JOI 2009 予選 2.scm

(use file.util)
(use srfi-1)

(letrec ((input (file->string-list "input.txt"))
         (n-m (map string->number (string-split (car input) #\Space)))
         (n (car n-m))
         (m (cdr n-m))
         (dat (map string->number (cdr input)))
         (mass (take dat n))
         (dise (drop dat n)))
  (let loop((index 1) (count 1))
    (let ((i (+ index (list-ref dise (- count 1)))))
      (if (>= i n)
          (display count)
          (let ((i (+ i (list-ref mass (- i 1)))))
            (if (>= i n)
                (display count)
                (loop i (+ count 1))))))))