[이승중]

(define tr1 (node (leaf 'a)
(node (leaf' b)
(node (leaf 'c)
(leaf 'd)))))

(define tr2 (node (leaf 'a) (node (node (leaf 'b) (leaf 'x)) (leaf 'y))))

(traverse tr1)
(traverse tr2)

(define q1 (make-emptyQ-1list))
(define q2 (pushQ-1list 'orange q1))
(define q3 (pushQ-1list 'apple q2))
(car (popQ-1list q3)) ;orange

(is-1list? (cons '1list 'a)) ; #f
(is-1list? q1) ; #t

(define q4 (cdr (popQ-1list q3)))
(car (popQ-1list q4)) ;apple

(define q5 (cdr (popQ-1list q4)))
(car (popQ-1list q5)) ; 빈큐입니다. 에러



(define q21 (make-emptyQ-2list))
(define q22 (pushQ-2list 'orange q21))
(define q23 (pushQ-2list 'apple q22))
(car (popQ-2list q23)) ;orange

(is-2list? (cons '2lst (cons 'a 'a))) ; #f
(is-2list? q21) ; #t
(is-2list? q1) ; #f

(define q24 (cdr (popQ-2list q23)))
(car (popQ-2list q24)) ;apple

(define q25 (cdr (popQ-2list q24)))
(car (popQ-2list q25)) ; 빈큐입니다. 에러


(is-1list? (make-emptyQ 'one)) ;#t
(is-1list? (make-emptyQ 'two)) ;#f
(is-2list? (make-emptyQ 'one)) ;#f
(is-2list? (make-emptyQ 'two)) ;#t

(define q1 (make-emptyQ 'one))
(is-emptyQ? q1) ; #t

(define q2 (pushQ '(1 2 3) q1))
(define q3 (pushQ 45 q2))
(define q4 (pushQ 'hi q3))

(define e1_q5 (popQ q4))
(define e2_q6 (popQ (cdr e1_q5)))
(define e3_q7 (popQ (cdr e2_q6)))

(car e1_q5) ; '(1 2 3)
(car e2_q6) ; 45
(car e3_q7) ; 'hi

(ZipperNQ (pushQ '() (pushQ '(1 2 3) (pushQ '(4 5) (make-emptyQ 'two)))))

[강동현]

답이 어떻게 되나요?