feat(day2): Fuck it we ball

day2/Main.hs

@@ -2,6 +2,8 @@ module Main where
 
 import System.Environment (getArgs)
 
+import Control.Exception (assert)
+
 import Text.Parsec (parse, many1, char, sepBy, endBy)
 import Text.Parsec.Char (endOfLine)
 import Text.ParserCombinators.Parsec (GenParser)
@@ -23,28 +25,28 @@ pairUp :: [a] -> [(a, a)]
 pairUp (a:b:tl) = (a, b) : pairUp (b:tl)
 pairUp _ = []
 
-allIncOrDec :: Bool -> Report -> Bool
-allIncOrDec dampened (a:b:tl) = if a /= b
-    then (if dampened then (>=) 0 else (==) 0)
-        $ length
-        $ filter (not . uncurry (if a < b then (<) else (>)))
+isSafe :: Report -> Bool
+isSafe (a:b:tl) = a /= b && (==) 0 (
+    length $ filter (not . (\(l, r) -> let
+                dif = abs (l - r)
+                cmp = if a < b then (<) else assert (b < a) (>)
+            in (1 <= dif) && (dif <= 3) && l `cmp` r))
         $ pairUp
-        $ b:tl
-    else dampened && allIncOrDec False (b:tl)
-allIncOrDec _ _ = True
+        $ a:b:tl)
+isSafe _ = True
 
-notTooDifferent :: Bool -> Report -> Bool
-notTooDifferent dampened (a:b:tl) =
-    let dif = abs (a - b)
-    in if (1 <= dif) && (dif <= 3)
-        then notTooDifferent dampened (b:tl)
-        else dampened && notTooDifferent False (b:tl)
-notTooDifferent _ _ = True
+with1Removed :: Report -> [Report]
+with1Removed (h:tl) = tl : map (h :) (with1Removed tl)
+with1Removed [] = []
 
-solve :: Bool -> [Report] -> Int
-solve dampened = length
-    . filter (allIncOrDec dampened)
-    . filter (notTooDifferent dampened)
+isKindaSafe :: Report -> Bool
+isKindaSafe = any isSafe . with1Removed
+
+part1 :: [Report] -> Int
+part1 = length . filter isSafe
+
+part2 :: [Report] -> Int
+part2 = length . filter isKindaSafe
 
 main :: IO ()
 main = do
@@ -54,5 +56,5 @@ main = do
     case parse reports fp content of
         Left e -> putStrLn ("Input file is incorrectly formatted : " ++ show e)
         Right r -> do
-            putStrLn ("Solution (Part 1) : " ++ show (solve False r))
-            putStrLn ("Solution (Part 2) : " ++ show (solve True r))
+            putStrLn ("Solution (Part 1) : " ++ show (part1 r))
+            putStrLn ("Solution (Part 2) : " ++ show (part2 r))