https://benchmarksgame-team.pages.debian.net/benchmarksgame/description/binarytrees.html#binarytrees

binarytrees.scm

(define node cons)                                                                                                    
(define node-left car)
(define node-right cdr)

(define (make d)
  (if (= d 0)
      (node #f #f)
      (let ([d2 (1- d)])
        (node (make d2) (make d2)))))

(define (check t)
  (if (node-left t)
      (+ 1 (check (node-left t)) (check (node-right t)))
      1))

(define (main n)
  (define min-depth 4)
  (define max-depth (max (+ min-depth 2) n))
  (define stretch-depth (1+ max-depth))
  (format #t "stretch tree of depth ~a\t check: ~a\n" stretch-depth (check (make stretch-depth)))
  (let ([long-lived-tree (make max-depth)])
    (do ([d 4 (+ d 2)]) ([not (< d (1+ max-depth))])
      (let ([iterations (ash 1 (+ (- max-depth d) min-depth))])
        (format #t "~a\t trees of depth ~a\t check: ~a\n"
                iterations
                d
                (let sum ([i iterations] [n 0])
                  (if (zero? i)
                      n
                      (sum (1- i) (+ n (check (make d)))))))))
    (format #t "long lived tree of depth ~a\t check: ~a\n"
            max-depth
            (check long-lived-tree))))

(main (string->number (list-ref (command-line) 1)))