92 lines
3.1 KiB
Prolog
92 lines
3.1 KiB
Prolog
:- use_module(library(pio)).
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:- use_module(library(dcg/basics)).
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:- initialization(main, main).
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% :- table cost/3.
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% :- table to_key/3.
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main([FileName|_]) :-
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input(FileName, Map),
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length(Map, EndXx), EndX is EndXx - 1,
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Start1 = 0-0-horz, Start2 = 0-0-vert,
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to_key(Start1, K1), to_key(Start2, K2), Costs = cost{}.put(K1, 0).put(K2, 0),
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Map = [Row0|_], length(Row0, EndYx), EndY is EndYx - 1,
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heur(0-0, EndX-EndY, Heur0),
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list_to_heap([Heur0-Start1, Heur0-Start2], Queue),
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astar(Map, Costs, Queue, EndX-EndY, N),
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write(N), nl.
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astar(_Map, Costs, PQueue, DestX-DestY, N) :-
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get_from_heap(PQueue, _, X-Y-From, _), X = DestX, Y = DestY,
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to_key(DestX-DestY-From, FromKey), N = Costs.FromKey, !.
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astar(Map, Gs, PQueue, DestX-DestY, N) :-
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get_from_heap(PQueue, _, X-Y-From, PQueueAfterPop),
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to_key(X-Y-From, CurrentKey), CurrentG = Gs.CurrentKey,
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findall(To-Cost, next(Map, X-Y-From, To, Cost), Neighbors),
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foldl(add_neighbor(CurrentG, DestX, DestY),
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Neighbors, PQueueAfterPop-Gs, NewPQueue-NewGs),
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astar(Map, NewGs, NewPQueue, DestX-DestY, N).
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add_neighbor(CurrentG, DestX, DestY, (X-Y-Dir)-Cost, HeapIn-GsIn, HeapOut-GsOut) :-
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NewGCandidate is CurrentG + Cost,
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to_key(X-Y-Dir, Key), ExistingG = GsIn.get(Key, 9999999),
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( NewGCandidate < ExistingG
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-> NewG = NewGCandidate, GsOut = GsIn.put(Key, NewG),
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heur(X-Y, DestX-DestY, Heur), Weight is NewG + Heur,
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( get_from_heap(HeapIn, _, X-Y-Dir, _), HeapOut = HeapIn
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; add_to_heap(HeapIn, Weight, X-Y-Dir, HeapOut)
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)
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; GsOut = GsIn, HeapOut = HeapIn
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).
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to_key(X-Y-horz, Key) :- Key is 0 + Y*10 + X* 10000.
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to_key(X-Y-vert, Key) :- Key is 1 + Y*10 + X* 10000.
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next(Map, X-Y-horz, NextX-Y-vert, Cost) :-
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LowX1 is X - 10, HighX1 is X - 4,
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LowX2 is X + 4, HighX2 is X + 10,
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(between(LowX1, HighX1, NextX); between(LowX2, HighX2, NextX)),
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vert(Map, X-Y, NextX, Cost).
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next(Map, X-Y-vert, X-NextY-horz, Cost) :-
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LowY1 is Y - 10, HighY1 is Y - 4,
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LowY2 is Y + 4, HighY2 is Y + 10,
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(between(LowY1, HighY1, NextY); between(LowY2, HighY2, NextY)),
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horz(Map, X-Y, NextY, Cost).
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vert(Map, X-Y, NextX, Cost) :-
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cost(Map, NextX-Y, _),
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findall(
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Ci,
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( (X < NextX -> between(X, NextX, Xi); between(NextX, X, Xi)),
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Xi =\= X,
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cost(Map, Xi-Y, Ci)),
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Costs),
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sum_list(Costs, Cost).
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% Cost = Costs.
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horz(Map, X-Y, NextY, Cost) :-
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cost(Map, X-NextY, _),
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findall(
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Ci,
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( (Y < NextY -> between(Y, NextY, Yi); between(NextY, Y, Yi)),
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Yi =\= Y,
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cost(Map, X-Yi, Ci)),
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Costs),
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sum_list(Costs, Cost).
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% Cost = Costs.
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heur(X1-Y1, X2-Y2, Dist) :- Dist is sqrt((X1 - X2)**2 + (Y1 - Y2)**2).
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cost(Map, X-Y, Cost) :- nth0(X, Map, Row), nth0(Y, Row, Cost).
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print(Map) :- maplist([X]>>(atomic_list_concat(X, N), write(N), nl), Map).
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input(Name, Map) :- phrase_from_file(lines(Map), Name).
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lines([]) --> eos, !.
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lines([Nums|Lines]) -->
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line(Line), lines(Lines),
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{maplist([C, N]>>(N is C - 48), Line, Nums)}.
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line(Nums) --> digits(Nums), "\n".
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