2020/1.hs


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module Main where

import Data.List (find)
import Data.Maybe (fromJust)
import qualified Data.Set as Set

import Input


main :: IO ()
main = do
    input <- map read <$> getInput 1 :: IO [Int]

    let num1 = fromJust (find ((`Set.member` Set.fromList input) . (2020 -)) input)
    print (num1 * (2020 - num1))

    let pair = snd (fromJust (find ((`Set.member` Set.fromList input) . (2020 -) . fst)
                                   [(a + b, (a, b)) | a <- input, b <- input]))
    print (fst pair * snd pair * (2020 - fst pair - snd pair))