public static Tour combine(Tour a, Tour b) {
        int start = r.nextInt(a.getStopCount());
        int end = r.nextInt(a.getStopCount());

        if (start > end) {
            int temp = start;
            start = end;
            end = temp;
        }

        int slice_length = end - start + 1;

        Integer[] temp_a = Arrays.copyOfRange(a.getStops(), start, end);
        ArrayList<Integer> child_ids = new ArrayList<>();

        for (int id : temp_a) {
            child_ids.add(id);
        }

        if(slice_length != a.getStopCount()) {
            for (int id : b.getStops()) {
                if (!child_ids.contains(id)) {
                    child_ids.add(id);
                }
            }
        }

        Tour tour = new Tour(child_ids.toArray(new Integer[child_ids.size()]));

        return tour;
    }