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pl:prolog:pllib:8_queens_2 [2019/06/27 15:50] (aktualna) |
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| + | ====== 8 queens 2 ====== | ||
| + | {{tag>puzzle chess}} | ||
| + | ===== Description ===== | ||
| + | Program solves 8 queens problem | ||
| + | |||
| + | **Source**: PrologTutorial (on-line tutorial) | ||
| + | ===== Download ===== | ||
| + | Program source code: {{prolog:pllib:8_queens_2.pl}} | ||
| + | ===== Listing ===== | ||
| + | <code prolog> | ||
| + | /* prolog tutorial 2.11 Chess queens challenge puzzle */ | ||
| + | |||
| + | perm([X|Y],Z) :- perm(Y,W), takeout(X,Z,W). | ||
| + | perm([],[]). | ||
| + | |||
| + | takeout(X,[X|R],R). | ||
| + | takeout(X,[F|R],[F|S]) :- takeout(X,R,S). | ||
| + | |||
| + | solve(P) :- | ||
| + | perm([1,2,3,4,5,6,7,8],P), | ||
| + | combine([1,2,3,4,5,6,7,8],P,S,D), | ||
| + | all_diff(S), | ||
| + | all_diff(D). | ||
| + | |||
| + | combine([X1|X],[Y1|Y],[S1|S],[D1|D]) :- | ||
| + | S1 is X1 +Y1, | ||
| + | D1 is X1 - Y1, | ||
| + | combine(X,Y,S,D). | ||
| + | combine([],[],[],[]). | ||
| + | |||
| + | all_diff([X|Y]) :- \+member(X,Y), all_diff(Y). | ||
| + | all_diff([X]). | ||
| + | |||
| + | |||
| + | /* ?- solve(P). | ||
| + | P = [5,2,6,1,7,4,8,3] ; | ||
| + | P = [6,3,5,7,1,4,2,8] ; | ||
| + | ... | ||
| + | |||
| + | ?- setof(P,solve(P),Set), length(Set,L). | ||
| + | ... | ||
| + | L = 92 | ||
| + | */ | ||
| + | </code> | ||
| + | ===== Comments ===== | ||
