#!/usr/bin/perl  
use warnings;
use strict;  
use Algorithm::Permute;

my @a=qw/ A B C /; 
# You can create r of n objects permutation generator, where r <= n
  my $p=new Algorithm::Permute(@a,2);

  while (@res = $p->next) {
    print join(", ", @res), "\n";
  }  
exit;
# Script ends here