day4

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

day4.hs

@@ -0,0 +1,29 @@
+import Lib (split)
+
+main :: IO ()
+main = do
+  input <- readFile "day4.in"
+  putStr "Q1: "
+  print $ q1 input
+  putStr "Q2: "
+  print $ q2 input
+
+q1 :: String -> Int
+q1 =
+  length
+    . filter
+      ( \x ->
+          let [[a, b], [c, d]] = map (map (read :: String -> Int) . split '-') $ split ',' x
+           in a >= c && b <= d || c >= a && d <= b
+      )
+    . lines
+
+q2 :: String -> Int
+q2 =
+  length
+    . filter
+      ( \x ->
+          let [[a, b], [c, d]] = map (map (read :: String -> Int) . split '-') $ split ',' x
+           in b >= c && a <= d || d >= a && c <= b
+      )
+    . lines