@Override
    protected Map<String, Integer> compute() {
        if (data.length > L) {
            return ForkJoinTask.invokeAll(createSubtasks())

        } else {
            return processing(arr);
        }
    }

    private Collection<PoolWorker> createSubtasks() {
        List<PoolWorker> newTasks= new ArrayList<>();
        newTasks.add(new PoolWorker(
          Arrays.copyOfRange(data, 0, data.length / 2)));
        newTasks.add(new PoolWorker(
          Arrays.copyOfRange(data, data.length / 2, data.length)));
        return newTasks;
    }

    private Map<String, Integer> processing(String data) {
        //Putting in a map
    }
}