aoc2020/day5/day5.hs

24 lines
688 B
Haskell
Raw Normal View History

2020-12-05 10:21:57 +01:00
import AoC
import Data.List (sort)
import Data.Maybe (fromJust)
import Numeric (readInt)
import Text.ParserCombinators.ReadP
binarify :: String -> Maybe Int
binarify = oneCompleteResult . readS_to_P $ readInt 2 (`elem` "BFLR") digitValue
where digitValue 'F' = 0
digitValue 'B' = 1
digitValue 'L' = 0
digitValue 'R' = 1
findHole :: (Enum a, Eq a) => [a] -> Maybe a
findHole (x:y:ys) | y == next = findHole $ y:ys
| otherwise = Just next
where next = succ x
findHole _ = Nothing
2020-12-06 07:37:17 +01:00
main = runAoC (map (fromJust . binarify) . lines) part1 part2
2020-12-05 10:21:57 +01:00
where part1 = foldr1 max
part2 = fromJust . findHole . sort