day5.carp

; https://github.com/eriksvedang/advent_of_code_2017/blob/master/eriksvedang-carp/day5.carp
(use Int)
(use Array)
(use IO)

(defn answer [ints f]
  (let [pos 0
        len (count &ints)
        steps 0]
    (do
      (while (and (< -1 pos) (< pos len))
        (let [jump @(nth &ints pos)]
          (do
            (aset! &ints pos (f jump))                      ;; modify instruction
            (set! &pos (+ pos jump))                        ;; jump!
            (set! &steps (inc steps)))))
      steps)))

(defn part-2 [x]
  (if (< x 3)
    (+ x 1)
    (- x 1)))

(defn main []
  (let [input (read-file "../../resources/2017/day5")
        ints (copy-map from-string &(lines input))]
    (do
      (println (refstr (answer @&ints inc)))
      (println (refstr (answer @&ints part-2))))))

;$ carp
;> (load "day5.carp")
;> (build)
;> (run)