Hi blokhead, I've managed, to stored it into an array by doing this:

   my @cliques = ();
   
    $regex .= '(?{ push (@cliques, join(" ", map $$_, 1..$k)) })(?!)';
    $string =~ /$regex/x; 
   
   print join("\n", @cliques), "\n";
[download]

I just need to understand a bit on (?{}) part.
Glad I learnt that.

Thanks a again. for your kind suggestion. I will play around with your combinatorial subroutine. It seems easier to understand than Regex approach.

BTW, thanks for the wonderful links you have on various CS items in your "monks home", I found it very useful.

Gratefuly yours, Edward WIJAYA