Определить функцию для подсчёта количества вершин бинарного дерева

(defun tree-count-if (pred tree)
  (let ((count 0))
    (labels ((%count (ent)
               (cond ((listp ent)
                      (mapcar #'%count ent))
                     ((funcall pred ent)
                      (incf count)))))
      (%count tree)
      count)))
 
(defun in-range (x y)
  #'(lambda (z)
      (<= (min x y) z (max x y))))

CL-USER> (tree-count-if (in-range 1 3) '((2 (5 (nil 3 1) 7))))
3
CL-USER>

(defun tree-counter (tree vmin vmax)
  (let ((c 0))
    (dolist (i (flatten tree) c)
      (when (and (>= i vmin) (<= i vmax)) (setq c (+ c 1))))))
 
 
==> tree-counter
 
(tree-counter '((2 (5 (nil 3 1) 7))) 1 3)
 
==> 3

(defun flatten (lst) 
  (cond ((null lst) nil)
        ((null (car lst)) (flatten (cdr lst)))  
        ((atom (car lst)) (cons (car lst) (flatten (cdr lst))))
        (t (append (flatten (car lst)) (flatten (cdr lst))))))

CL-USER 3 : 2 > (defun flatten (lst) 
  (cond ((null lst) nil)
        ((null (car lst)) (flatten (cdr lst)))  
        ((atom (car lst)) (cons (car lst) (flatten (cdr lst))))
        (t (append (flatten (car lst)) (flatten (cdr lst))))))
FLATTEN
 
CL-USER 4 : 2 > (defun tree-counter (tree vmin vmax)
  (let ((c 0))
    (dolist (i (flatten tree) c)
      (when (and (>= i vmin) (<= i vmax)) (setq c (+ c 1))))))
TREE-COUNTER
 
CL-USER 5 : 2 > (tree-counter '((2 (5 (nil 3 1) 7))) 1 3) 
 
3 ;; верно!

(defun counter (x z w &aux (a (car w)) (d (cdr w)))
  (cond ((null w) 0)
        ((listp a) (+ (counter x z a) (counter x z d)))
        ((and a (<= x a z)) (1+ (counter x z d)))
        ((counter x z d))))
 
> (counter 1 3 '((2 (5 (nil 3 1) 7))))
3

(defun flat (w &optional acc) 
  (cond ((null w) acc)
        ((atom w) (cons w acc))
        ((flat (car w) (flat (cdr w) acc)))))
 
(defun counter (x z w)
  (loop for a in (flat w) counting (<= x a z)))
 
> (counter 1 3 '((2 (5 (nil 3 1) 7))))
3

(defun flat (w &optional acc) 
  (cond ((null w) acc)
        ((atom w) (cons w acc))
        ((flat (car w) (flat (cdr w) acc)))))
 
(defun counter (x z w)
  (count-if #'(lambda (a) (<= x a z)) (flat w)))
 
> (counter 1 3 '((2 (5 (nil 3 1) 7))))
3

(defun flat (w)
  (loop for a in w 
        if (and a (atom a)) collect a
        else nconc (flat a)))
    
(defun counter (x z w)
  (count-if #'(lambda (a) (<= x a z)) (flat w)))
 
> (counter 1 3 '((2 (5 (nil 3 1) 7))))
3

(defun flat (w)
  (loop for a in w 
        if (and a (atom a)) collect a
        else nconc (flat a)))
 
(defun counter (x z w)
  (loop for a in (flat w) counting (<= x a z)))
 
> (counter 1 3 '((2 (5 (nil 3 1) 7))))
3

(defun tree-count (tree a b)
  (if (null tree) 0
      (let ((l (tree-count (cadr tree) a b))
            (r (tree-count (caddr tree) a b)))
           (if (and (>= (car tree) a) (<= (car tree) b)) (+ (car tree) l r) (+ l r)))))
 
==> tree-count
 
(tree-count '(1 (6 nil nil) (8 (12 nil nil) (-7 nil nil))) 1 5)
 
==> 1
 
(tree-count '(1 (6 nil nil) (8 (12 nil nil) (-7 nil nil))) 1 10)
 
==> 15
 
(tree-count '(1 (6 nil nil) (8 (12 nil nil) (-7 nil nil))) -10 10)
 
==> 8