Overengineered Day4, part two

executable/Main.hs

@@ -31,3 +31,5 @@ main = do
   let demoInput4 = "2-4,6-8\n2-3,4-5\n5-7,7-9\n2-8,3-7\n6-6,4-6\n2-6,4-8"
   putStrLn $ show $ Day4.solveA demoInput4
   putStrLn $ show $ Day4.solveA input4
+  putStrLn $ show $ Day4.solveB demoInput4
+  putStrLn $ show $ Day4.solveB input4

src/AoC/Day4.hs

@@ -3,9 +3,9 @@
 module AoC.Day4 where
 
 import Data.Text (Text)
--- import qualified Data.Text as T
 
 import Data.Attoparsec.Text
+import Data.Bits (xor)
 
 type Lower = Int
 type Higher = Int
@@ -36,3 +36,16 @@ solveA :: Text -> Either String Int
 solveA txt = do
   lines' <- parseInput txt
   pure $ (length . filter (uncurry eitherIncluded)) lines'
+
+--------------------------------------------------------------------------------
+-- Part 2
+overlap :: Range1D -> Range1D -> Bool
+overlap (Range1D l1 r1) (Range1D l2 r2) = (r1 >= l2) && (l1 <= r2)
+
+eitherOverlap :: Range1D -> Range1D -> Bool
+eitherOverlap range1 range2 = range1 `overlap` range2
+
+solveB :: Text -> Either String Int
+solveB txt = do
+  lines' <- parseInput txt
+  pure $ (length . filter (uncurry eitherOverlap)) lines'