day3

day2/app/Pt2.hs

@@ -0,0 +1,45 @@
+module Main (main) where
+
+import Data.List (delete)
+import Text.Printf (printf)
+
+main :: IO ()
+main = do
+  inputs <- readFile "./inputs/day2"
+  let columns = map (map (read :: String -> Int) . words) (lines inputs)
+
+  -- print $ filter safe columns
+  printf "safe w damper: %d\n" $ length $ filter safe columns
+
+safe :: (Ord a, Num a) => [a] -> Bool
+safe x = distance x x x && ascOrDesc x
+
+distance :: (Ord a, Num a) => [a] -> [a] -> [a] -> Bool
+distance full arr (x : y : xs)
+  | length arr < length full - 1 = False
+  | abs (x - y) <= 3 && abs (x - y) >= 1 = distance full arr (y : xs)
+  | otherwise = distance full (delete y arr) (x : xs)
+distance full arr [_] = length arr >= length full - 1
+distance _ _ _ = False
+
+ascOrDesc :: (Ord a, Num a) => [a] -> Bool
+ascOrDesc (x : y : xs)
+  | x < y = asc (x : y : xs) (x : y : xs) (x : y : xs)
+  | x > y = desc (x : y : xs) (x : y : xs) (x : y : xs)
+ascOrDesc _ = False
+
+asc :: (Ord a, Num a) => [a] -> [a] -> [a] -> Bool
+asc full arr (x : y : xs)
+  | length arr < length full - 1 = False
+  | x < y = asc full arr (y : xs)
+  | x >= y = asc full (delete y arr) (x : xs)
+asc full arr [_] = length arr >= length full - 1
+asc _ _ _ = False
+
+desc :: (Ord a, Num a) => [a] -> [a] -> [a] -> Bool
+desc full arr (x : y : xs)
+  | length arr < length full - 1 = False
+  | x > y = desc full arr (y : xs)
+  | x <= y = desc full (delete y arr) (x : xs)
+desc full arr [_] = length arr >= length full - 1
+desc _ _ _ = False