66 lines
1.7 KiB
Prolog
66 lines
1.7 KiB
Prolog
:- use_module(library(simplex)).
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% tuples (name, weights, value).
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knapsack :-
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L = [( beef, 3.8, 36),
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( pork, 5.4, 43),
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( ham, 3.6, 90),
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( greaves, 2.4, 45),
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( flitch, 4.0, 30),
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( brawn, 2.5, 56),
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( welt, 3.7, 67),
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( salami, 3.0, 95),
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( sausage, 5.9, 98)],
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gen_state(S0),
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length(L, N),
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numlist(1, N, LN),
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( ( create_constraint_N(LN, L, S0, S1, [], LW, [], LV),
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constraint(LW =< 15.0, S1, S2),
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maximize(LV, S2, S3)
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)),
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compute_lenword(L, 0, Len),
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sformat(A1, '~~w~~t~~~w|', [Len]),
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sformat(A2, '~~t~~2f~~~w|', [10]),
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sformat(A3, '~~t~~2f~~~w|', [10]),
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print_results(S3, A1,A2,A3, L, LN, 0, 0).
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create_constraint_N([], [], S, S, LW, LW, LV, LV).
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create_constraint_N([HN|TN], [(_, W, V) | TL], S1, SF, LW, LWF, LV, LVF) :-
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constraint([x(HN)] >= 0, S1, S2),
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constraint([x(HN)] =< W, S2, S3),
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X is V/W,
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create_constraint_N(TN, TL, S3, SF, [x(HN) | LW], LWF, [X * x(HN) | LV], LVF).
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%
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compute_lenword([], N, N).
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compute_lenword([(Name, _, _)|T], N, NF):-
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atom_length(Name, L),
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( L > N -> N1 = L; N1 = N),
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compute_lenword(T, N1, NF).
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%
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print_results(_S, A1, A2, A3, [], [], WM, VM) :-
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sformat(W1, A1, [' ']),
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sformat(W2, A2, [WM]),
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sformat(W3, A3, [VM]),
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format('~w~w~w~n', [W1,W2,W3]).
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print_results(S, A1, A2, A3, [(Name, W, V)|T], [N|TN], W1, V1) :-
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variable_value(S, x(N), X),
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( X = 0 -> W1 = W2, V1 = V2
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;
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sformat(S1, A1, [Name]),
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sformat(S2, A2, [X]),
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Vtemp is X * V/W,
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sformat(S3, A3, [Vtemp]),
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format('~w~w~w~n', [S1,S2,S3]),
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W2 is W1 + X,
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V2 is V1 + Vtemp ),
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print_results(S, A1, A2, A3, T, TN, W2, V2).
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