35 lines
700 B
Prolog
35 lines
700 B
Prolog
read_file(Stream, []) :-
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at_end_of_stream(Stream).
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read_file(Stream, [(Cmd, N)|L]) :-
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\+ at_end_of_stream(Stream),
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read_line_to_codes(Stream, C),
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string_chars(S, C),
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split_string(S, " ", "", [S0, S1]),
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atom_string(Cmd, S0),
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number_string(N, S1),
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read_file(Stream, L).
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main :-
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open('../input/02', read, Stream),
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read_file(Stream, Lines), !,
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close(Stream),
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step(Lines, X, Y),
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Z is X * Y,
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print((X, Y, Z)).
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step([], 0, 0).
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step([(forward, N)|Tail], X, Y) :-
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step(Tail, X0, Y),
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X is X0 + N.
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step([(up, N)|Tail], X, Y) :-
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step(Tail, X, Y0),
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Y is Y0 - N.
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step([(down, N)|Tail], X, Y) :-
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step(Tail, X, Y0),
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Y is Y0 + N.
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