30 lines
925 B
Haskell
30 lines
925 B
Haskell
{-# LANGUAGE OverloadedStrings #-}
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import Data.Char (isDigit)
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import Data.Either (rights)
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import Data.Maybe (fromJust)
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import Data.Text (Text)
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import qualified Data.Text as T (lines, stripPrefix)
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import qualified Data.Text.Read as T (decimal)
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import Lib (readFile')
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main :: IO ()
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main = do
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input <- rights . map parse . T.lines <$> readFile' "day4.in"
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putStr "Q1: "
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print $ q1 input
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putStr "Q2: "
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print $ q2 input
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parse :: Text -> Either String ((Int, Int), (Int, Int))
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parse rest = do
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(a, rest) <- T.decimal rest
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(b, rest) <- T.decimal $ fromJust $ T.stripPrefix "-" rest
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(c, rest) <- T.decimal $ fromJust $ T.stripPrefix "," rest
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(d, rest) <- T.decimal $ fromJust $ T.stripPrefix "-" rest
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return ((a, b), (c, d))
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q1, q2 :: [((Int, Int), (Int, Int))] -> Int
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q1 = length . filter (\((a, b), (c, d)) -> a >= c && b <= d || c >= a && d <= b)
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q2 = length . filter (\((a, b), (c, d)) -> b >= c && a <= d)
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