230 lines
6.4 KiB
Mathematica
230 lines
6.4 KiB
Mathematica
:- module day12.
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:- interface.
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:- import_module basics.
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:- pred run(part::in, lines::in, answer::out) is cc_multi.
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:- implementation.
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:- import_module int.
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:- import_module char.
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:- import_module string.
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:- import_module list.
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:- import_module array2d.
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:- type point == {int, int}.
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:- type grid ---> g(array :: array2d(char), start :: point, end :: point).
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:- pred grid(lines::in, grid::out) is semidet.
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grid(Lines, g(Arr, {SX, SY}, {EX, EY})) :-
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Arr = from_lists(map(to_char_list, Lines)),
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find(Arr, 'S', SX, SY),
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find(Arr, 'E', EX, EY).
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:- pred find_from(array2d(T)::in, T::in, int::in, int::in, int::out, int::out)
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is semidet.
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find_from(Arr, A, X1, Y1, X2, Y2) :-
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bounds(Arr, W, H),
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Y1 < H,
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(if X1 < W then
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B = Arr^elem(X1, Y1),
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(if A = B then X2 = X1, Y2 = Y1
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else find_from(Arr, A, X1+1, Y1, X2, Y2))
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else
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find_from(Arr, A, 0, Y1+1, X2, Y2)).
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:- pred find(array2d(T)::in, T::in, int::out, int::out) is semidet.
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find(Arr, A, X, Y) :- find_from(Arr, A, 0, 0, X, Y).
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:- func get(grid, point) = char.
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get(G, {X, Y}) = G^array^elem(X, Y).
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:- func height(char) = int.
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height(C) = I :-
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if C = 'S' then I = 0
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else if C = 'E' then I = 25
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else I = to_int(C) - to_int('a').
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:- func height(grid, point) = int.
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height(G, P) = height(get(G, P)).
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:- pred adj_point(point::in, point::out) is multi.
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adj_point({X, Y}, {X+1, Y}).
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adj_point({X, Y}, {X-1, Y}).
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adj_point({X, Y}, {X, Y+1}).
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adj_point({X, Y}, {X, Y-1}).
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:- pred adj(grid::in, point::in, point::out) is nondet.
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adj(G, P, Q) :-
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adj_point(P, Q), in_bounds(G, Q),
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abs(height(G, P) - height(G, Q)) =< 1.
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:- pred in_bounds(grid::in, point::in) is semidet.
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in_bounds(G, {X, Y}) :-
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bounds(G^array, W, H),
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0 =< X, X < W,
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0 =< Y, Y < H.
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:- pred index(grid::in, point::out) is nondet.
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index(G, {I, J}) :-
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bounds(G^array, W, H),
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nondet_int_in_range(0, W-1, I),
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nondet_int_in_range(0, H-1, J).
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:- type path == list(point).
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:- type distance ---> i(int); inf.
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:- import_module solutions.
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:- import_module map.
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:- type pm == map(point, point).
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:- type nq ---> nq(pq, dm).
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:- type dm == map(point, distance).
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:- type pq == list({point, distance}).
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:- pred remove_min(point::out, distance::out, pq::in, pq::out) is semidet.
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remove_min(X, D, [{X0, D0} | PQ0], PQ) :-
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if
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remove_min(X1, D1, PQ0, PQ1),
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D1 @< D0
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then
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X = X1, D = D1,
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PQ = [{X0, D0} | PQ1]
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else
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X = X0, D = D0,
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PQ = PQ0.
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:- pred seen(nq::in, point::in) is semidet.
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seen(nq(_, S), X) :- contains(S, X).
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:- pred next(point::out, distance::out, nq::in, nq::out) is semidet.
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next(X, D, nq(!.Q, !.S), nq(!:Q, !:S)) :-
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remove_min(X, D, !Q), set(X, D, !S).
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:- pred set_distance_pq(point::in, distance::in, pq::in, pq::out) is det.
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set_distance_pq(_, _, [], []).
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set_distance_pq(X, D, [{Y, E} | Xs], Zs) :-
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if X = Y then
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Zs = [{X, D} | Xs]
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else
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set_distance_pq(X, D, Xs, Xs2),
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Zs = [{Y, E} | Xs2].
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:- pred set_distance(point::in, distance::in, nq::in, nq::out) is det.
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set_distance(X, D, nq(!.Q, !.S), nq(!:Q, !:S)) :-
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set_distance_pq(X, D, !Q),
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(if contains(!.S, X) then det_update(X, D, !S) else true).
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:- func get_distance(point, pq, dm) = distance.
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:- mode get_distance(in, in, in) = out is semidet.
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get_distance(X, [], S) = search(S, X).
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get_distance(X, [{Y, D} | Xs], S) = D1 :-
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if X = Y then D1 = D else D1 = get_distance(X, Xs, S).
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:- func get_distance(point, nq) = distance.
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:- mode get_distance(in, in) = out is semidet.
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get_distance(X, nq(Q, S)) = get_distance(X, Q, S).
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:- pred insert_init(point::in, point::in, pq::in, pq::out) is det.
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insert_init(From, X, !Queue) :-
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(if X = From then D = i(0) else D = inf),
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cons({X, D}, !Queue).
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:- pred init_queue(grid::in, point::in, nq::out) is det.
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init_queue(G, From, nq(Q, init)) :-
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aggregate(index(G), insert_init(From), [], Q).
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:- pred get_path_rev(pm::in, point::in, point::in, path::out) is det.
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get_path_rev(Map, From, To, Path) :-
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if From = To then
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Path = []
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else if search(Map, To, Prev) then
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get_path_rev(Map, From, Prev, Tail),
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Path = [To | Tail]
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else
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To = {X, Y},
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die("no predecessor for {%d, %d}", [i(X), i(Y)]).
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:- pred get_path(pm::in, point::in, point::in, path::out) is det.
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get_path(Map, From, To, reverse(Path)) :- get_path_rev(Map, From, To, Path).
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:- func incr(distance) = distance.
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incr(inf) = inf.
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incr(i(N)) = i(N + 1).
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:- pred neighbours(grid::in, point::in, nq::in, point::out) is nondet.
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neighbours(G, Point, Queue, N) :-
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adj(G, Point, N),
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not seen(Queue, N).
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:- pred path(grid::in, point::in, point::in, path::out,
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nq::in, nq::out, pm::in, pm::out) is semidet.
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path(G, From, To, Path, !Queue, !Prev) :-
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next(Point, Distance, !Queue),
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Distance = inf => die("ow"),
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Neighs = solutions(neighbours(G, Point, !.Queue)),
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foldl2(pred(Neigh::in, % 🐴
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!.Queue::in, !:Queue::out,
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!.Prev::in, !:Prev::out) is det :- (
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Alt = incr(Distance),
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(if Alt @< get_distance(Neigh, !.Queue) then
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set_distance(Neigh, Alt, !Queue),
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set(Neigh, Point, !Prev)
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else true)),
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Neighs, !Queue, !Prev),
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(if Point = To then
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get_path(!.Prev, From, To, Path)
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else
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path(G, From, To, Path, !Queue, !Prev)).
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:- pred path(grid::in, point::in, point::in, path::out) is semidet.
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path(G, From, To, Path) :-
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init_queue(G, From, Queue),
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path(G, From, To, Path, Queue, _, init, _).
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:- pred path(grid::in, path::out) is semidet.
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path(G, Path) :- path(G, G^start, G^end, Path).
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run(_, Lines, Out) :-
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if
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grid(Lines, G),
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init_queue(G, G^start, Q),
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path(G, G^start, G^end, Path, Q, nq(Q1, S1), init, Prev)
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then
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Out = 'new other'({"RESULT", length(Path):int,
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"G", G, "Path", Path,
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"Q1", Q1,
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"S1", to_assoc_list(S1):list(_),
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"Prev", to_assoc_list(Prev):list(_)})
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else
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die("bad input").
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/* omg could u imagine if this had worked tho
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:- pragma memo(path/5, [fast_loose]).
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:- pred path(grid::in, point::in, point::in, path::in, int::out)
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is nondet.
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path(G, P, P, _, 0).
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path(G, P, Q, Seen, Len + 1) :-
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adj(G, P, P1),
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not member(P1, Seen),
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path(G, P1, Q, [P|Seen], Len).
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:- pred path(grid::in, point::in, point::in, int::out) is nondet.
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path(G, P, Q, Len) :- path(G, P, Q, [], Len).
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:- import_module solutions.
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run(_, Lines, Out) :-
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if grid(Lines, G) then
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solutions(path(G, G^start, G^end), Paths),
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Out = int(det_head(Paths))
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else
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die("bad input").
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*/
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