You can't get there from here

NP

Note that NP problems can be efficiently solved by people who are very lucky guessers:

        sub trade {
          my ($items, $sizes, $values, $max_size, $budget) = @_;
          my $cargo = lucky_guess($items);
          return is_solution($cargo, @_) ? $cargo : undef;
        }

Also by people who can do many tasks at once:

        use Quantum::Superpositions
            UNARY_LOGICAL => ['main::is_solution'];

        sub trade {
          my ($items, $sizes, $values, $max_size, $budget) = @_;
          my $cargo = any(all_selections($items));
          my $solutions = is_solution($cargo, @_); # "In constant time!"
          my ($a_solution) = eigenstates(is_solution($cargo, @_));
          return $a_solution;
        }