Day03.hs

-- |
-- Module      : AOC2016.Day03
-- License     : BSD3
--
-- Stability   : experimental
-- Portability : non-portable
--
-- Day 3.  See "AOC.Solver" for the types used in this module!
module AOC2016.Day03 (
  day03a,
  day03b,
) where

import AOC.Solver ((:~>) (..))
import Data.List (sortBy, transpose)
import Data.List.Split (chunksOf)
import Text.Read (readMaybe)

isTriangle :: [Int] -> Bool
isTriangle (sortBy (flip compare) -> (x : xs)) = sum xs > x
isTriangle _ = False

day03a :: [[Int]] :~> Int
day03a =
  MkSol
    { sParse = traverse (traverse readMaybe . words) . lines
    , sShow = show
    , sSolve = Just . length . filter isTriangle
    }

day03b :: [[Int]] :~> _
day03b =
  MkSol
    { sParse = traverse (traverse readMaybe . words) . lines
    , sShow = show
    , sSolve =
        Just
          . length
          . filter isTriangle
          . concatMap transpose
          . chunksOf 3
    }