sicp exercise 1.21

; Exercise 1.21. Use the smallest-divisor procedure to find the smallest divisor of each of the
; following numbers: 199, 1999, 19999.


(define (smallest-divisor n)
    (define (square number) (* number number))
    (define (divides? n divisor) (= (remainder n divisor) 0))
    (define (find-divisor n divisor)
        (cond ((> (square divisor) n) n)
              ((divides? n divisor) divisor)
              (else (find-divisor n (+ divisor 1)))))
    (find-divisor n 2))


(display (smallest-divisor 10)) (newline)
(display (smallest-divisor 199)) (newline)
(display (smallest-divisor 1999)) (newline)
(display (smallest-divisor 19999)) (newline)