do day 3

2017/src/day03.clj

@@ -0,0 +1,51 @@
+(ns day03
+  (:require input-manager))
+
+(def input (parse-long (input-manager/get-input-raw 2017 3)))
+
+(def directions [:right :up :left :down])
+(def to-the-left {:right :up
+                  :up :left
+                  :down :right
+                  :left :down})
+(def cardinal-dir-offsets {:right [1 0]
+                           :left [-1 0]
+                           :down [0 -1]
+                           :up [0 1]})
+
+(def all-offsets #{[1 0] [-1 0] [0 -1] [0 1] [1 1] [-1 -1] [1 -1] [-1 1]})
+
+(->> (loop [loc [1 0]
+            i 2
+            grid {[0 0] 1}
+            [dir :as dirs] (cycle directions)]
+       (if (< i input)
+         (let [left-loc (mapv + loc (cardinal-dir-offsets (to-the-left dir)))
+               grid' (assoc grid loc i)
+               i' (inc i)]
+           (if (contains? grid left-loc)
+             (recur (mapv + loc (cardinal-dir-offsets dir)) i' grid' dirs)
+             (recur left-loc i' grid' (rest dirs))))
+         loc))
+     (map abs)
+     (apply +))
+
+(->> (loop [loc [1 0]
+            grid {[0 0] 1}
+            [dir :as dirs] (cycle directions)]
+       (let [left-loc (mapv + loc (cardinal-dir-offsets (to-the-left dir)))
+             value (->> all-offsets
+                        (map (comp
+                              #(or (grid %) 0)
+                              #(mapv + % loc)))
+                        (reduce +))
+             grid' (assoc grid loc value)]
+         (cond
+           (> value input)
+           value
+
+           (contains? grid left-loc)
+           (recur (mapv + loc (cardinal-dir-offsets dir)) grid' dirs)
+
+           :else
+           (recur left-loc grid' (rest dirs))))))