graphCost(a, 63).
graphCost(b, 26).
graphCost(c, 60).
graphCost(f, 32).

edge(a,b).
edge(a,c).
edge(b,d).
edge(c,d).
edge(d,e).
edge(b,b).
edge(c,f).

cost(a, 1).
cost(b, 2).
cost(c, 4).
cost(d, 8).
cost(e, 16).
cost(f, 32).

visitAndMove2(A) :-
  +edge(A, _),
  nb_getval('Visited', Visited),
  ( +member(A, Visited) ->
    nb_setval('Visited', [A | Visited]),
    cost(A, C),
    nb_getval('Cost', Cost),
    TC is Cost + C,
    nb_setval('Cost', TC),
    write(' --> '), write(A), write(': '), writeln([A | Visited])
  ;
    write(A), writeln(' --|')).

visitAndMove2(A) :-
  edge(A, Child),
  A == Child,
  nb_getval('Visited', Visited),
  +member(Child, Visited),
  nb_setval('Visited', [Child | Visited]),
  cost(Child, C),
  nb_getval('Cost', Cost),
  TC is Cost + C,
  nb_setval('Cost', TC),
  write(A), write(' --> '), write(Child), write(': '), writeln([Child | Visited]),
  visitAndMove2(Child).

graphCost(A, Cost) :-
  nb_setval('Visited', [A]),
  cost(A, C),
  nb_setval('Cost', C),
  visitAndMove2(A),
  nb_getval('Cost', Cost).