y] == null
                        && !(x == row && y == col)) {

                        locations.add(new Location(x, y));
                    }
                }
            }
        }
        return locations;
    }