ex5: finish, gather handin.pl

assignment5/handin.pl

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+% task 1
+
+payment(Sum, Coins) :-
+    payment_acc(0, Sum, Coins).
+
+payment_acc(Acc, Sum, []) :-
+    Acc #= Sum.
+
+payment_acc(Acc, Sum, [coin(Count, Value, Available)|Tail]) :-
+    Count in 0..Available,
+    NewAcc #= Acc + Count * Value,
+    payment_acc(NewAcc, Sum, Tail).
+
+% task 2.1
+
+distance(c1, c2, 10, 1). distance(c1, c3, 0, 0). distance(c1, c4, 7, 1).
+distance(c1, c5, 5, 1). distance(c2, c3, 4, 1). distance(c2, c4, 12, 1).
+distance(c2, c5, 20, 1). distance(c3, c4, 0, 0). distance(c3, c5, 0, 0).
+distance(c4, c5, 0, 0). distance(c2, c1, 10, 1). distance(c3, c1, 0, 0).
+distance(c4, c1, 7, 1). distance(c5, c1, 5, 1). distance(c3, c2, 4, 1).
+distance(c4, c2, 12, 1). distance(c5, c2, 20, 1). distance(c4, c3, 0, 0).
+distance(c5, c3, 0, 0). distance(c5, c4, 0, 0).
+
+% arity 4 predicate
+plan(Cabin1, Cabin2, Path, TotalDistance) :-
+    plan(Cabin1, Cabin2, [Cabin1], Path, TotalDistance).
+
+% base case
+plan(Cabin1, Cabin2, Visited, Path, Distance) :-
+    not(Cabin1 = Cabin2),
+    distance(Cabin1, Cabin2, Distance, 1),
+    append(Visited, [Cabin2], Path).
+
+% recursive case
+plan(Cabin1, Cabin2, Visited, Path, TotalDistance) :-
+    not(Cabin1 = Cabin2),
+    distance(Cabin1, CabinX, Distance, 1),
+    \+ member(CabinX, Visited),
+    append(Visited, [CabinX], NewVisited),
+    plan(CabinX, Cabin2, NewVisited, Path, SubDistance),
+    TotalDistance is Distance + SubDistance.
+
+% task 2.2
+
+bestplan(Cabin1, Cabin2, ShortestPath, ShortestDistance) :-
+    findall([Path, Distance], (plan(Cabin1, Cabin2, Path, Distance)), Solutions),
+    sort(2, @=<, Solutions, [ShortestSolution|_]),
+    [ShortestPath, ShortestDistance] = ShortestSolution.