ドドスコ問題

ddsk.rkt

#lang racket
(define ds (vector "ドド" "スコ"))

(define (take-upto lst pos)
 (cond
   [(<= pos 0) null]
   [(null? lst) null]
   [else (cons (car lst)
               (take-upto (cdr lst) (sub1 pos)))]))
   
(define (take-history history)
  (take-upto history 12))

(define (ddsk-rec history)
  (if (equal? (take-history history)
              (list 1 1 1 0 1 1 1 0 1 1 1 0))
    (displayln "ラブ注入♡")
    (let ([i (random 2)])
      (display (vector-ref ds i))
      (ddsk-rec (cons i history)))))

(ddsk-rec null)