Re: Re (tilly) 2: (Golf as well): List of Partitions

[danger]

Hmm, and we can shave that down to 71 chars:

sub P{
[@_],map{my$i=$_;grep{!grep$_>$i,@$_}map[$i,@$_],P($_[0]-$i)}1..$_[0]-
+1
}

[tilly]

Nice, now slimed down to 64 on the knowledge that the partitions are always sorted from largest number to smallest...

sub P{
[@_],map{my$i=$_;map$$_[0]>$i?():[$i,@$_],P($_[0]-$i)}1..$_[0]-1
}

UPDATE
Saved an additional char because my map could be commified.

UPDATE 2
Scraping the barrel for 61:

sub P{
my$i;[@_],map{map$$_[0]>$i?():[$i,@$_],P($_[0]-++$i)}2..$_[0]
}

[jynx]

Tilly, i would say something, but it would sound clunky compared to the beautiful code above. It would be nice if i could ++ you more than once for that snippet.

One question though, what's commified? i'm not sure if i've ever heard the term...

jynx

[tilly]

Here is what I mean by commified. Consider the following 2 versions of the same map statement:

...map{"@$_\n"}@a...
...map"@$_\n",@a...

The first form is more general, you can put more complex logic inside the block. The second form replaces the block with a comma and shaves a character. Often you can shave a few characters off of someone's solution by seeing that a few map's or grep's can switch over to the version with the comma.

Sometimes it is not obvious that you can. So sometimes I just have to try it out. As in the case:

...map{$$_[0]>$i?():[$i,@$_]}P($n-$i)...
...map$$_[0]>$i?():[$i,@$_],P($n-$i)...

Incidentally the following version is the same size, but has slightly nicer (IMHO) output:

sub P{
my$i=pop;[$i],map{--$i;map$$_[0]>$i?():[$i,@$_],P($_-1)}2..$i
}