1 files changed, 47 insertions, 0 deletions
diff --git a/day02/day02.hs b/day02/day02.hs
new file mode 100644
index 0000000..b263574
--- /dev/null
+++ b/day02/day02.hs
@@ -0,0 +1,47 @@
+import Data.List
+import Data.List.Split
+import Data.Maybe
+
+data Dir = Up | Down
+
+safe :: [Int] -> Int -> Dir -> Bool
+safe [] _ _ =
+  True
+safe (x:xs) last Up
+  | x - last < 1 = False
+  | x - last > 3 = False
+  | otherwise = safe xs x Up
+safe (x:xs) last Down
+  | last - x < 1 = False
+  | last - x > 3 = False
+  | otherwise = safe xs x Down
+
+isSafe (x:y:rest)
+  | y > x = safe (y:rest) x Up
+  | x > y = safe (y:rest) x Down
+  | otherwise = False
+
+deleteAt x list =
+  let (h, t) = splitAt x list in
+    h ++ (drop 1 t)
+
+isSafeDamped Nothing rep
+  | isSafe rep = True
+  | otherwise = isSafeDamped (Just 0) rep
+isSafeDamped (Just x) rep
+  | x >= length rep = False
+  | isSafe $ deleteAt x rep = True
+  | otherwise = isSafeDamped (Just (x + 1)) rep
+
+part1 reps = 
+  length $ filter (isSafe) reps
+
+part2 reps = 
+  length $ filter (isSafeDamped Nothing) reps
+
+main = do
+  file <- readFile "day02.input"
+  let lns = map (splitOn " ") $ lines file
+  let reps = map (map (read::String->Int)) $ lns
+  putStrLn ("Part 1: " ++ (show $ part1 reps))
+  putStrLn ("Part 2: " ++ (show $ part2 reps))