58 lines
1.5 KiB
Prolog
58 lines
1.5 KiB
Prolog
% ----------------------------------------------------------------------
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% The Computer Language Benchmarks Game
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% http://shootout.alioth.debian.org/
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% Contributed by Anthony Borla
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% Modified to run with YAP by Glendon Holst
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% ----------------------------------------------------------------------
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:- yap_flag(unknown,error).
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:- initialization(main).
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main :-
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transform_level(3),
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unix( argv([H|_]) ), number_atom(N,H),
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pidigits(N),
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statistics,
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statistics_jit.
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% ------------------------------- %
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pidigits(N) :- pidigits_(1, [1, 0, 0, 1], N, 0, 0).
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% ------------- %
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pidigits_(K, Z, N, Row, Col) :-
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(N > 0 ->
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next(Z, Y), safe(Z, Y, IsSafe),
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(IsSafe ->
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prod(Z, Y, RL), N1 is N - 1,
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(Col =:= 10 ->
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Cf is 1, Rf is 10 + Row, format('\t:~w\n~w', [Rf, Y])
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;
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Cf is 1 + Col, Rf is Row, format('~w', [Y])),
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!, pidigits_(K, RL, N1, Rf, Cf)
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;
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cons(Z, K, RL), K1 is K + 1,
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!, pidigits_(K1, RL, N, Row, Col))
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;
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NS is 10 - Col, tab(NS), RC is Row + Col, format('\t:~w\n', [RC])).
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% ------------- %
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next([Q, R, S, T], RV) :- RV is (3 * Q + R) // (3 * S + T).
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safe([Q, R, S, T], N, RV) :-
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V is ((4 * Q + R) // (4 * S + T)), (V =:= N -> RV = true ; RV = fail).
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comp([Q1, R1, S1, T1], [Q2, R2, S2, T2], [QO, RO, SO, TO]) :-
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QO is Q1 * Q2 + R1 * S2, RO is Q1 * R2 + R1 * T2,
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SO is S1 * Q2 + T1 * S2, TO is S1 * R2 + T1 * T2.
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prod(Z, N, RL) :- A2 is -10 * N, comp([10, A2, 0, 1], Z, RL).
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cons(Z, K, RL) :- A2 is 4 * K + 2, A4 is 2 * K + 1, comp(Z, [K, A2, 0, A4], RL).
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% ------------------------------- %
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