15 lines
559 B
Haskell
15 lines
559 B
Haskell
module Day1B where
|
|
|
|
import Day1A (read')
|
|
import qualified Data.IntSet as S
|
|
|
|
handle :: Int -> S.IntSet -> [Int] -> Int
|
|
handle freq history (nextDelta:xs)
|
|
| S.member freq history = freq -- When the frequency is in the history set, return it
|
|
| otherwise = handle (freq + nextDelta) (S.insert freq history) xs -- Recurse otherwise
|
|
handle _ _ _ = error "xs should not be empty :("
|
|
|
|
main :: IO ()
|
|
main = interact $ show . handle 0 S.empty . deltaFreqs
|
|
where deltaFreqs = cycle . map read' . lines -- Convert input to Ints and repeat infinitely
|