Day 1: Secret Entrance

Megathread guidelines

  • Keep top level comments as only solutions, if you want to say something other than a solution put it in a new post. (replies to comments can be whatever)
  • You can send code in code blocks by using three backticks, the code, and then three backticks or use something such as https://topaz.github.io/paste/ if you prefer sending it through a URL

FAQ

  • Amy@piefed.blahaj.zoneEnglish
    2·
    22 days ago

    Haskell

    I was late to the part on this one and forgot to post my solution :3

    import Data.List  

readInput = map readMove . lines  
  where  
    readMove (d : ds) =  
      let n = read ds :: Int  
       in case d of  
            'L' -> -n  
            'R' -> n  

part1 = length . filter ((== 0) . (`mod` 100)) . scanl' (+) 50  

part2 = fst . foldl' count (0, 50)  
  where  
    count (z, p) d =  
      let (q, r) = (p + d) `divMod` 100  
          a = if p == 0 && d < 0 then -1 else 0  
          b = if r == 0 && d < 0 then 1 else 0  
       in (z + abs q + a + b, r)  

main = do  
  input <- readInput <$> readFile "input01"  
  print $ part1 input  
  print $ part2 input