aoc-2020-day6

p1.hs

{-# LANGUAGE OverloadedStrings #-}

module Main where

import qualified Data.Text as T
import qualified Data.Text.IO as TIO
import Data.List.NonEmpty (groupAllWith)

groups = map (T.replace "\n" "") . T.splitOn "\n\n"

distinctAnswerCount = length . groupAllWith id . T.unpack

main = do
  raw <- TIO.readFile "./d6.txt"
  print $ sum $ map distinctAnswerCount $ groups raw

p2.hs

{-# LANGUAGE OverloadedStrings #-}

module Main where

import qualified Data.Text as T
import qualified Data.Text.IO as TIO
import Data.List.NonEmpty (groupAllWith)
import Data.Bifunctor

dupe a = (a, a)

groups = map countPeopleJoinAnswers . T.splitOn "\n\n" . T.strip

  where
    countPeopleJoinAnswers = bimap ((+ 1) . T.count "\n") (T.replace "\n" "") . dupe

allAnswered =
  concatMap $ uncurry (filter . (==)) . second (map length . groupAllWith id . T.unpack)

main = do
  raw <- TIO.readFile "./d6.txt"
  print $ length $ allAnswered $ groups raw