day20: learn futures, arrays

diff --git a/day20/partboth.clj b/day20/partboth.clj
index 4e460ca8639f3e444281442c8e77594f9129d4ba..33a4d4fc033596879d47453d188214525b7f49ee 100644 (file)
--- a/day20/partboth.clj
+++ b/day20/partboth.clj
@@ -1,44 +1,43 @@
 (require '[clojure.string :as str])
 
 (defn pad-input-map [in-map pad-val]
-  (let [pad-row (repeat (+ 4 (count (first in-map))) pad-val)
-        pad-side (repeat 2 pad-val)]
-    (mapv vec
-      (concat
-        [pad-row pad-row]
-        (mapv #(concat pad-side % pad-side) in-map)
-        [pad-row pad-row]))))
+  (let [ly (count in-map) lx (count (first in-map))
+        sy (+ 4 ly) sx (+ 4 lx)
+        buffer (byte-array (repeat (* sy sx) pad-val))]
+    (doseq [y (range 0 ly) x (range 0 lx)]
+      (aset-byte buffer (+ (* sx (+ 2 y)) 2 x) (get-in in-map [y x])))
+    (mapv vec (partition sx buffer))))
 
 (defn get-number [in-map y x]
-  (concat (subvec (get in-map (dec y)) (dec x) (+ 2 x))
-          (subvec (get in-map y) (dec x) (+ 2 x))
-          (subvec (get in-map (inc y)) (dec x) (+ 2 x))))
+  (map (partial get-in in-map)
+       [[(dec y) (dec x)] [(dec y) x] [(dec y) (inc x)]
+        [y (dec x)]       [y x]       [y (inc x)]
+        [(inc y) (dec x)] [(inc y) x] [(inc y) (inc x)]]))
 
 (defn get-new-pixel [enhance-algo in-map y x]
   (->> (get-number in-map y x)
-       str/join
-       (#(Integer/parseInt % 2))
-       (get enhance-algo)
-       {\. 0 \# 1}))
+       (reduce #(cond-> (* 2 %1) (= 1 %2) inc) 0)
+       (get enhance-algo)))
 
 (defn build-output-number-map [enhance-algo in-map]
-  (let [pad-val (if (= \# (first enhance-algo)) (first (first in-map)) 0)
+  (let [pad-val (if (pos? (first enhance-algo)) (first (first in-map)) 0)
         padded-in-map (pad-input-map in-map pad-val)]
-    (for [y (range 1 (dec (count padded-in-map)))]
-      (for [x (range 1 (dec (count (first padded-in-map))))]
-        (get-new-pixel enhance-algo padded-in-map y x)
-        ))))
+    (->> (for [y (range 1 (dec (count padded-in-map)))]
+           (future
+             (mapv (partial get-new-pixel enhance-algo padded-in-map y)
+                   (range 1 (dec (count (first padded-in-map)))))))
+         (mapv deref))))
 
-(defn count-lit-pixels [in-map]
-  ((frequencies (flatten in-map)) 1))
+(defn count-lit-pixels [in-map] ((frequencies (flatten in-map)) 1))
 
 (let [[enhance-algo in-map]
       (->> (slurp "./in")
            str/split-lines
-           ((juxt
-           first
-           (comp (partial mapv #(mapv {\. 0 \# 1} %))
-                 (partial drop 2)))))
+           ((juxt (comp (partial mapv {\. 0 \# 1}) first)
+                  (comp (partial mapv #(mapv {\. 0 \# 1} %)) (partial drop 2)))))
       image-output (iterate (partial build-output-number-map enhance-algo) in-map)]
-  (println (count-lit-pixels (nth image-output 50))))
+  (println "Part 1:" (count-lit-pixels (nth image-output 2)))
+  (println "Part 2:" (count-lit-pixels (nth image-output 50))))
+
+(shutdown-agents)