31 lines
1.1 KiB
Haskell
31 lines
1.1 KiB
Haskell
module Main (main) where
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import Control.Monad (when)
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import Data.List (foldl', sort)
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import System.Exit (die)
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exampleExpectedOutput = 35
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exampleExpectedOutput2 = 220
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parseInput :: String -> IO [Int]
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parseInput filename = do
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input <- readFile filename
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return $ map read $ lines input
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compute :: [Int] -> Int
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compute jolts = result $ foldl' compute' (0, 0, 0) $ sort jolts
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where
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compute' (prev, ones, threes) jolt
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| jolt - prev == 1 = (jolt, ones + 1, threes)
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| jolt - prev == 3 = (jolt, ones, threes + 1)
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result (_, ones, threes) = ones * (threes + 1)
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main :: IO ()
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main = do
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example <- parseInput "example"
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let exampleOutput = compute example
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when (exampleOutput /= exampleExpectedOutput) (die $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
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example2 <- parseInput "example2"
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let exampleOutput2 = compute example2
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when (exampleOutput2 /= exampleExpectedOutput2) (die $ "example2 failed: got " ++ show exampleOutput2 ++ " instead of " ++ show exampleExpectedOutput2)
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input <- parseInput "input"
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print $ compute input
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