I came up with the below. Basically my intention was to avoid copying the arrays unless necessary.
#!/usr/bin/perl
use strict;
use warnings;
my @list = (1 .. 5);
my $take = 2;
comb_demerphq(\@list, $take, []);
sub comb_demerphq {
my ($items,$group,$list)=@_;
return _comb_demerphq([ @{ $items||[] } ],$ group, [ @{ $list||[]
+} ] );
}
sub _comb_demerphq {
my ($items,$group,$list) = @_;
unless ($group) {
print "@$list\n";
} else {
my @newlist = (@$list,undef);
while (@$items) {
$newlist[-1]=shift (@$items);
_comb_demerphq([@$items], $group - 1, \@newlist);
}
}
}
But i suspect that there are still better ways to improve this by using a different algorithm. Not sure what it is though.
---
demerphq
<Elian> And I do take a kind of perverse pleasure in having an OO assembly language...
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