N Queen

CommonLispでN Queenを解く。きっと正しいと信じたい。

(defun check-nqueen (n lst)
  (not
   (or
    (find n lst)
    (loop
       :named hoge
       :for i from (1+ n)
       :for j downfrom (1- n)
       :for rest = lst then (cdr rest)
       :for m = (car rest) then (car rest)
       :finally (return-from hoge nil)
       :while m
       :do (when (or (= m i) (= m j))
      (return-from hoge t))))))
(defun nqueen (n)
  (let ((result nil))
    (labels
 ((inner (i lst r)
    (when (check-nqueen i lst)
      (if (= r 1)
   (push (cons i lst) result)
   (loop
      :with next = (cons i lst)
      :for i from 1 to n
      :do (inner i next (1- r)))))))
      (loop
  :for i from 1 to n
  :do (inner i nil n)))
    result))