// ADAPTED FROM:https://stackoverflow.com/questions/53722004/generic-quicksort-implemented-with-vector-and-iterators-c

static void serialQuicksort(QSVector::iterator b, QSVector::iterator e) {

    if ((e - b) < 2)
        return;


  // do shuffle
  QSVector::iterator i = b, j = e-1;
  auto pivot_value = (i + (j-i)/2)->value;
  if(i->value < pivot_value)
        while ((++i)->value < pivot_value) ;
  if(j->value > pivot_value)
        while ((--j)->value > pivot_value) ;

  while (i < j)
    {
        std::iter_swap(i, j);
        while ((++i)->value < pivot_value) ;
        while ((--j)->value > pivot_value) ;
    }
    j++;

  // recursive call
  serialQuicksort(b, j);
  serialQuicksort(j, e);
}