linear-recursion-iteration.scm

; LINEAR RECURSION
(define (factorial n)
  (if (= n 1) 
      1 
      (* n (factorial (- n 1)))))
      
(factorial 3)
;(* 3 (factorial 2))
;(* 3 (* 2 (factorial 1)))
;(* 3 (* 2 1))
;(* 3 2)
;6

; LINEAR ITERATION
(define (factorial n) 
  (fact-iter 1 1 n))

(define (fact-iter product counter max-count)
  (if (> counter max-count)
      product
      (fact-iter (* counter product)
                 (+ counter 1)
                 max-count)))
                 
(factorial 3)
;(fact-iter 1 1 3)
;(fact-iter 1 2 3)
;(fact-iter 2 3 3)
;(fact-iter 6 4 3)
;6