sub comb_sort {
  my @v = @_;
  my $max = scalar (@v);
  my $gap = $max;
  while (1) {
     my $swapped = 0;
     $gap = int ($gap / 1.3);
     $gap = 11 if $gap == 10 or $gap == 9; # (Combsort11 optimization)
     $gap = 1 if $gap < 1;
     my $lmax = $max - $gap - 1;
     foreach my $i (0..$lmax) {
          ($v[$i], $v[$i+$gap], $swapped) = ($v[$i+$gap], $v[$i], 1) if $v[$i] > $v[$i+$gap];
     }
     last if $gap == 1 and $swapped == 0;
  }
  return @v;
}