Пребарување DFS - Коњски скок

(defun depth-first-search (start goal been-list moves)
  (cond ((equal start goal)
         (reverse (cons start been-list)))
        (t (try-moves start goal been-list moves moves))))

; Try-moves scans down the list of moves in moves-to-try,
; attempting to generate a child state.  If it produces
; this state, it calls depth-first-search to complete the search.

(defun try-moves (start goal been-list moves-to-try moves)
  (cond ((null moves-to-try) nil)
        ((member start been-list :test #'equal) nil)
        (t (let ((child (funcall (car moves-to-try) start)))
             (if child
               (or (depth-first-search (funcall (car moves-to-try) start)
                                       goal
                                       (cons start been-list)
                                       moves)
                   (try-moves start goal been-list (cdr moves-to-try) moves))
               (try-moves start goal been-list (cdr moves-to-try) moves))))))

; run-depth-first calls depth-first-search, initializing the been-list to ().
(defun run-depth (start goal moves)
  (depth-first-search start goal () moves)
)

(defun safe (state)
    (cond
        ((or(> (car state) 3)(>(cadr state) 3)(< (car state) 1)(< (cadr state) 1)) nil)
        (T state)
    )
)
(defun make-state (x y)
   (list x y)
)
(defun move1 (state)
 (safe (make-state (+ 2 (car state))(+ 1(cadr state))))
)
;x+2 y+1
(defun move2 (state)
(safe (make-state (+ 1 (car state))(+ 1 (cadr state))))
)
(defun move3(state)
(safe (make-state(- (car state) 2)(+ 1(cadr state))))
)
(defun move4 (state)
(safe (make-state(+ (car state) 1)(- (cadr state) 2)))
)
(defun move5(state)
(safe (make-state(+ (car state) 1)(- (cadr state) 2)))
)
;x+1 y+2
(print (run-depth'(1 1) '(3 3) '(move1 move2 move3 move4)))
;(run-depth '(1 1) '(3 3)  '(moves))