52132 faxathisia (defun contains-duplicates-p (list) (/= (length list) (length (remove-duplicates list)))) (defparameter *graph* '((a d e) (b b c e f) (c) (d c f) (e a) (f b))) (defun next-paths (path) (mapcar #'(lambda (node) (append path (list node))) (cdr (assoc (car (last path)) *graph*)))) (defun next-paths-for-paths (paths) (mapcan #'next-paths paths)) (defun cyclep (path) (some #'(lambda (path) (equal (first path) (car (last path)))) (next-paths path))) (defun all-cycles () (loop for cycles := nil then (append cycles (remove-if-not #'cyclep paths)) for paths := (mapcar #'list (mapcar #'first *graph*)) then (remove-if #'contains-duplicates-p (next-paths-for-paths paths)) while paths finally (return cycles))) 3406102001 #lispcafe