Re-add first solution from temporary aoc repo

hs/src/Aoc/Y2019/A01.hs

@@ -0,0 +1,19 @@
+module Aoc.Y2019.A01
+  ( solve201901
+  ) where
+
+fuel :: Integer -> Integer
+fuel n = (n `div` 3) - 2
+
+iteratedFuel :: Integer -> Integer
+iteratedFuel = sum . takeWhile (> 0) . tail . iterate fuel
+
+solve201901 :: FilePath -> IO ()
+solve201901 f = do
+  values <- (map read . lines) <$> readFile f
+
+  putStr "Total fuel: "
+  print $ sum $ map fuel values
+
+  putStr "Total fuel (iterated): "
+  print $ sum $ map iteratedFuel values