#!/usr/bin/perl

use warnings;
use strict;
use feature 'say';
use Data::Dumper;
$Data::Dumper::Indent = 0;

my $n = 3;
my $k = 2;

my @todo_list = ([ 0, [] ]);

while (@todo_list) {
    my $todo = pop @todo_list;
    my $local_n = $todo->[0] +1;
    for my $curr_k (1..$k) {
        if ($local_n == $n) {
            print "x ";
            print Dumper(\@todo_list);
            print "   ->   ";
            say join(', ', @{$todo->[1]}, $curr_k);
        }
        else {
            push @todo_list, [ $local_n, [ @{$todo->[1]}, $curr_k ] ];
            print Dumper(\@todo_list);
            print "   :   ";
            say join(', ', @{$todo->[1]}, $curr_k);
        }
    }
}