use strict;
use warnings;
use Data::Dump qw/pp dd/;


my $goal = [3,1];
my ($gl,$gr) = @$goal;

my @results;

pathfinder( [0,0,"start"] );                      # start

pp \@$_ for @results;


sub pathfinder {
    my ( $last ) = @_;

    my ( $l, $r ) = @$last ;

    if ( $gl == $l ) {
        if ($gr == $r) {
            push @results,[ reverse @_];
        } else {
            warn "wrong",pp [reverse @_];
            return
        }

    }


    # left
    pathfinder( [$l+1,$r  ,"left"], @_ ) if $l < $gl - ($gr - $r);

    # right
    pathfinder( [$l+1,$r+1,"right"], @_ ) if $r < $gr;
}