StackOverflowError

day_12.clj

(require '[clojure.string :as string])

(def pattern #"(\w+) (\w+) ?([\w-]+)?")

(def input
  (->> (slurp "day_12_input.txt")
       (string/split-lines)
       (map #(rest (re-find pattern %)))))

(def example
  (->> "cpy 41 a\ninc a\ninc a\ndec a\njnz a 2\ndec a\n"
       (string/split-lines)
       (map #(rest (re-find pattern %)))))

(defn get-value [key-or-value state]
  (if (contains? #{"a" "b" "c" "d"} key-or-value)
      (get state key-or-value)
      (Integer. key-or-value)))

(defn run-cpy [[_ p1 p2] state]
  (assoc state p2 (get-value p1 state)))

(defn run-jnz [todo done state]
  (let [[_ p1 p2] (first todo)
        value (get-value p1 state)
        offset (Integer. p2)]
    (cond
      (= 0 value) [(rest todo) (cons (first todo) done) state]
      (< 0 offset) [(drop offset todo) (concat (reverse (take offset todo)) done) state]
      (> 0 offset) [(concat (reverse (take (- 0 offset) done)) todo) (drop (- 0 offset) done) state])))

(defn run-inc [[_ p _] state]
  (update state p #(+ 1 %)))

(defn run-dec [[_ p _] state]
  (update state p #(- % 1)))

(defn run-commands [todo state]
  (loop [todo todo
         done []
         state state]
    (if (= 0 (count todo))
        state
        (case (first (first todo))
              "cpy"
              (recur (rest todo)
                     (cons (first todo) done)
                     (run-cpy (first todo) state))

              "jnz"
              (let [[new-todo new-done new-state] (run-jnz todo done state)]
                (recur new-todo new-done new-state))

              "inc"
              (recur (rest todo)
                     (cons (first todo) done)
                     (run-inc (first todo) state))

              "dec"
              (recur (rest todo)
                     (cons (first todo) done)
                     (run-dec (first todo) state))))))

(run-commands example {"a" 0, "b" 0, "c" 0, "d" 0})

(run-commands input {"a" 0, "b" 0, "c" 0, "d" 0})