From 81c974b56755f008f0bae33cbb2450492c4c5931 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Wed, 9 Dec 2020 18:10:55 +0000
Subject: [PATCH] Shorten 2020_09

---
 hs/src/Aoc/Y2020/D09.hs | 34 +++++++++-------------------------
 1 file changed, 9 insertions(+), 25 deletions(-)

diff --git a/hs/src/Aoc/Y2020/D09.hs b/hs/src/Aoc/Y2020/D09.hs
index f9e9e9c..21d64dc 100644
--- a/hs/src/Aoc/Y2020/D09.hs
+++ b/hs/src/Aoc/Y2020/D09.hs
@@ -1,16 +1,10 @@
-module Aoc.Y2020.D09
-  ( day
-  ) where
-
-import           Data.List
+module Aoc.Y2020.D09 (day) where
 
 import           Aoc.Day
 import           Aoc.Parse
+import           Data.List
 
-parser :: Parser [Int]
-parser = manyLines decimal
-
-splitAndGroup :: Int -> [Int] -> [([Int], Int)]
+splitAndGroup :: Int -> [a] -> [([a], a)]
 splitAndGroup width xs = case splitAt width xs of
   (_, [])   -> []
   (as, b:_) -> (as, b) : splitAndGroup width (drop 1 xs)
@@ -18,22 +12,12 @@ splitAndGroup width xs = case splitAt width xs of
 isValid :: [Int] -> Int -> Bool
 isValid nums n = elem n $ (+) <$> nums <*> nums
 
-continuousSubsequences :: [a] -> [[a]]
-continuousSubsequences = filter (not . null) . concatMap tails . inits
-
 findRanges :: Int -> [Int] -> [[Int]]
-findRanges target = filter ((== target) . sum) . continuousSubsequences
-
-solver :: [Int] -> IO ()
-solver nums = do
-  putStrLn ">> Part 1"
-  let (_, invalidN) = head $ dropWhile (uncurry isValid) $ splitAndGroup 25 nums
-  print invalidN
-
-  putStrLn ""
-  putStrLn ">> Part 2"
-  let weakness = head $ findRanges invalidN nums
-  print $ minimum weakness + maximum weakness
+findRanges target = filter ((== target) . sum) . concatMap tails . inits
 
 day :: Day
-day = dayParse parser solver
+day = dayParse (manyLines decimal) $ \nums -> do
+  let (_, invalidN) = head $ dropWhile (uncurry isValid) $ splitAndGroup 25 nums
+  putStrLn $ ">> Part 1: " ++ show invalidN
+  let weakness = head $ findRanges invalidN nums
+  putStrLn $ ">> Part 2: " ++ show (minimum weakness + maximum weakness)