https://gist.github.com/wasao/5006686 これ見てclで書こうと思ったら波に乗れなかった感。 cf http://d.hatena.ne.jp/ayato0211/20130221/1361438221 http://d.hatena.ne.jp/torazuka/20130221/ddd

baroque.lisp

(defstruct node
  (rireki nil :type list)
  (state '(3 2 1 2) :type (and list (not null))))

(defun inner-solve (slist)
  (if 
   (issolved (car slist))
   (printrireki (car slist))
   (inner-solve (nconc (cdr slist) (nextnodesforall (car slist) '(0 1 2 3))))))

(defun issolved (node)
  (equal (node-state node) '(2 3 0 1)))

(defun printrireki (node)
  (print (node-rireki node)))
  
(defun nextnodesforall (node list)
  (iter (for a in list)
        (collect 
            (make-node 
             :rireki (append (node-rireki node) (list a))
             :state (nextstate (node-state node) a)))))

(defun nth1- (list n)
  (if (= n 0)
      (cons (1- (car list)) (cdr list))
      (cons (car list) (nth1- (cdr list) (1- n)))))

(defun nextstate (state move)
  (mapcar #'(lambda (x) (mod x 4)) (nth1- (mapcar #'1+ state) (mod (1+ move) 4))))

(defun solve (state)
  (inner-solve (list (make-node :state state))))