copy-queue that returns a copy of a queue.1.Draw three different trees that would print as ((A) (A) (A)). Write an expression that generates each.
(cons (cons 'a nil) (cons (cons 'a nil) (cons (cons 'a nil) nil)))
(make-array '(3 1) :initial-element 'a)
(vector '(a) '(a) '(a))
2.Assuming make-queue, enqueue, and dequeue are defined as in Figure 12.7, draw the queue in box-notation after each step:
(defun make--queue () (cons nil nil))
(defun enqueue (obj q)
(if (null (car q))
(setf (cdr q) (setf (car q) (list obj)))
(setf (cdr (cdr q)) (list obj)
(cdr q) (cdr (cdr q))))
(car q))
(defun dequeue (q)
(pop (car q)))
;;> (setf q (make-queue)) ==> (NIL)
+---+---+
|nil|nil|
+---+---+
;;> (enqueue 'a q) ==> (A)
+---+---+
| | |
+-+-+-+-+
| +-+
| |
+-+-+---+
| a |nil|
+---+---+
;;> (enqueue 'b q) ==> (A B)
+---+---+
| | |
+-+-+-+-+
| |
| +---------+
+-+-+----+ +---+---+
| a | +--+ b |nil|
+---+----+ +---+---+
;;> (dequeue q) ==> A
+---+
| a |
+---+
copy-queue that returns a copy of a queue.(defun copy-queue (q)
(if (null (car q))
nil
(list (cons (car (car q))
(copy-queue (list (cdr (car q)) (cdr q))))
(cdr q))))
4.Define a function that takes an object and a queue, and puts the object on the front of the queue.
(defun push-queue (obj q)
(setf (car q) (push obj (car q))))
5.Define a function that takes an object and a queue, and (destructively) moves the first (eql) instance of the object to the front of the queue.
(defun push-first-queue (obj q)
(push-queue obj q))
6.Define a function that takes an object and a possibly cdr-circular list, and returns true if the object is a member of the list.
(defun cdr-circle-m (obj cc)
(if (cdr-circle-p cc)
(member obj cc)
nil))
7.Define a function that returns true when its argument is a cdr-circular list.
(defun cdr-circle-p (c)
(and
(consp c)
(eql (cdr c) c)))
8.Define a function that returns true when its argument is a car-circular list.
(defun car-circle-p (cc)
(and
(consp cc)
(eql (car cc) cc)))