Racket - 在某些约束下创建地板功能

Question

I'm quite stuck on trying to create a floor function with the following constraints:

I'm only allowed to use the following functions in section 1.5 of this page: http://docs.racket-lang.org/htdp-langs/beginner.html .

However you're not allowed to use the floor, round, ceiling and sgn function. In addition to all this, you are unable to use recursion, cond, lists or even helper functions.

Note: use only beginner student documentation

Answer 1

Here is a hint to get you started:

floor(x) = 0            if 0 <=x < 1
floor(x) = 1+floor(x-1) if x>1

In Scheme notation:

(define (myfloor x)
  (cond
    [(below-one? x)  0]
    [else           (add-one (myfloor (subtract-one x)))]))

All you need to do, is to figure out how to write below-one and subtract-one .