;;; ==========================
;;;  CMPU-145, Spring 2013
;;;  asmt6-helper.txt
;;; ==========================
;;;  Loads asmt5-helper.txt and then defines some functions needed
;;;  for asmt6.

(load "asmt5-helper.txt")

;;;  TESTER-SHOW-LIST
;;; -----------------------------------------
;;;  INPUT:  An expression that evaluates to a list
;;;  OUTPUT:  Prints out that expression verbatim, and
;;;    then uses a helper function to display the contents
;;;    of the list to which that expression evaluates.
;;;  Example:  (tester-show-list '(cons 1 (cons 2 ())))
;;;            (define *my-listy* '(1 2 3 4))
;;;            (tester-show-list '*my-listy*)

(define tester-show-list
  (lambda (quoted-listy)
    (printf "~A ==>~%" quoted-listy)
    (tester-show-list-helper (eval quoted-listy))))

;;;  TESTER-SHOW-LIST-HELPER
;;; -----------------------------------
;;;  Prints contents of input list on separate lines.

(define tester-show-list-helper
  (lambda (listy)
    (cond
      ((null? listy) 
       (newline))
      (#t
       (printf "~A~%" (first listy))
       (tester-show-list-helper (rest listy))))))

;;;  *PB-59*  -- The set of numbers from which the first five numbers on
;;;              a powerball ticket are drawn

(define *pb-59* '(1 2 3 4 5 6 7 8 9 10
                    11 12 13 14 15 16 17 18 19 20
                    21 22 23 24 25 26 27 28 29 30
                    31 32 33 34 35 36 37 38 39 40
                    41 42 43 44 45 46 47 48 49 50
                    51 52 53 54 55 56 57 58 59))

;;;  *PB-35*  --  The set of numbers from which a powerball is chosen

(define *pb-35* '(1 2 3 4 5 6 7 8 9 10
                    11 12 13 14 15 16 17 18 19 20
                    21 22 23 24 25 26 27 28 29 30
                    31 32 33 34 35))


;;;  GEN-RAND-PB-TICKET
;;; ---------------------------------------
;;;  INPUTS:  None
;;;  OUTPUT:  A list of six numbers:  the first five are chosen
;;;   from (1,2,3,...,59) (no replacement); the last one is chosen
;;;   from (1,2,3,...,35)

(define gen-rand-pb-ticket
  (lambda ()
    ;; Note how we CONS the powerball onto the FRONT of the list,
    ;; and then REVERSE it to place the powerball at the end!!
    (reverse (cons ;; Pick the powerball (from 1 to 35)
                   (+ 1 (random 35))
                   ;; Pick the five numbers from 1 to 59
                   (rand-choose-k 5 *pb-59*)))))

;;;  NUM-MATCHES
;;; ---------------------------------
;;;  INPUTS:  LISTY, LISTZ, two lists
;;;  OUTPUT:  The number of elements of LISTY that also appear in LISTZ
;;;   (same as the number of elements in the intersection of the two lists)

(define num-matches
  (lambda (listy listz)
    (cond
      ;; Base Case:  LISTY is empty
      ((null? listy)
       ;; So no matches
       0)
      ;; Recursive Case 1:  We found a match!
      ((member (first listy) listz)
       ;; So add 1 to the recursive function call on the rest of LISTY
       (+ 1 (num-matches (rest listy) listz)))
      ;; Recursive Case 2:  We did not find a match!
      (#t
       ;; So just focus on the REST of listy
       (num-matches (rest listy) listz)))))

(define *draw-ticket* '(1 2 3 4 5 20))