ドラクエVIIのバロックタワーのパズルを解く ( http://d.hatena.ne.jp/torazuka/20130221/ddd ) を参考に問いてみたけど、出力結果が思うようにいかない…。

baroque.scm

(define (baroque input)
  (define (ok? ls)
    (let ((model-1 (list-ref ls 0))
	  (model-2 (list-ref ls 1))
	  (model-3 (list-ref ls 2))
	  (model-4 (list-ref ls 3)))
      (and (= model-1 2)
	   (= model-2 3)
	   (= model-3 0)
	   (= model-4 1))))

  (define (next x)
    (let ((next-x (+ x 1)))
      (if (= next-x 4)
	  0
	  next-x)))

  (define (push n ls)
    (let loop ((m (next n))
	       (count 0)
	       (ls ls)
	       (out '()))
      (cond
       ((null? ls) (reverse out))
       ((= count m)
	(loop m
	      (+ count 1)
	      (cdr ls)
	      (cons (car ls) out)))
       (else
	(loop m
	      (+ count 1)
	      (cdr ls)
	      (cons (next (car ls)) out))))))

  (let loop ((count 0)
	     (max 8)
	     (input input)
	     (output '()))
    (cond
     ((> count max) '())
     ((ok? input)
      (reverse output))
     (else
      (list (loop (+ count 1)
		  max
		  (push 0 input)
		  (cons 0 output))
	    (loop (+ count 1)
		  max
		  (push 1 input)
		  (cons 1 output))
	    (loop (+ count 1)
		  max
		  (push 2 input)
		  (cons 2 output))
	    (loop (+ count 1)
		  max
		  (push 3 input)
		  (cons 3 output)))))))

(baroque '(3 2 2 3))

;; ex.
;; input  '(3 2 2 3)
;; output '(0 0 0 1 1 2 2 3)