Add 2020 day 7

haskellAoC/src/Y2020/Day07.hs

@@ -0,0 +1,48 @@
+module Y2020.Day07 (y20day07) where
+
+import Data.List
+import Data.List.Split
+
+import Debug.Trace
+
+type BagContents = [(Int, String)]
+type Bag = (String, BagContents)
+type Bags = [Bag]
+
+cleanBag :: String -> (Int, String)
+cleanBag input = (qty, name)
+  where qty = read $ ((splitOn " " input) !! 0)
+        name = tail $ dropWhile (/= ' ') ((splitOn " bag" input) !! 0)
+
+parseBagContents :: String -> BagContents
+parseBagContents "no other bags." = []
+parseBagContents input = map cleanBag input'
+  where input' = splitOn ", " input
+
+parseLine :: String -> Bag
+parseLine input = (bag_name, bag_contents)
+  where input' = splitOn " contain " input
+        bag_name = (splitOn " bags" (input' !! 0)) !! 0
+        bag_contents = parseBagContents (input' !! 1)
+
+getContaining :: Bags -> String -> [String]
+getContaining bags name = map fst $ filter containsBag $ bags
+  where containsBag bag = (>= 1) $ length $ filter (== name) $ map snd $ snd bag
+
+getBagsContainers :: Bags -> [String] -> [String]
+getBagsContainers bags input
+  | input == output = input
+  | otherwise = getBagsContainers bags output
+  where output = nub $ input ++ concatMap (getContaining bags) input
+
+getBagContents :: Bags -> String -> Int
+getBagContents bags name = 1 + qty
+  where bag = head $ filter ((== name) . fst) bags :: Bag
+        qty = sum $ map countBagContents $ snd bag
+        countBagContents (nb, bg) = nb * (getBagContents bags bg)
+
+y20day07 :: [String] -> (String, String)
+y20day07 input = (part1, part2)
+  where part1 = show $ (+ (-1)) $ length $ getBagsContainers bags ["shiny gold"]
+        part2 = show $ (+ (-1)) $ getBagContents bags "shiny gold"
+        bags = map parseLine input

haskellAoC/src/Y2020/Days.hs

@@ -6,7 +6,7 @@ import Y2020.Day03
 import Y2020.Day04
 import Y2020.Day05
 import Y2020.Day06
-
+import Y2020.Day07
 
 year2020 :: String -> [String] -> (String, String)
 year2020 "01" = y20day01
@@ -15,3 +15,4 @@ year2020 "03" = y20day03
 year2020 "04" = y20day04
 year2020 "05" = y20day05
 year2020 "06" = y20day06
+year2020 "07" = y20day07