(define (gcd-nodiv m n)
  (cond [(= n m) n]
        [(or (= m 1) (= n 1)) 1]
        [(> m n) (gcd-nodiv n (- m n))]
        [else    (gcd-nodiv m (- n m))]))

;;
;; 以下は測定用
;;
;;ループ回数のカウント
(define (gcd-nodiv/cnt m n cnt)
  (cond [(= n m) (values n cnt)]
        [(or (= m 1) (= n 1)) (values 1 cnt)]
        [(> m n) (gcd-nodiv/cnt n (- m n) (+ cnt 1))]
        [else    (gcd-nodiv/cnt m (- n m) (+ cnt 1))]))

;;メモワイズ版fib
(define fib
  (let1 memo (make-hash-table 'eqv?)
    (lambda (n)
      (cond [(<= n 2) 1]
            [(hash-table-get memo n #f)]
            [else (let1 val (+ (fib (- n 1)) (fib (- n 2)))
                    (hash-table-put! memo n val)
                    val)]))))