day 9

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

day09.hs

@@ -0,0 +1,22 @@
+import Data.Either (rights)
+import Data.Map qualified as M
+import Data.Text qualified as T
+import Data.Text.Read qualified as TR
+import Lib (readFile', tRead)
+import Text.Parsec
+
+main :: IO ()
+main = do
+  input <- map (map tRead . T.words) . T.lines <$> readFile' "day09.in"
+  
+  putStr "Q1: "
+  print . sum $ map (sum . map last . extrap) input
+  
+  putStr "Q2: "
+  print . sum $ map (sum . map last . extrap . reverse) input
+
+extrap :: [Int] -> [[Int]]
+extrap xs = take (length xs) $ iterate first' xs
+  where
+    first' :: [Int] -> [Int]
+    first' xs = zipWith (-) (tail xs) xs