17 lines
502 B
Prolog
17 lines
502 B
Prolog
:- op(700, xfx, l).
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:- op(700, xfx, r).
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From l To :- From to To-_.
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From r To :- From to _-To.
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answer(Answer) :- path([], aaa, Path), length(Path, Answer).
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path(_, zzz, []) :- !. % getting full path instead of just length for debugging
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path(Directions, From, [Move | Cdr]) :-
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next_step(Directions, Move, Remain),
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G =.. [Move, From, To], G,
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path(Remain, To, Cdr).
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next_step([Move | Remain], Move, Remain).
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next_step([], Move, Remain) :- direction(Str), atom_chars(Str, [Move | Remain]).
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