add initial solution for day07

2 files changed, 37 insertions, 4 deletions

diff --git a/execs/Day06.hs b/execs/Day06.hs
index c35fd21..475f819 100644
--- a/execs/Day06.hs
+++ b/execs/Day06.hs
@@ -1,11 +1,8 @@
 
 module Main where
 
-import Data.Char (digitToInt)
-import Data.List (sort)
-import Data.Set (Set)
+import           Data.Set (Set)
 import qualified Data.Set as Set
-import Control.Monad
 
 parseLines :: [String] -> [String]
 parseLines allLines = unwords first : next
diff --git a/execs/Day07.hs b/execs/Day07.hs
new file mode 100644
index 0000000..1587e2b
--- /dev/null
+++ b/execs/Day07.hs
@@ -0,0 +1,36 @@
+module Main where
+
+import           Data.Map (Map)
+import qualified Data.Map as Map
+
+myBag = "shiny gold"
+
+parseContained :: [String] -> [(Int, String)]
+parseContained [] = []
+parseContained (count:b:c:_:rest) = (read count, unwords [b,c]):parseContained rest
+
+parseLine :: [String] -> (String, [(Int, String)])
+parseLine s = (leadingBag, contained)
+    where leadingBag = unwords $ take 2 s
+          trailingBags = drop 4 s
+          contained = case head trailingBags of
+                        "no" -> []
+                        _ -> parseContained trailingBags
+
+canContain :: Map String [(Int, String)] -> String -> Bool
+canContain m outer = myBag `elem` inners || any (canContain m) inners
+    where (Just inners) = map snd <$> Map.lookup outer m
+
+countNested :: String -> Map String [(Int, String)] -> Int
+countNested s m = if null l
+                     then 0
+                     else sum $ map counter l
+    where (Just l) = Map.lookup s m
+          counter (count, bag) = count + count * countNested bag m
+
+main :: IO ()
+main = do
+    n <- map (parseLine . words) . lines <$> readFile "input/07"
+    let q = Map.fromList n
+    print $ length $ filter (== True) $ map (canContain q . fst) $ Map.toList q
+    print $ countNested myBag q