@array = (2 ,4, 3, 8, 9, 12, 13, 20, 18, 7 )
@sortedarray = (20, 18, 13, 12, 9, 8, 7, 4, 3, 2)
After replacement (A, A, -, -, -, -, -, -, -, -, B, B)
@finalarray = (B, -, B, -, -, -, -, A, A , -)

##</code><code>##

#! perl -slw
use strict;

my @array = (2 ,4, 3, 8, 9, 12, 13, 20, 18, 7 );
my @orderedIndeces = sort{
    $array[ $b ] <=> $array[ $a ]
} 0 .. $#array;

my $n = scalar @array;
my $twentyperc = $n * 0.2;





for my $i (0..$#orderedIndeces){
    if ( $i < $twentyperc) {

     $array[$orderedIndeces[$i]] = "A";

    print "$array[$orderedIndeces[$i]]\t";
    }
    elsif ($i >= $n-$twentyperc){
         $array[$orderedIndeces[$i]] = "B";
          print "$array[$orderedIndeces[$i]]\t";

     }
     else{
          $array[$orderedIndeces[$i]] = "-";
          print "$array[$orderedIndeces[$i]]\t";
     }
   print "\n";

}