day 5.2 prolog (tentative)

pl/05.2.pl

@@ -0,0 +1,188 @@
+parse_line(S, [A, B, C, D]) :-
+    split_string(S, " ->", "", [X, _, _, _, Y]),
+    split_string(X, ",", "", [A0, B0]),
+    split_string(Y, ",", "", [C0, D0]),
+    number_string(A, A0),
+    number_string(B, B0),
+    number_string(C, C0),
+    number_string(D, D0).
+
+read_file(Stream, []) :-
+    at_end_of_stream(Stream).
+read_file(Stream, [X|L]) :-
+    \+ at_end_of_stream(Stream),
+    read_line_to_codes(Stream, C),
+    string_chars(S, C),
+    parse_line(S, X),
+    read_file(Stream, L).
+
+main :-
+    open('../input/05', read, Stream),
+    %open('05', read, Stream),
+    read_file(Stream, Lines), !,
+    close(Stream),
+    minmax_seq(Lines, X0, X1, Y0, Y1),
+    C = [X0 - 10, X1 + 10, Y0 - 10, Y1 + 10],
+    convert_coords(Lines, C, L1),
+    create_grid(C, G),
+    mark_lines(G, L1, G1),
+    count_ge2(G1, W),
+    print(W).
+
+convert_coords([], _, []).
+convert_coords([[A0,A1,A2,A3]|As], [X0, X1, Y0, Y1], [[B0,B1,B2,B3]|Bs]) :-
+    C0 is A0 - X0,
+    C1 is A1 - Y0,
+    C2 is A2 - X0,
+    C3 is A3 - Y0,
+    ((
+        (horizontal([C0, C1, C2, C3]); vertical([C0, C1, C2, C3])),
+        B0 is min(C0, C2),
+        B2 is max(C0, C2),
+        B1 is min(C1, C3),
+        B3 is max(C1, C3)
+    );
+    (
+        C0 =< C2,
+        B0 is C0,
+        B1 is C1,
+        B2 is C2,
+        B3 is C3
+    );
+    (
+        C2 < C0,
+        B0 is C2,
+        B1 is C3,
+        B2 is C0,
+        B3 is C1
+    )),
+    convert_coords(As, [X0, X1, Y0, Y1], Bs).
+
+create_row(0, []).
+create_row(X, [0|As]) :-
+    X > 0,
+    X1 is X - 1,
+    create_row(X1, As).
+create_grid([X0, X1, Y0, Y1], A) :-
+    create_grid(X1 - X0 + 1, Y1 - Y0 + 1, A).
+create_grid(_, 0, []).
+create_grid(X, Y, [A|As]) :-
+    Y > 0,
+    Y1 is Y - 1,
+    create_row(X, A),
+    create_grid(X, Y1, As).
+
+minmax([A, B, C, D], X0, X1, Y0, Y1) :-
+    X0 is min(A, C),
+    X1 is max(A, C),
+    Y0 is min(B, D),
+    Y1 is max(B, D).
+
+minmax_seq([A], X0, X1, Y0, Y1) :-
+    minmax(A, X0, X1, Y0, Y1).
+minmax_seq([A|As], X0, X1, Y0, Y1) :-
+    minmax_seq(As, X00, X01, Y00, Y01),
+    minmax(A, X10, X11, Y10, Y11),
+    X0 is min(X00, X10),
+    X1 is max(X01, X11),
+    Y0 is min(Y00, Y10),
+    Y1 is max(Y01, Y11).
+
+vertical([A, _, A, _]).
+horizontal([_, A, _, A]).
+diagonal_a([A, B, C, D]) :-
+    C - A = D - B.
+diagonal_b([A, B, C, D]) :-
+    C - A = B - D.
+
+applicable(A) :-
+    (vertical(A); horizontal(A)).
+
+prefix_n(0, _, []).
+prefix_n(X, [A|As], [A|Ps]) :-
+    X > 0,
+    X1 is X - 1,
+    prefix_n(X1, As, Ps).
+
+suffix_n(N, A, S) :-
+    reverse(A, B),
+    prefix_n(N, B, P),
+    reverse(P, S).
+
+add_one([], []).
+add_one([A|As], [B|Bs]) :-
+    B is A + 1,
+    add_one(As, Bs).
+
+mark_in_row(X, [A, B], Y) :-
+    length(X, L),
+    L1 is L - B - 1,
+    prefix_n(A, X, Pfx),
+    suffix_n(L1, X, Sfx),
+    append([Pfx, Q, Sfx], X),
+    add_one(Q, W),
+    append([Pfx, W, Sfx], Y).
+
+mark_row(X, [A, B, C, B], Y) :-
+    length(X, L),
+    L1 is L - B - 1,
+    prefix_n(B, X, Pfx),
+    suffix_n(L1, X, Sfx),
+    nth0(B, X, Row0),
+    mark_in_row(Row0, [A, C], Row1),
+    append([Pfx, [Row1], Sfx], Y).
+
+mark_cols([], _, []).
+mark_cols([X|Xs], A, [Y|Ys]) :-
+    mark_in_row(X, [A, A], Y),
+    mark_cols(Xs, A, Ys).
+mark_col(X, [A, B, A, D], Y) :-
+    length(X, L),
+    L1 is L - D - 1,
+    prefix_n(B, X, Pfx),
+    suffix_n(L1, X, Sfx),
+    append([Pfx, Q, Sfx], X),
+    mark_cols(Q, A, W),
+    append([Pfx, W, Sfx], Y).
+
+mark_diag_a(X, [A, A, A, A], Y) :-
+    mark_row(X, [A, A, A, A], Y).
+mark_diag_a(X, [A, B, C, D], Y) :-
+    A \= C,
+    diagonal_a([A, B, C, D]),
+    mark_diag_a(X, [A, B, A, B], Y0),
+    A1 is A + 1,
+    B1 is B + 1,
+    mark_diag_a(Y0, [A1, B1, C, D], Y).
+
+mark_diag_b(X, [A, A, A, A], Y) :-
+    mark_row(X, [A, A, A, A], Y).
+mark_diag_b(X, [A, B, C, D], Y) :-
+    A \= C,
+    diagonal_b([A, B, C, D]),
+    mark_diag_b(X, [A, B, A, B], Y0),
+    A1 is A + 1,
+    B1 is B - 1,
+    mark_diag_b(Y0, [A1, B1, C, D], Y).
+
+mark_line(X, Z, Y) :-
+    mark_col(X, Z, Y); mark_row(X, Z, Y); mark_diag_a(X, Z, Y); mark_diag_b(X, Z, Y), !.
+
+mark_lines(X, [], X).
+mark_lines(X, [Z|Zs], Y) :-
+    mark_line(X, Z, Y0), !,
+    mark_lines(Y0, Zs, Y).
+
+count_ge2_row([], 0).
+count_ge2_row([A|As], C) :-
+    A >= 2,
+    count_ge2_row(As, C1),
+    C is C1 + 1.
+count_ge2_row([A|As], C) :-
+    A < 2,
+    count_ge2_row(As, C).
+count_ge2([], 0).
+count_ge2([X|Xs], Y) :-
+    count_ge2(Xs, Y0),
+    count_ge2_row(X, Y1),
+    Y is Y0 + Y1.