tasks a-s

Task/Power-set/Logtalk/power-set-1.logtalk

@@ -0,0 +1,25 @@
+:- object(set).
+
+    :- public(powerset/2).
+
+    powerset(Set, PowerSet) :-
+        reverse(Set, RSet),
+        powerset_1(RSet, [[]], PowerSet).
+
+    powerset_1([], PowerSet, PowerSet).
+    powerset_1([X| Xs], Yss0, Yss) :-
+        powerset_2(Yss0, X, Yss1),
+        powerset_1(Xs, Yss1, Yss).
+
+    powerset_2([], _, []).
+    powerset_2([Zs| Zss], X, [Zs, [X| Zs]| Yss]) :-
+        powerset_2(Zss, X, Yss).
+
+    reverse(List, Reversed) :-
+        reverse(List, [], Reversed).
+
+    reverse([], Reversed, Reversed).
+    reverse([Head| Tail], List, Reversed) :-
+        reverse(Tail, [Head| List], Reversed).
+
+:- end_object.

Task/Power-set/Logtalk/power-set-2.logtalk

@@ -0,0 +1,4 @@
+| ?- set::powerset([1, 2, 3, 4], PowerSet).
+
+PowerSet = [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3],[4],[1,4],[2,4],[1,2,4],[3,4],[1,3,4],[2,3,4],[1,2,3,4]]
+yes