for my $nnot (
    map { $solution[-1] + $_, $solution[-1] - $_ }
    grep { $availableIntervals[$_] > 0 }
    (1 .. 11)
  ) {

##</code><code>##

  for my $nnot (
    map { 
      $availableIntervals[$_] > 0 
        ? ( $solution[-1] + $_, $solution[-1] - $_ )
        : ()
    } (1 .. 11)
  ) {