do 2017 day 7

2017/src/day07.clj

@@ -0,0 +1,67 @@
+(ns day07
+  (:require
+   [clojure.string :as str]
+   [core :refer [split-whitespace]]
+   [input-manager]))
+
+(def input
+  (->> (input-manager/get-input-raw 2017 7)
+       str/split-lines
+       (map (comp split-whitespace
+                  #(str/replace % #"," "")))))
+
+;; part 1
+(def base-node
+  (->> input
+       (filter (fn [[_ _ _ & children]] children))
+       (filter (fn [[node]]
+                 (empty? (filter (fn [[_ _ _ & children]]
+                                   (some #(= % node) children))
+                                 input))))
+       ffirst))
+
+(do
+  (def get-depth
+    (memoize (fn [node]
+               (let [[_ w-str _ & children] (first (filter (fn [[n]] (= node n))
+                                                           input))
+                     w (parse-long (subs w-str 1 (dec (count w-str))))]
+                 (apply + w (map get-depth children))))))
+  (def get-weight
+    (memoize (fn [node]
+               (let [w-str (->> input
+                                (filter (fn [[n]] (= node n)))
+                                first
+                                second)]
+                 (parse-long (subs w-str 1 (dec (count w-str))))))))
+  (def get-children
+    (memoize (fn [node] (->> input
+                             (filter (fn [[n]] (= node n)))
+                             first
+                             (drop 3))))))
+
+(defn get-children-data [node]
+  (map (juxt identity get-depth get-weight) (get-children node)))
+
+(defn get-counts [data]
+  (->> data
+         (map second)
+         frequencies
+         (sort-by second)))
+
+;; part 2
+(let [[bad-parent bad-node]
+      (loop [parent nil
+             node base-node]
+        (let [data (get-children-data node)
+              counts (get-counts data)
+              row (first (filter #(= (second %) (ffirst counts)) data))]
+          (if (= (count counts) 1)
+            [parent node]
+            (recur node (first row)))))
+      diff (->> bad-parent
+                get-children-data
+                get-counts
+                (map first)
+                (apply -))]
+  (- (get-weight bad-node) diff))