more day09 golfing

p2 is just reverse p1 lol
2023-12-09 18:41:37 +01:00 · 2023-12-09 18:41:37 +01:00 · 0e134abdaa
parent c970abf345
commit 0e134abdaa
1 changed files with 4 additions and 7 deletions
--- a/2023/day09/day09.hs
+++ b/2023/day09/day09.hs
@ -3,15 +3,12 @@ import Control.Arrow
 main :: IO ()
 main = do
  input <- parse <$> readFile "input"
-  print $ day09 input
+  print $ (day09 &&& day09 . map reverse) input

 parse :: String -> [[Int]]
 parse = map (map read . words) . lines

-day09 :: [[Int]] -> (Int, Int)
+day09 :: [[Int]] -> Int
 day09 =
-  (sum *** sum) .
-  unzip .
-  map
-    ((sum . map last &&& foldr1 (-) . map head) .
-     takeWhile (not . null) . iterate (zipWith (-) =<< tail))
+  sum .
+  map (sum . map last . takeWhile (not . null) . iterate (zipWith (-) =<< tail))