67 lines
1.7 KiB
Mathematica
67 lines
1.7 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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:- pred run(part::in, list(string)::in, answer::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(string::in, string::out, string::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(X, Len / 2, L, H).
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:- pred member(char::out, string::in) is nondet.
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member(C, S) :-
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nondet_int_in_range(0, length(S) - 1, I),
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index(S, I, C).
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:- pred common(list(string)::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(In, Out) :- threes(Out, In, []).
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:- pred threes(list(triple(T))::out, list(T)::in, list(T)::out) is semidet.
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threes([]) --> =([]).
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threes([t(X, Y, Z) | Rest]) --> [X, Y, Z], threes(Rest).
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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(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([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", [s(X), s(Y), s(Z)]).
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run(one, Lines, int(sum(Prios))) :- map(go1, Lines, Prios).
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run(two, Lines, int(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("%d lines given (not a multiple of 3)", [i(length(Lines))]).
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