day4

Makefile

@@ -1,4 +1,4 @@
-DAY = 3
+DAY = 4
 
 DIR = day$(DAY)
 

day4/main.hs

@@ -0,0 +1,31 @@
+import System.IO
+
+import Data.List.Split
+
+
+parseGrp :: String -> [(Int, Int)]
+parseGrp = map ((\ [s,e] -> (read s :: Int,read e :: Int)) . splitOn "-") . splitOn ","
+
+
+contained :: [(Int, Int)] -> Bool
+contained [(s1,e1),(s2,e2)]
+    | s1 <= s2 && e1 >= e2 = True
+    | s1 >= s2 && e1 <= e2 = True
+    | otherwise = False
+
+
+overlapping :: [(Int, Int)] -> Bool
+overlapping [(s1,e1),(s2,e2)]
+    | e1 < s2 = False
+    | s1 > e2 = False
+    | otherwise = True
+
+
+handler :: String -> String
+handler s = (show $ length $ filter contained groups) ++ "\n" ++
+            (show $ length $ filter overlapping groups) ++ "\n"
+    where groups = map parseGrp $ lines s
+
+main :: IO ()
+main = do
+    interact handler