61 lines
1.5 KiB
Haskell
61 lines
1.5 KiB
Haskell
module Main where
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import System.Environment (getArgs)
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import Control.Exception (assert)
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import Text.Parsec (parse, many1, char, sepBy, endBy)
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import Text.Parsec.Char (endOfLine)
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import Text.ParserCombinators.Parsec (GenParser)
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import Text.ParserCombinators.Parsec.Number (decimal)
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type Report = [Level]
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type Level = Int
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reports :: GenParser Char st [Report]
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reports = endBy report endOfLine
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report :: GenParser Char st Report
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report = sepBy level (many1 (char ' '))
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level :: GenParser Char st Level
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level = decimal
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pairUp :: [a] -> [(a, a)]
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pairUp (a:b:tl) = (a, b) : pairUp (b:tl)
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pairUp _ = []
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isSafe :: Report -> Bool
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isSafe (a:b:tl) = a /= b && (==) 0 (
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length $ filter (not . (\(l, r) -> let
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dif = abs (l - r)
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cmp = if a < b then (<) else assert (b < a) (>)
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in (1 <= dif) && (dif <= 3) && l `cmp` r))
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$ pairUp
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$ a:b:tl)
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isSafe _ = True
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with1Removed :: Report -> [Report]
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with1Removed (h:tl) = tl : map (h :) (with1Removed tl)
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with1Removed [] = []
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isKindaSafe :: Report -> Bool
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isKindaSafe = any isSafe . with1Removed
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part1 :: [Report] -> Int
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part1 = length . filter isSafe
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part2 :: [Report] -> Int
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part2 = length . filter isKindaSafe
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main :: IO ()
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main = do
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args <- getArgs
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(fp:_) <- return args
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content <- readFile fp
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case parse reports fp content of
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Left e -> putStrLn ("Input file is incorrectly formatted : " ++ show e)
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Right r -> do
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putStrLn ("Solution (Part 1) : " ++ show (part1 r))
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putStrLn ("Solution (Part 2) : " ++ show (part2 r))
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