3 files changed, 77 insertions, 0 deletions
diff --git a/year2021/day6/consteval.cpp b/year2021/day6/consteval.cpp
new file mode 100644
index 0000000..f46da89
--- /dev/null
+++ b/year2021/day6/consteval.cpp
@@ -0,0 +1,32 @@
+#include <algorithm>
+#include <cstdint>
+#include <numeric>
+#include <iostream>
+
+consteval auto countFish(unsigned int day)
+{
+    unsigned char input[] = {
+        //3,4,3,1,2
+#include "in"
+    };
+
+    uint64_t counts[9];
+    std::fill(counts, counts + 9, 0);
+    for (int i = 0; i < sizeof(input); ++i)
+        ++counts[input[i]];
+
+    for (int i = 0; i < day; ++i) {
+        std::rotate(counts, counts + 1, counts + 9);
+        counts[6] += counts[8];
+    }
+
+    return std::accumulate(counts, counts + 9, 0ull);
+}
+
+int main()
+{
+    std::cout << "80: " << countFish(80) << std::endl;
+    std::cout << "256: " << countFish(256) << std::endl;
+    return 0;
+}
+
diff --git a/year2021/day6/part1.clj b/year2021/day6/part1.clj
new file mode 100644
index 0000000..70293f7
--- /dev/null
+++ b/year2021/day6/part1.clj
@@ -0,0 +1,20 @@
+(require '[clojure.string :as str])
+
+(def fish-init
+  (->> (read-line)
+       (#(str/split % #","))
+       (map #(Integer/parseInt %))
+       (vec)
+       )
+  )
+
+(defn cycle-day [fish]
+  (flatten
+    (for [f (map dec fish)]
+      (if (neg? f) [6 8] f)
+      )
+    )
+  )
+
+(println (count (nth (iterate cycle-day fish-init) 80)))
+
diff --git a/year2021/day6/part2.clj b/year2021/day6/part2.clj
new file mode 100644
index 0000000..ad6fe91
--- /dev/null
+++ b/year2021/day6/part2.clj
@@ -0,0 +1,25 @@
+(require '[clojure.string :as str])
+
+(->> (read-line)
+     (#(str/split % #","))
+     (map read-string)
+     (reduce #(update %1 %2 inc) (vec (repeat 9 0)))
+     (iterate
+       #(let [nf (conj (vec (rest %)) (first %))]
+          (update nf 6 (partial + (get nf 8)))
+          )
+       )
+     (#(nth % 256))
+     (apply +)
+     (println)
+     )
+
+; ->> read input from stdin
+;     split input string by commas
+;     convert string array into number array
+;     reduce to frequency counts
+;     create iterator that returns next day's counts
+;     get 256th iteration
+;     sum all frequency counts
+;     print results
+