62 lines
1.5 KiB
Mathematica
62 lines
1.5 KiB
Mathematica
:- module day3.
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:- interface.
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:- import_module basics.
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:- import_module list.
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:- import_module univ.
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:- pred run(part::in, list(string)::in, univ::out) is cc_multi.
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:- implementation.
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:- import_module int.
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:- import_module char.
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:- import_module string.
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:- pred split(chars::in, chars::out, chars::out) is semidet.
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split(X, L, H) :-
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Len = length(X), even(Len),
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split_list(Len / 2, X, L, H).
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:- pred common(list(chars)::in, char::out) is nondet.
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common([S | Ss], C) :- member(C, S), (Ss = [] ; common(Ss, C)).
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:- func prio(char) = int.
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prio(C) = I :-
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if is_lower(C) then
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I = to_int(C) - to_int('a') + 1
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else
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I = to_int(C) - to_int('A') + 27.
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:- type triple(T) ---> t(T, T, T).
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:- pred threes(list(T)::in, list(triple(T))::out) is semidet.
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threes([], []).
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threes([X, Y, Z | Rest], [t(X, Y, Z) | Groups]) :- threes(Rest, Groups).
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:- pred go1(string::in, int::out) is cc_multi.
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go1(Line, Out) :-
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if split(to_char_list(Line), Fst, Snd),
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common([Fst, Snd], C)
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then
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Out = prio(C)
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else
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die("invalid line: ""%s""", [s(Line)]).
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:- pred go2(triple(string)::in, int::out) is cc_multi.
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go2(t(X, Y, Z), Prio) :-
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if common(map(to_char_list, [X, Y, Z]), C) then
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Prio = prio(C)
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else
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die("no item in common in:\n - %s\n - %s\n - %s",
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[s(X), s(Y), s(Z)]).
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run(one, Lines, univ(sum(Prios))) :-
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map(go1, Lines, Prios).
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run(two, Lines, univ(sum(Prios))) :-
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if threes(Lines, Groups) then
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map(go2, Groups, Prios)
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else
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die("not a multiple of three lines").
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