Data commit

Task/Power-set/Perl/power-set-1.pl

@@ -0,0 +1,8 @@
+use Algorithm::Combinatorics "subsets";
+my @S = ("a","b","c");
+my @PS;
+my $iter = subsets(\@S);
+while (my $p = $iter->next) {
+  push @PS, "[@$p]"
+}
+say join("  ",@PS);

Task/Power-set/Perl/power-set-10.pl

@@ -0,0 +1,8 @@
+my @set = (1, 2, 3);
+my @powerset = powerset(@set);
+
+sub set_to_string {
+    "{" . join(", ", map { ref $_ ? set_to_string(@$_) : $_ } @_) . "}"
+}
+
+print set_to_string(@powerset), "\n";

Task/Power-set/Perl/power-set-11.pl

@@ -0,0 +1,21 @@
+use strict;
+use warnings;
+sub powerset :prototype(&@) {
+    my $callback = shift;
+    my $bitmask = '';
+    my $bytes = @_/8;
+    {
+       my @indices = grep vec($bitmask, $_, 1), 0..$#_;
+       $callback->( @_[@indices] );
+       ++vec($bitmask, $_, 8) and last for 0 .. $bytes;
+       redo if @indices != @_;
+    }
+}
+
+print "powerset of empty set:\n";
+powerset { print "[@_]\n" };
+print "powerset of set {1,2,3,4}:\n";
+powerset { print "[@_]\n" } 1..4;
+my $i = 0;
+powerset { ++$i } 1..9;
+print "The powerset of a nine element set contains $i elements.\n";

Task/Power-set/Perl/power-set-2.pl

@@ -0,0 +1,4 @@
+use ntheory "forcomb";
+my @S = qw/a b c/;
+forcomb { print "[@S[@_]]  " } scalar(@S);
+print "\n";

Task/Power-set/Perl/power-set-3.pl

@@ -0,0 +1,7 @@
+use ntheory "forcomb";
+my @S = qw/a b c/;
+for $k (0..@S) {
+  # Iterate over each $#S+1,$k combination.
+  forcomb { print "[@S[@_]]  " } @S,$k;
+}
+print "\n";

Task/Power-set/Perl/power-set-4.pl

@@ -0,0 +1,4 @@
+use ntheory "vecextract";
+my @S = qw/a b c/;
+my @PS = map { "[".join(" ",vecextract(\@S,$_))."]" } 0..2**scalar(@S)-1;
+say join("  ",@PS);

Task/Power-set/Perl/power-set-5.pl

@@ -0,0 +1,14 @@
+use Set::Object qw(set);
+
+sub powerset {
+    my $p = Set::Object->new( set() );
+    foreach my $i (shift->elements) {
+        $p->insert( map { set($_->elements, $i) } $p->elements );
+    }
+    return $p;
+}
+
+my $set = set(1, 2, 3);
+my $powerset = powerset($set);
+
+print $powerset->as_string, "\n";

Task/Power-set/Perl/power-set-6.pl

@@ -0,0 +1,6 @@
+package Set {
+    sub new       { bless { map {$_ => undef} @_[1..$#_] }, shift; }
+    sub elements  { sort keys %{shift()} }
+    sub as_string { 'Set(' . join(' ', sort keys %{shift()}) . ')' }
+    # ...more set methods could be defined here...
+}

Task/Power-set/Perl/power-set-7.pl

@@ -0,0 +1,11 @@
+use List::Util qw(reduce);
+
+sub powerset {
+    @{( reduce { [@$a, map { Set->new($_->elements, $b) } @$a ] }
+               [Set->new()], shift->elements )};
+}
+
+my $set = Set->new(1, 2, 3);
+my @subsets = powerset($set);
+
+print $_->as_string, "\n" for @subsets;

Task/Power-set/Perl/power-set-8.pl

@@ -0,0 +1,3 @@
+sub powerset {
+    @_ ? map { $_, [$_[0], @$_] } powerset(@_[1..$#_]) : [];
+}

Task/Power-set/Perl/power-set-9.pl

@@ -0,0 +1,5 @@
+use List::Util qw(reduce);
+
+sub powerset {
+    @{( reduce { [@$a, map([@$_, $b], @$a)] } [[]], @_ )}
+}