day4

2022/day04/day04.hs

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+import Data.List.Split
+import Data.List
+
+main :: IO ()
+main = do
+  input <- parse <$> readFile "input"
+  print $ day4a input
+  print $ day4b input
+
+parse :: String -> [[[Int]]]
+parse = map (map ((\[x,y]->[read x .. read y]) . splitOn "-") . splitOn ",") . lines
+
+testEnclave :: [[Int]] -> Bool
+testEnclave (x:y:[]) = a == x || a == y
+    where a = x `intersect` y
+
+day4a :: [[[Int]]] -> Int
+day4a = sum . map (fromEnum . testEnclave)
+
+day4b :: [[[Int]]] -> Int
+day4b = sum . map (fromEnum . not . null . foldl1 intersect)

2022/day04/testinput

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+2-4,6-8
+2-3,4-5
+5-7,7-9
+2-8,3-7
+6-6,4-6
+2-6,4-8