#!/usr/bin/perl

use strict;

my @sorted_list = qw(a b c d e f g h i j k l m n);
my @new_list;
my $cols = '3';
my $element = '0';

while ($element <= $#sorted_list) {
  for my $x (0..(@sorted_list / $cols)) {
    push @{$new_list[$x]}, $sorted_list[$element++];
  }
}

for my $row (@new_list) {
  for (@{$row}) {
    print "$_ ";
  }
  print "\n";
}

__END__
a f k 
b g l 
c h m 
d i n 
e j