RosettaCodeData/Task/100-doors/Prolog/100-doors-2.pro
2017-09-25 22:28:19 +02:00

34 lines
642 B
Prolog

doors_unoptimized(N) :-
length(L, N),
maplist(init, L),
doors(N, N, L, L1),
affiche(N, L1).
init(close).
doors(Max, 1, L, L1) :-
!,
inverse(1, 1, Max, L, L1).
doors(Max, N, L, L1) :-
N1 is N - 1,
doors(Max, N1, L, L2),
inverse(N, 1, Max, L2, L1).
inverse(N, Max, Max, [V], [V1]) :-
!,
0 =:= Max mod N -> inverse(V, V1); V1 = V.
inverse(N, M, Max, [V|T], [V1|T1]) :-
M1 is M+1,
inverse(N, M1, Max, T, T1),
( 0 =:= M mod N -> inverse(V, V1); V1 = V).
inverse(open, close).
inverse(close, open).
affiche(N, L) :-
forall(between(1, N, I),
( nth1(I, L, open) -> format('Door ~w is open.~n', [I]); true)).