#!/usr/bin/perl -w
use strict;

my @zeichen = ("A".."C");
my $laenge = 3;
my $start = 0;
my $pos = $laenge;

my %string = {"1" => 'A', "2" => 'A', "3" => 'A'};

my $i=0;

while ($pos >= 1) {

  for my $aktuell (@zeichen) { 
    $string{$laenge} = $aktuell;
    print $string{$_} for (1..$laenge);
    print "\n";
  }
  if ( $string{$pos} eq $zeichen[scalar(@zeichen)-1] ) {
    $pos--;
    $i=0;
    $string{$laenge} = $zeichen[0];
  }
  $string{$pos} = $zeichen[$i];
  $i++;
}

#!/usr/bin/perl

use strict;
use warnings;
use Math::Combinatorics;

my @zeichen = ('A'..'C');
my $count   = 3;

my $combo   = Math::Combinatorics->new( count => $count, 
                                        data  => [(@zeichen) x $count]);

while(my @combo = $combo->next_combination){
    print join(' ', @combo)."\n";
}

#!/usr/bin/env ruby -w

substitute = { '0' => 'A', '1' => 'B', '2' => 'C' }

(0 .. 26).each do | i |
  puts i.to_s(3).rjust(3, '0').gsub(/./) { | k | substitute[k] }
end

#!/usr/bin/perl

use strict;
use warnings;
use Math::Combinatorics;

my @zeichen = ('A'..'C');
my $count   = 3;
my %permute;

my $combo   = Math::Combinatorics->new( count => $count,
                                       data  => [(@zeichen) x $count]);

while(my @combo = $combo->next_combination){
   $permute{join(' ', @combo)} = 1;
}

print join "\n",keys %permute;