do day 13

2017/src/day13.clj

@@ -0,0 +1,58 @@
+(ns day13
+  (:require
+   [clojure.string :as str]
+   [core]
+   [input-manager]))
+
+(def lengths (->> (input-manager/get-input 2017 13)
+                  (map (comp #(mapv parse-long %)
+                             #(str/split % #": ")))
+                  (into {})))
+
+(defn move-sensor [{:keys [idx depth increasing-depth] :as sensor}]
+  (let [[keep-moving reverse-step] (if increasing-depth [inc dec] [dec inc])
+        depth' (keep-moving depth)]
+    (if (or (> depth' (dec (lengths idx)))
+            (< depth' 0))
+      (-> sensor
+          (update :depth reverse-step)
+          (update :increasing-depth not))
+      (assoc sensor :depth depth'))))
+
+(def initial-sensors (->> lengths
+                          keys
+                          (map #(hash-map :depth 0
+                                          :idx %
+                                          :increasing-depth true))))
+
+(defn is-spotted-by-sensors [acc pos]
+  (some #(when (and (= (:idx %) pos)
+                    (= (:depth %) 0))
+           %)
+        (:sensors acc)))
+
+(->> lengths keys (apply max) inc range
+     (reduce (fn [acc pos]
+               (let [spotted (is-spotted-by-sensors acc pos)]
+                 (-> acc
+                     (update :sensors (partial map move-sensor))
+                     (update :solution + (if spotted
+                                           (* pos (lengths pos))
+                                           0)))))
+             {:sensors initial-sensors
+              :solution 0})
+     :solution)
+
+(loop [i 0
+       start-val initial-sensors]
+  (if
+   (= true
+      (->> lengths keys (apply max) inc range
+           (reduce (fn [acc pos]
+                     (let [spotted (is-spotted-by-sensors acc pos)]
+                       (if spotted
+                         (reduced true)
+                         (update acc :sensors (partial map move-sensor)))))
+                   {:sensors start-val})))
+    (recur (inc i) (map move-sensor start-val))
+    i))