Day02

Author: opqdonut

Day02.hs

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+module Day02 where
+
+import Control.Applicative
+import Data.List
+import System.IO
+
+slurp :: IO [[Int]]
+slurp = map (map read . words) <$> lines <$> readFile "input-02"
+
+safe xs = all small diffs
+  where diffs = zipWith (-) (tail xs) xs
+        sign = signum (head diffs)
+        small d = signum d == sign && abs d >= 1 && abs d <= 3
+
+part1 = length . filter safe
+
+deletions [] = []
+deletions (x:xs) = xs:map (x:) (deletions xs)
+
+damped xs = any safe (deletions xs)
+
+part2 = length . filter damped
+
+main = do
+  --print =<< part1 <$> slurp
+  print =<< part2 <$> slurp