Guided Practice 8.3

Modify 08-2-binary-search.rkt to design the following function:

;; binary-search-count : Nat (Nat -> Number) Number -> Nat
;; GIVEN: a number N, a function f : Nat -> Number and a number tgt
;; WHERE: f is monotonic (ie, i<=j implies f(i) <= f(j))
;; RETURNS: the number of i s.t. f(i) = x
;; EXAMPLES/TESTS:
(begin-for-test
  ;; successful search
  (check-equal?
    (binary-search-count 12 sqr 49)
    7)
  ;; unsuccessful search
  (check-equal?
    (binary-search-count 12 sqr 48)
    false)
  ;; make sure we don't miss the endpoints
  (check-equal?
    (binary-search-count 12 sqr 0)
    0)
  (check-equal?
    (binary-search-count 12 sqr 144)
    12))

Remember that your invariants are at least as important as your code.

[ANSWER]