e5f4633c39
which included commits to RCS files with non-trunk default branches. git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@5 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
17 lines
303 B
Plaintext
17 lines
303 B
Plaintext
% n-queens with finite domains
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:- setval(domain,number).
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queen(N,L):-
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length(L,N),
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L::1..N,
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queen(L).
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queen([]).
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queen([X|Xs]):- safe(X,Xs,1),queen(Xs).
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safe(X,[],N).
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safe(X,[H|T],N):- no_attack(X,H,N), M is N+1, safe(X,T,M).
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no_attack(X,Y,N):- X ne Y, X ne Y-N, X ne Y+N, Y ne X-N, Y ne X+N.
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