sub possible {
    my ( $tiles_ref, $dict_ref ) = @_;

    my @out;
    my %tile_count;
    $tile_count{$_}++ for @{$tiles_ref};
    my $longest_word = scalar @{$tiles_ref};
  WORD:
    foreach my $word ( keys %{$dict_ref} ) {
        next WORD if length $word > $longest_word;
        foreach my $letter ( keys %{$dict_ref->{$word}} ) {
            next WORD if ! defined $tile_count{$letter};
            next WORD if $dict_ref->{$word}{$letter} > $tile_count{$letter};
        }
        push @out, $word;
    }

    return @out;
}

# example:
use Data::Dumper;
print Dumper( possible( [ qw( a b c d e ) ], read_dict() ) );