;;;10進数を２進数にしてそのnotをとって
;;;最後に10進数に戻す
;;;
;;; Scheme
(define foo
  (lambda (n)
    (2to10 (notbin (10to2 n)))))

(define 2to10
  (lambda (lat)
    (cond
     ((null? lat) 0)
     ((= (car lat) 1)
      (+ (expt 2 (1- (length lat)))
         (2to10 (cdr lat))))
     (else
      (2to10 (cdr lat))))))

(define notbin
  (lambda (lst)
    (cond
     ((null? lst) '())
     ((= (car lst) 0)
      (cons 1 (notbin (cdr lst))))
     (else
      (cons 0 (notbin (cdr lst)))))))
  
(define 10to2
  (lambda (n)
    (cond
     ((zero? n) '())
     (else
      (orbin (cons 1 (fill 0 (log2 n)))
             (10to2 (- n
                       (expt 2 (log2 n)))))))))

(define orbin
  (lambda (lat1 lat2)
     (reverse (orbin-sub (reverse lat1)
                        (reverse lat2)))))

(define orbin-sub
  (lambda (lat1 lat2)
    (cond
     ((null? lat1) lat2)
     ((null? lat2) lat1)
     ((or (= 1 (car lat1))
          (= 1 (car lat2)))
      (cons 1 (orbin-sub (cdr lat1)
                         (cdr lat2))))
     (else
      (cons 0 (orbin-sub (cdr lat1)
                         (cdr lat2)))))))

(define fill
  (lambda (a n)
    (cond
     ((zero? n) '())
     (else
      (cons a (fill a (1- n)))))))

(define log2
  (lambda (a)
    (cond
     ((< a 2) 0)
     (else
      (1+ (log2 (div a 2)))))))

(define div
  (lambda (a b)
    (cond
     ((< a b) 0)
     (else
      (1+ (div (- a b) b))))))