gistfile1.txt

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Daniel D.             ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define mertwig
  (lambda (mine his)
    (define first-n
      (lambda (ilist n)
        (cond [(or (null? ilist) (zero? n)) '()]
          [else (cons (first ilist) (first-n (rest ilist) (sub1 n)))] )))
    (define howmany
      (lambda (ilist iatom)
        (cond [(null? ilist) 0]
          [else (+ (cond
                     [( equal? (first ilist) iatom) 1]
                     [else 0])
                   (howmany (rest ilist) iatom))] )))
    (define agran?
      (lambda (vec)
        (let ((x (arhelp vec)))
          (or (eq? x -2) (eq? x -1) (eq? x 0) (eq? x 1) (eq? x 2)))))
    (define arhelp
      (lambda (vec)
        (cond
          [(null? vec) 0]
          [else (cond
                  [(eq? (first vec) 'c) (add1 (arhelp (rest vec)))]
                  [else (sub1 (arhelp (rest vec)))])])))
    (define abs
      (lambda (num)
        (cond [(>= num 0) num]
          [else (- 0 num)] )))
    (define playing-titfortat?
      (lambda (mine his)
        (cond
          [(and
             ( > (length his) 10)
             ( equal? (first-n his (sub1 (length his)))  (rest mine))) #t]
          [else #f])))
    (define 6-check-c?
      (lambda (his)
        (cond
          [(equal? '(c c c c c c) (first-n his 6)) #t]
          [else #f] )))
    (define unresponsive?
      (lambda (mine his)
        (cond
          [(and (equal? '(c c c c) (first-n his 4))
                (member? 'd (first-n mine 5))) #t]
          [else #f] )))
    (define collision?
      (lambda (mine his)
        (cond
          [(and
             (or (equal? '(c d c d) (first-n mine 4))
                 (equal? '(d c d c) (first-n mine 4)))
             (or (equal? '(c d c d) (first-n his 4))
                 (equal? '(d c d c) (first-n his 4))))
           #t]
          [else #f] )))
    (define defection-rules?
      (lambda (his)
        (cond
          [( or (null? his) (null? (rest his))) #f]
          [(zero? (random 25)) #f]
          [(zero? (random 40)) #t]
          [(< 2 (howmany (first-n his 5) 'd)) #t]
          [else #f] )))
    (cond
      [(null? his)                    'c]
      [(defection-rules? his)         'd]
      [(playing-titfortat? mine his)  'c]
      [(and (> (length his) 10)
            (agran? (first-n his 10)))