advent-of-code/2020/10-Adapter_Array/second.hs

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2023-03-20 00:35:17 +01:00
module Main (main) where
import Control.Monad (when)
import Data.List (group, sort)
import System.Exit (die)
exampleExpectedOutput = 8
exampleExpectedOutput2 = 19208
parseInput :: String -> IO [Int]
parseInput filename = do
input <- readFile filename
return $ map read $ lines input
compute :: [Int] -> Int
compute jolts = product $ map (([0, 1, 2, 4, 7] !!) . length) $ filter ((==) 1 . head) $ group $ zipWith (-) s (0 : s)
where
s = sort jolts
main :: IO ()
main = do
example <- parseInput "example"
let s = sort example
let exampleOutput = compute example
when (exampleOutput /= exampleExpectedOutput) (die $ "example failed: got " ++ show exampleOutput ++ " instead of " ++ show exampleExpectedOutput)
example2 <- parseInput "example2"
let exampleOutput2 = compute example2
when (exampleOutput2 /= exampleExpectedOutput2) (die $ "example2 failed: got " ++ show exampleOutput2 ++ " instead of " ++ show exampleExpectedOutput2)
input <- parseInput "input"
print $ compute input