comment on

sub gen_idx_powerset (Int $size is copy) returns Array {
    my @c = ([]);
    for 0 .. $size-1 -> $i {
        push @c, (map { [@$_, $i] }, @c);
    }
    return @c;
}

# Fifteens
$score += 2 * grep {
    15 == [+]( @hand[@$_]>>.<val> )
}, gen_idx_powerset( +@hand );
[download]

Notes:

I'm still trying to figure out a way of generating the powerset of indices without needing the for-loop, but it's an iterative process that needs the list from the prior iteration to work. So, I'm not sure if that's possible.
I don't know if the parentheses around @hand[@$_]>>.<val> are needed.
I don't know if it's @hand[@$_] or @hand[$_]. I hope it's the former, but there's some weird stuff about promoting array references in a DWIM-ish fashion which I haven't understood. So, you may be able to golf another character.
gen_idx_powerset() will return the powerset with the empty set first. Add a reverse if you want to use that as a for-loop. It should also be trivial to convert that into an iterator with gather-take or some similar construct.
Yes, gen_idx_powerset() is a very elegant algorithm when done recursively. That's not how it came to me at midnight last night, though. I don't think that the tail-call optimization in P6 will help much, and the recursion isn't parallelizable because of the dependence on the prior iteration's results.
```
sub gen_idx_powerset( Int $i is copy ) {
    return [] unless $i > 0;
    return (
        gen_idx_powerset( $i - 1 ),
        (map { [@$_, $i] }, gen_idx_powerset( $i - 1 ) ),
    );
}
[download]
```

In general, if you think something isn't in Perl, try it out, because it usually is. :-)
"What is the sound of Perl? Is it not the sound of a wall that people have stopped banging their heads against?"

In reply to Re^3: Perl6 Contest: Test your Skills by dragonchild
in thread Perl6 Contest: Test your Skills by Limbic~Region

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		`&`
	<		`<`
	>		`>`
	[		`[`
	]		`]`

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.