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(define x (cons (list 1 2) (list 3 4)))
(define (length x)
(cond ((null? x) 0)
((not (pair? x)) 1)
(else (+ (length (cdr x)) 1))))
(define (count-leaves x)
(cond ((null? x) 0)
((not (pair? x)) 1)
(else (+ (count-leaves (car x))
(count-leaves (cdr x))))))
(length x)
(count-leaves x)
;; Exercise 2.24
;; Length is wrong !!!
;; (car (cdr )) to get the left leaf
(define list-1 (list 1 (list 2 (list 3 4))))
(length list-1)
(count-leaves list-1)
;; Exercise 2.25
(car (cdr (car (cdr (cdr (list 1 3 (list 5 7) 9))))))
(car (car (list (list 7))))
(car (cdr (car (cdr (car (cdr (car (cdr (car (cdr (car (cdr (list 1 (list 2 (list 3 (list 4 (list 5 (list 6 7))))))))))))))))))
;; Exercise 2.26
(define x (list 1 2 3))
(define y (list 4 5 6))
(append x y)
(car (car (cons x y)))
(car (car (list x y)))
(car (cdr (cons x y)))
(car (car (cdr (list x y))))
;; Exercise 2.27
!!! ;; Exercise2.18
(define (reverse items)
(if (null? (cdr items))
items
(append (reverse (cdr items))
(cons (car items) nil))))
(define (deep-reverse items)
(if (null? (cdr items))
(if (not (pair? (car items)))
items
(cons (deep-reverse (car items)) nil))
(append (cond ((pair? (cdr items))
(deep-reverse (cdr items)))
((pair? (car (cdr items)))
(cons (deep-reverse (car (cdr items))) nil))
;; Some problem in else.
(else (deep-reverse (cdr items))))
(cond ((pair? (car items))
(cons (deep-reverse (car items)) nil))
(else (cons (car items) nil))))))
(define y
(list (list 1 2) (list 3 4) (list 5 6)))
(define z (list (list 1 2)))
(deep-reverse z)
(reverse z)
(reverse y)
(deep-reverse y)
(cons (deep-reverse (car (list (list 1 2)))) nil)
(deep-reverse
(list 1 (list 2 3) 4 (list 5 6)))
(define x
(list (list 1 2) (list 3 4)))
(list (list 1 2) (list 3 4))
(reverse x)
(deep-reverse x)
(deep-reverse (list 3 4))
(deep-reverse (list 1 2 3))
(reverse (list 1 2 3))
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