June 2018 Update

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

@@ -1,9 +1,6 @@
 (defn powerset [coll]
   (reduce (fn [a x]
-            (->> a
-                 (map #(set (concat #{x} %)))
-                 (concat a)
-                 set))
+            (into a (map #(conj % x)) a))
           #{#{}} coll))
 
 (powerset #{1 2 3})

Task/Power-set/Go/power-set.go

@@ -1,9 +1,9 @@
 package main
 
 import (
-    "bytes"
     "fmt"
     "strconv"
+    "strings"
 )
 
 // types needed to implement general purpose sets are element and set
@@ -85,7 +85,7 @@ func (s set) String() string {
     if len(s) == 0 {
         return "∅"
     }
-    var buf bytes.Buffer
+    var buf strings.Builder
     buf.WriteRune('{')
     for i, e := range s {
         if i > 0 {
@@ -104,7 +104,7 @@ func (s set) powerSet() set {
         var u set
         for _, er := range r {
             er := er.(set)
-           u = append(u, append(er[:len(er):len(er)], es))
+            u = append(u, append(er[:len(er):len(er)], es))
         }
         r = append(r, u...)
     }

Task/Power-set/PARI-GP/power-set-2.pari

@@ -0,0 +1,2 @@
+S=["a","b","c"]
+forsubset(#S,s,print1(vecextract(S,s)"  "))

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

@@ -1,21 +1,8 @@
-use strict;
-use warnings;
-sub powerset(&@) {
-    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 != @_;
-    }
+my @set = (1, 2, 3);
+my @powerset = powerset(@set);
+
+sub set_to_string {
+    "{" . join(", ", map { ref $_ ? set_to_string(@$_) : $_ } @_) . "}"
 }
 
-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";
+print set_to_string(@powerset), "\n";

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

@@ -0,0 +1,21 @@
+use strict;
+use warnings;
+sub powerset(&@) {
+    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

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

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

@@ -1,5 +1,5 @@
 use ntheory "forcomb";
-my @S=("a","b","c");
+my @S = qw/a b c/;
 for $k (0..@S) {
   # Iterate over each $#S+1,$k combination.
   forcomb { print "[@S[@_]]  " } @S,$k;

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

@@ -1,14 +1,4 @@
-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 $powerset->as_string, "\n";
+use ntheory "vecextract";
+my @S = qw/a b c/;
+my @PS = map { "[".join(" ",vecextract(\@S,$_))."]" } 0..2**scalar(@S)-1;
+say join("  ",@PS);

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

@@ -1,6 +1,14 @@
-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...
+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

@@ -1,11 +1,6 @@
-use List::Util qw(reduce);
-
-sub powerset {
-    @{( reduce { [@$a, map { Set->new($_->elements, $b) } @$a ] }
-               [Set->new()], shift->elements )};
+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...
 }
-
-my $set = Set->new(1, 2, 3);
-my @subsets = powerset($set);
-
-print $_->as_string, "\n" for @subsets;

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

@@ -1,3 +1,11 @@
+use List::Util qw(reduce);
+
 sub powerset {
-    @_ ? map { $_, [$_[0], @$_] } powerset(@_[1..$#_]) : [];
+    @{( 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

@@ -1,5 +1,3 @@
-use List::Util qw(reduce);
-
 sub powerset {
-    @{( reduce { [@$a, map([@$_, $b], @$a)] } [[]], @_ )}
+    @_ ? map { $_, [$_[0], @$_] } powerset(@_[1..$#_]) : [];
 }

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

@@ -1,8 +1,5 @@
-my @set = (1, 2, 3);
-my @powerset = powerset(@set);
+use List::Util qw(reduce);
 
-sub set_to_string {
-    "{" . join(", ", map { ref $_ ? set_to_string(@$_) : $_ } @_) . "}"
+sub powerset {
+    @{( reduce { [@$a, map([@$_, $b], @$a)] } [[]], @_ )}
 }
-
-print set_to_string(@powerset), "\n";

Task/Power-set/Ring/power-set.ring

@@ -0,0 +1,23 @@
+# Project : Power set
+# Date    : 2018/01/13
+# Author : Gal Zsolt (~ CalmoSoft ~)
+# Email   : <calmosoft@gmail.com>
+
+list = ["1", "2", "3", "4"]
+see powerset(list)
+
+func powerset(list)
+        s = "{"
+        for i = 1 to (2 << len(list)) - 1 step 2
+             s = s + "{"
+             for j = 1 to len(list)
+                  if i & (1 << j)
+                     s = s + list[j] + ","
+                  ok
+             next
+             if right(s,1) = ","
+                s = left(s,len(s)-1)
+             ok
+             s = s + "},"
+        next
+        return left(s,len(s)-1) + "}"

Task/Power-set/Swift/power-set-1.swift

@@ -0,0 +1,15 @@
+func powersetFrom<T>(_ elements: Set<T>) -> Set<Set<T>> {
+  guard elements.count > 0 else {
+    return [[]]
+  }
+  var powerset: Set<Set<T>> = [[]]
+  for element in elements {
+    for subset in powerset {
+      powerset.insert(subset.union([element]))
+    }
+  }
+  return powerset
+}
+
+// Example:
+powersetFrom([1, 2, 4])

Task/Power-set/Swift/power-set-2.swift

@@ -0,0 +1,2 @@
+//Example:
+powersetFrom(["a", "b", "d"])