route(a,d,1).
route(a,h,1).
route(a,b,1).
route(b,e,1).
route(b,c,1).
route(c,f,1).
route(c,e,1).
route(f,i,1).
route(f,h,1).
route(e,d,1).
route(d,g,1).
route(g,j,1).
route(g,l,1).
route(h,k,1).
route(i,k,1).
route(i,l,1).
route(j,m,1).
route(j,o,1).
route(k,n,1).
route(l,m,1).
route(l,o,1).
route(m,n,1).
route(n,o,1).

ha_path(A, B) :-route(A, B, _), !.
ha_path(A, B) :-route(A, X, _), ha_path(X, B).

%--------------------------------------------------------

crossing(A, B,Visited,[B|Visited]) :-route(A, B,_).
crossing(A, B, Visited, Cam) :-route(A, C, _),
                             C == B,
                             + member(C, Visited),
                             crossing(C, B, [C|Visited], Cam).

%------------------------------------------------

%Find the ways and the cost between two nodes.

path(A, B, Cam) :- crossing(A, B, [A], Cam).
paths(A, B, Lc) :-setof(Cam, path(A, B, Cam), Lc), !.
paths(_,_,[]).

costPath(A, B, Cam, Cost) :-crossingCost(A, B, [A], Cam, Cost).
crossingCost(A, B, Visited,[B|Visited],Cost1) :-route(A, B, Cost1).
crossingCost(A, B, Visited, Cam, Cost) :-route(A, C, Cost2)
                                       ,C == B,+ member(C, Visited)
                     ,crossingCost(C, B, [C|Visited], Cam, CostResto)
                     ,Cost is Cost2 + CostResto.

%----------------------------------------------------
%Find the paths and cost between two points.

costPaths(A, B, Lc) :-
setof(Cam/Cost,costPath(A,B,Cam,Cost), Lc), !.
costPaths(_,_,[]).

%---------------------------------------------------