87 lines
2.5 KiB
Mathematica
87 lines
2.5 KiB
Mathematica
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:- module day13.
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:- interface.
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:- import_module basics.
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:- pred run(part::in, lines::in, answer::out) is cc_multi.
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:- implementation.
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:- import_module int.
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:- import_module string.
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:- import_module list.
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:- type packet ---> i(int); l(list(packet)).
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:- type packets == {packet, packet}.
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:- pred packets(list(packets)::out, lines::in) is nondet.
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packets(Ps, Lines) :- packets(Ps, to_char_list(join_list("", Lines)), []).
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:- pred packets(list(packets)::out, chars::in, chars::out) is multi.
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packets([{P, Q} | Rest]) --> packet(P), packet(Q), packets(Rest).
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packets([]) --> [].
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:- pred packet(packet::out, chars::in, chars::out) is nondet.
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:- import_module day4.
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packet(i(I)) --> day4.number(I).
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packet(l(Ps)) --> ['['], inner(Ps), [']'].
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:- pred inner(list(packet)::out, chars::in, chars::out) is multi.
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inner(Ps) --> inner1(Ps).
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inner([]) --> [].
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:- pred inner1(list(packet)::out, chars::in, chars::out) is nondet.
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inner1([P | Ps]) --> packet(P), (if [','] then inner1(Ps) else {Ps = []}).
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:- pred cmps(list(packet)::in, list(packet)::in, comparison_result::out) is det.
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cmps([], [], =).
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cmps([], [_|_], <).
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cmps([_|_], [], >).
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cmps([P|Ps], [Q|Qs], C) :-
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cmp(P, Q, C1), (if C1 = (=) then cmps(Ps, Qs, C) else C = C1).
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:- pred cmp(packet::in, packet::in, comparison_result::out) is det.
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cmp(i(I), i(J), C) :- compare(C, I, J).
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cmp(l(Ps), l(Qs), C) :- cmps(Ps, Qs, C).
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cmp(i(I), l(Qs), C) :- cmps([i(I)], Qs, C).
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cmp(l(Ps), i(J), C) :- cmps(Ps, [i(J)], C).
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:- func cmp(packet, packet) = comparison_result.
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cmp(P, Q) = C :- cmp(P, Q, C).
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:- pred ok(packets::in) is semidet.
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ok({P, Q}) :- not cmp(P, Q, >).
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div1 = l([l([i(2)])]).
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div2 = l([l([i(6)])]).
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:- pred divider(packet::in) is semidet.
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divider(div1). divider(div2).
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:- mode unary == (pred(in) is semidet).
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:- pred indices(pred(T)::unary, int::in, list(T)::in, list(int)::out) is det.
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indices(_, _, [], []).
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indices(P, I, [X|Xs], Is) :-
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indices(P, I + 1, Xs, Is0),
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(if P(X) then Is = [I|Is0] else Is = Is0).
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:- pred indices(pred(T)::unary, list(T)::in, list(int)::out) is det.
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indices(P, Xs, Is) :- indices(P, 1, Xs, Is).
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:- func merge(list(packets)) = list(packet).
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merge(Ps) = foldl(func({X, Y}, Zs) = [X,Y|Zs], Ps, []).
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:- pragma no_determinism_warning(run/3).
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run(one, Lines, int(sum(Is))) :-
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if packets(Ps, Lines) then
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indices(ok, Ps, Is)
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else
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die("bad input").
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run(two, Lines, int(prod(Is))) :-
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if packets(Pairs, Lines) then
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indices(divider, sort(cmp, [div1, div2 | merge(Pairs)]), Is)
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else
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die("bad input").
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