1 files changed, 36 insertions, 0 deletions
diff --git a/year2021/day3/part2.clj b/year2021/day3/part2.clj
new file mode 100644
index 0000000..00e656f
--- /dev/null
+++ b/year2021/day3/part2.clj
@@ -0,0 +1,36 @@
+(require '[clojure.string :as str])
+
+(def bitcount 12)
+(def input
+  (->> "./in"
+      (slurp)
+      (str/split-lines)
+      (map #(Integer/parseInt % 2))
+      )
+  )
+
+(defn countbit [lst bit]
+  (->> lst
+       (map #(if (bit-test % bit) 1 0))
+       (apply +)
+       )
+  )
+
+(defn filterbit [lst bit v]
+  (if (= 1 (count lst))
+    lst
+    (filter #(= (bit-test % bit) v) lst)
+    )
+  )
+
+(loop [bit (dec bitcount) lst0 input lst1 input]
+  (if (and (= 1 (count lst0)) (= 1 (count lst1)))
+    (println (map * lst0 lst1))
+    (recur
+      (dec bit)
+      (filterbit lst0 bit (>= (countbit lst0 bit) (/ (count lst0) 2)))
+      (filterbit lst1 bit (< (countbit lst1 bit) (/ (count lst1) 2)))
+      )
+    )
+  )
+