Add 2019 day 6

y2019/src/Day6.hs

@@ -0,0 +1,51 @@
+module Day6 (day6) where
+
+import           Data.Maybe
+import qualified Data.Map as Map
+import           Data.List.Split
+import qualified Data.Set as Set
+
+-- https://stackoverflow.com/questions/22403029/how-to-zip-lists-with-different-length
+zipWithPadding :: a -> b -> [a] -> [b] -> [(a,b)]
+zipWithPadding a b (x:xs) (y:ys) = (x,y) : zipWithPadding a b xs ys
+zipWithPadding a _ []     ys     = zip (repeat a) ys
+zipWithPadding _ b xs     []     = zip xs (repeat b)
+
+orbitLength :: Map.Map String String -> String -> Int
+orbitLength orbits object
+  | isJust orbitOn = 1 + (orbitLength orbits (head (maybeToList orbitOn)))
+  | isNothing orbitOn = 0
+  where orbitOn = object `Map.lookup` orbits
+
+getOrbits :: Map.Map String String -> String -> [String]
+getOrbits orbits object
+  | isJust orbitOn = object:(getOrbits orbits (head (maybeToList orbitOn)))
+  | isNothing orbitOn = object:[]
+  where orbitOn = object `Map.lookup` orbits
+
+countTuples :: [(String, String)] -> Int
+countTuples (("", _):xs) = 1 + countTuples xs
+countTuples ((_, ""):xs) = 1 + countTuples xs
+countTuples ((_, _):xs) = 2 + countTuples xs
+countTuples [] = 0
+
+day6 :: IO ()
+day6 = do
+  putStrLn "AoC 2019 day 6"
+  putStr "Input >"
+  input <- getContents
+  putStrLn ""
+
+  -- 1 orbits 2
+  let orbitsMap = Map.fromList (map (\r -> (r !! 1, r !! 0)) (map (splitOn ")") (lines input)))
+  let orbitingObjects = Map.keysSet orbitsMap
+
+  let nbOrbitsPerObject = map (orbitLength orbitsMap) (Set.toList orbitingObjects)
+
+  putStrLn $ "Part 1: " ++ (show (sum nbOrbitsPerObject))
+
+  let myOrbits = reverse (tail (getOrbits orbitsMap "YOU"))
+  let santaOrbits = reverse (tail (getOrbits orbitsMap "SAN"))
+
+  let elems = dropWhile (\(a, b) -> a == b) (zipWithPadding [] [] myOrbits santaOrbits)
+  putStrLn $ "Part 2: " ++ (show (countTuples elems))

y2019/src/DayPicker.hs

@@ -10,6 +10,7 @@ import Day2
 import Day3
 import Day4
 import Day5
+import Day6
 
 -- TODO Better way?
 load :: [String] -> IO ()
@@ -19,6 +20,7 @@ load ("2":_) = day2
 load ("3":_) = day3
 load ("4":_) = day4
 load ("5":_) = day5
+load ("6":_) = day6
 load _ = putStrLn "Unavailable date"
 
 dayPicker :: IO ()