35 lines
1.1 KiB
OpenEdge ABL
35 lines
1.1 KiB
OpenEdge ABL
/*Jacob Besse
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Prolog*/
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/*This is the data set.*/
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edge(a,b,2). edge(a,c,3). edge(a,d,1).
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edge(b,d,2). edge(b,e,2). edge(b,f,4).
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edge(c,a,3). edge(c,d,2). edge(c,e,2).
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edge(d,a,1). edge(d,b,2).
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edge(e,c,2). edge(e,d,2). edge(e,f,1).
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edge(f,b,4). edge(f,c,3). edge(f,e,1).
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len([], 0).
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len([_|T], N):- len(T, X), N is X+1 .
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best_path(Visited, Total):- path(a, a, Visited, Total).
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path(Start, Fin, Visited, Total) :- path(Start, Fin, [Start], Visited, 0, Total).
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path(Start, Fin, CurrentLoc, Visited, Costn, Total) :-
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edge(Start, StopLoc, Distance), NewCostn is Costn + Distance, \+ member(StopLoc, CurrentLoc),
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path(StopLoc, Fin, [StopLoc|CurrentLoc], Visited, NewCostn, Total).
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path(Start, Fin, CurrentLoc, Visited, Costn, Total) :-
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edge(Start, Fin, Distance), reverse([Fin|CurrentLoc], Visited), len(Visited, Q),
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(Q\=7 -> Total is 100000; Total is Costn + Distance).
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shortest_path(Path):-setof(Cost-Path, best_path(Path,Cost), Holder),pick(Holder,Path).
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best(Cost-Holder,Bcost-_,Cost-Holder):- Cost<Bcost,!.
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best(_,X,X).
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pick([Cost-Holder|R],X):- pick(R,Bcost-Bholder),best(Cost-Holder,Bcost-Bholder,X),!.
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pick([X],X).
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