sub greedy_change {
    my $change = shift;
    my $coin_count = 0;
    my @combo;
    my $blah = sub {
                print "Code doesn't get run after once.\n";
                my @lengths = ($_[1]);
                my $new_count = 0;
                $lengths[$_] = $_[$_+1] - $_[$_] for 1..$#denoms;
                $new_count += $lengths[$_]/$denoms[$_] for 0..$#denoms;
                if (!$coin_count or $new_count < $coin_count) {
                    print "$change: $new_count is better than $coin_count\n";
                    $coin_count = $new_count;
                    @combo = @lengths;
                }
    };

    print "Trying to change $change with @denoms...\n";
    print "$expr on $_\n";

    $_ = ('1' x $change);
    if (
        m{^$expr$
            (?{ $blah->(@+) })
        }x)
    {
        print "Matched!\n";
    }
    if ($coin_count) {
        print "C=$coin_count\n";
    }
    else {
        print "No matching combination found\n";
    }
    @combo;
}