1 665c255d 2023-08-04 jrmu (defun louis-queens (board-size)
 2 665c255d 2023-08-04 jrmu   (louis-queen-cols board-size board-size))
 3 665c255d 2023-08-04 jrmu 
 4 665c255d 2023-08-04 jrmu (defun louis-queen-cols (k board-size)
 5 665c255d 2023-08-04 jrmu   (if (= k 0)
 6 665c255d 2023-08-04 jrmu       (list empty-board)
 7 665c255d 2023-08-04 jrmu       (filter (lambda (positions) (safe k positions))
 8 665c255d 2023-08-04 jrmu 	      (flatmap
 9 665c255d 2023-08-04 jrmu 	       (lambda (new-row)
10 665c255d 2023-08-04 jrmu 		 (mapcar
11 665c255d 2023-08-04 jrmu 		  (lambda (rest-of-queens)
12 665c255d 2023-08-04 jrmu 		    (adjoin-position new-row k rest-of-queens))
13 665c255d 2023-08-04 jrmu 		  (louis-queen-cols (1- k) board-size)))
14 665c255d 2023-08-04 jrmu 	       (enumerate-interval 1 board-size)))))