22 lines
558 B
Text
22 lines
558 B
Text
:- object(list).
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:- public(permutation/2).
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permutation(List, Permutation) :-
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same_length(List, Permutation),
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permutation2(List, Permutation).
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permutation2([], []).
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permutation2(List, [Head| Tail]) :-
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select(Head, List, Remaining),
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permutation2(Remaining, Tail).
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same_length([], []).
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same_length([_| Tail1], [_| Tail2]) :-
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same_length(Tail1, Tail2).
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select(Head, [Head| Tail], Tail).
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select(Head, [Head2| Tail], [Head2| Tail2]) :-
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select(Head, Tail, Tail2).
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:- end_object.
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