Day 22, Part 1

src/Day22.hs

@@ -0,0 +1,17 @@
+module Day22 (day22_1) where
+
+import Data.Bits
+
+getSecretNumber :: Integer -> Int -> Integer
+getSecretNumber x 0 = x
+getSecretNumber x n =
+  let x' = ((x `shiftL` 6) `xor` x) `mod` 16777216
+      x'' = ((x' `shiftR` 5) `xor` x') `mod` 16777216
+   in getSecretNumber (((x'' `shiftL` 11) `xor` x'') `mod` 16777216) (n - 1)
+
+day22_1 :: IO ()
+day22_1 = do
+  contents <- map read . lines <$> readFile "input/day22.txt"
+  putStrLn $
+    "Day 22, Puzzle 1 solution: "
+      ++ show (sum $ map (`getSecretNumber` 2000) contents)