; Returns number of moves to solve k-disc puzzle
(define (hanoi k)
  (if (= k 1)
      1
      (+ (* 2 (hanoi (- k 1))) 1)))

; Returns the auxillary pole given source a and
; destination b
(define (auxillary a b)
  (let ((s (+ a b)))
    (cond ((= s 1) 2)
          ((= s 3) 0)
          ((= s 2) 1))))

; Prints moves required to solve k-disc puzzle
; k = number of discs
; a = source pole (0, 1, or 2)
; b = destination pole (0, 1, or 2, not equal to source pole)
(define (hanoi2 k a b)
  (if (= k 1)
      (printf "Pole ~a to pole ~a\n" a b)
      (begin
        (hanoi2 (- k 1) a (auxillary a b))
        (printf "Pole ~a to pole ~a\n" a b)
        (hanoi2 (- k 1) (auxillary a b) b))))