36 lines
1.3 KiB
Perl
36 lines
1.3 KiB
Perl
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:- op(700, xfx, before).
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:- table galaxy/2.
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:- table no_galaxy_row/2.
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:- table no_galaxy_col/2.
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:- use_module(library(pio)).
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:- initialization(start, main).
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start :-
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input('input.txt', Map),
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findall(Dist, (galaxy(Map, A), galaxy(Map, B), A before B,
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distance(Map, A, B, Dist)),
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Dists),
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sum_list(Dists, Answer),
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writef('Answer=%w\n', [Answer]).
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distance(Map, X1-Y1, X2-Y2, Dist) :-
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findall(X, no_galaxy_row(Map, X), EmptyXs),
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findall(Y, no_galaxy_col(Map, Y), EmptyYs),
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include(between(X1, X2), EmptyXs, ExpandedX), length(ExpandedX, RowsToAdd),
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include(between(Y1, Y2), EmptyYs, ExpandedY), length(ExpandedY, ColsToAdd),
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Dist is abs(X1 - X2) + abs(Y1 - Y2) + RowsToAdd + ColsToAdd.
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between(End1, End2, N) :- End1 < N, N < End2; End1 > N, N > End2.
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no_galaxy_row(Map, X) :- nth0(X, Map, Row), maplist([46]>>(true), Row).
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no_galaxy_col(Map, Y) :- maplist({Y}/[Row]>>(nth0(Y, Row, 46)), Map).
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galaxy(Map, X-Y) :- nth0(X, Map, Row), nth0(Y, Row, 35).
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before(X1-Y1, X2-Y2) :- X1 < X2; X1 =:= X2, Y1 < Y2.
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input(FileName, Map) :- phrase_from_file(lines(Map), FileName).
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lines([]) --> eos, !.
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lines([Line|Lines]) --> line(Line), lines(Lines).
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eos([], []).
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line([]) --> ( "\n" ; eos ), !.
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line([L|Ls]) --> [L], line(Ls).
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