#!/usr/bin/perl -w 
use strict; 
use Data::Dumper; 

my @b = p( 1, 2, 3 ); 
print Dumper( @b ); 

sub p { 
  my@a=[];for(0..@_){@a=map{my@b=@$_;my@c=@_;for(@b){my$e=$_;for(1..@c){my$d=shift@c;last if$d eq$e;push @c,$d}}@c?map{[@b,$_]}@c:[@b]}@a}@a
}