March 2014 update

Task/Power-set/C/power-set.c

@@ -0,0 +1,31 @@
+#include <stdio.h>
+
+struct node {
+	char *s;
+	struct node* prev;
+};
+
+void powerset(char **v, int n, struct node *up)
+{
+	struct node me;
+
+	if (!n) {
+		putchar('[');
+		while (up) {
+			printf(" %s", up->s);
+			up = up->prev;
+		}
+		puts(" ]");
+	} else {
+		me.s = *v;
+		me.prev = up;
+		powerset(v + 1, n - 1, up);
+		powerset(v + 1, n - 1, &me);
+	}
+}
+
+int main(int argc, char **argv)
+{
+	powerset(argv + 1, argc - 1, 0);
+	return 0;
+}

Task/Power-set/Clojure/power-set-1.clj

@@ -1,4 +1,4 @@
-(use '[clojure.contrib.combinatorics :only [subsets] ])
+(use '[clojure.math.combinatorics :only [subsets] ])
 
 (def S #{1 2 3 4})
 

Task/Power-set/Clojure/power-set-2.clj

@@ -0,0 +1,7 @@
+(defn powerset
+  [coll]
+  (reduce (fn [a x]
+            (set (concat a (map #(set (concat #{x} %)) a))))
+          #{#{}} coll))
+
+(powerset #{1 2 3})

Task/Power-set/Clojure/power-set-3.clj

@@ -0,0 +1 @@
+#{#{} #{1} #{2} #{1 2} #{3} #{1 3} #{2 3} #{1 2 3}}

Task/Power-set/D/power-set-2.d

@@ -1,4 +1,4 @@
-auto powerSet(T)(T[] xs) {
+auto powerSet(T)(T[] xs) pure nothrow {
     auto output = new T[xs.length];
     immutable size_t len = 1U << xs.length;
 

Task/Power-set/Maple/power-set.maple

@@ -0,0 +1,3 @@
+with(combinat):
+
+powerset({1,2,3,4});

Task/Power-set/Objective-C/power-set.m

@@ -7,11 +7,10 @@
 		NSMutableArray *subset = [[NSMutableArray alloc] init];
 		for (int itemIndex = 0; itemIndex < array.count; itemIndex++) {
 			if((subsetIndex >> itemIndex) & 0x1) {
-				[subset addObject:[array objectAtIndex:itemIndex]];
+				[subset addObject:array[itemIndex]];
 			}
 		}		
 		[subsets addObject:subset];
-		[subset release];
 	}
 	return subsets;
 }

Task/Power-set/Perl-6/power-set-1.pl6

@@ -0,0 +1,2 @@
+sub powerset(Set $s) { $s.combinations.map(*.Set).Set }
+say powerset set <a b c d>;

Task/Power-set/Perl-6/power-set-2.pl6

@@ -0,0 +1 @@
+.say for <a b c d>.combinations

Task/Power-set/Perl-6/power-set.pl6

@@ -1,3 +0,0 @@
-sub powerset ( *@list ) {
-    reduce( -> @L, $n { [ @L, @L.map({[ $_.list, $n ]}) ] }, [[]], @list );
-}

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

@@ -1 +1,14 @@
-sub p{@_?map{$_,[$_[0],@$_]}p(@_[1..$#_]):[]}
+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-2.pl

@@ -1,4 +1,6 @@
-use List::Util qw(reduce);
-sub powerset {
-  @{ (reduce { [@$a, map([@$_, $b], @$a)] } [[]], @_) }
+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-3.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-4.pl

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

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

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

Task/Power-set/Perl/power-set-6.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/Prolog/power-set-1.pro

@@ -1,9 +1,6 @@
-power_set(T, PS) :-
-	bagof(PS1, power_set(T, [], PS1), PS).
+powerset(X,Y) :- bagof( S, subseq(S,X), Y).
 
-power_set(T, PS, PS1) :-
-	select(E, T, T1), !,
-	append(PS, [E], PST),
-	( PST = PS1;  power_set(T1, PS, PS1);  power_set(T1, PST, PS1)).
-
-power_set([], [], []).
+subseq( [], []).
+subseq( [], [_|_]).
+subseq( [X|Xs], [X|Ys] ) :- subseq(Xs, Ys).
+subseq( [X|Xs], [_|Ys] ) :- append(_, [X|Zs], Ys), subseq(Xs, Zs).

Task/Power-set/Prolog/power-set-2.pro

@@ -1,18 +1,5 @@
-:- use_module(library(chr)).
-
-:- chr_constraint chr_power_set/2, chr_power_set/1, clean/0.
-
-clean @ clean \ chr_power_set(_) <=> true.
-clean @ clean <=> true.
-
-only_one @ chr_power_set(A) \ chr_power_set(A) <=> true.
-
-
-creation @ chr_power_set([H | T], A) <=>
-           append(A, [H], B),
-	   chr_power_set(T, A),
-           chr_power_set(T, B),
-	   chr_power_set(B).
-
-
-empty_element @ chr_power_set([], _) <=> chr_power_set([]).
+power_set( [], [[]]).
+power_set( [X|Xs], PS) :-
+  power_set(Xs, PS1),
+  maplist( append([X]), PS1, PS2 ), % i.e. prepend X to each PS1
+  append(PS1, PS2, PS).

Task/Power-set/Prolog/power-set-3.pro

@@ -0,0 +1,18 @@
+:- use_module(library(chr)).
+
+:- chr_constraint chr_power_set/2, chr_power_set/1, clean/0.
+
+clean @ clean \ chr_power_set(_) <=> true.
+clean @ clean <=> true.
+
+only_one @ chr_power_set(A) \ chr_power_set(A) <=> true.
+
+
+creation @ chr_power_set([H | T], A) <=>
+           append(A, [H], B),
+	   chr_power_set(T, A),
+           chr_power_set(T, B),
+	   chr_power_set(B).
+
+
+empty_element @ chr_power_set([], _) <=> chr_power_set([]).

Task/Power-set/Python/power-set-5.py

@@ -0,0 +1,26 @@
+>>> from pprint import pprint as pp
+>>> from itertools import chain, combinations
+>>>
+>>> def powerset(iterable):
+    "powerset([1,2,3]) --> () (1,) (2,) (3,) (1,2) (1,3) (2,3) (1,2,3)"
+    s = list(iterable)
+    return chain.from_iterable(combinations(s, r) for r in range(len(s)+1))
+
+>>> pp(set(powerset({1,2,3,4})))
+{(),
+ (1,),
+ (1, 2),
+ (1, 2, 3),
+ (1, 2, 3, 4),
+ (1, 2, 4),
+ (1, 3),
+ (1, 3, 4),
+ (1, 4),
+ (2,),
+ (2, 3),
+ (2, 3, 4),
+ (2, 4),
+ (3,),
+ (3, 4),
+ (4,)}
+>>>

Task/Power-set/TXR/power-set-1.txr

@@ -0,0 +1,4 @@
+(defun power-set (s)
+ (reduce-right
+   (op append (mapcar (op cons @@1) @2) @2)
+   s '(())))

Task/Power-set/TXR/power-set-2.txr

@@ -0,0 +1,10 @@
+@(do (defun power-set (s)
+       (reduce-right
+         (op append (mapcar (op cons @@1) @2) @2)
+         s '(()))))
+@(bind pset @(power-set *args*))
+@(output)
+@  (repeat)
+{@(rep)@pset, @(last)@pset@(empty)@(end)}
+@  (end)
+@(end)

Task/Power-set/TXR/power-set-3.txr

@@ -0,0 +1,7 @@
+@(do (defun power-set (s)
+       (reduce-right
+         (op append (mapcar (op cons @@1) @2) @2)
+         s '(())))
+     (prinl (power-set "abc"))
+     (prinl (power-set ""))
+     (prinl (power-set #(1 2 3))))

Task/Power-set/TXR/power-set.txr

@@ -1,14 +0,0 @@
-@(next :args)
-@(do (defun power-set (s)
-       (reduce-right
-         (lambda (item ps)
-           (append (mapcar (lambda (e) (cons item e)) ps) ps)) s '(()) nil)))
-@(collect :vars (arg))
-@arg
-@(end)
-@(bind pset @(power-set arg))
-@(output)
-@  (repeat)
-{@(rep)@pset, @(last)@pset@(empty)@(end)}
-@  (end)
-@(end)