aoc2022.cabal

@@ -39,6 +39,10 @@ library
       Day4.Part1
       Day4.Part2
       Day4.Shared
+      Day5
+      Day5.Part1
+      Day5.Part2
+      Day5.Shared
       Lib
   other-modules:
       Paths_aoc2022
@@ -55,6 +59,7 @@ library
     , lens
     , split
     , text
+    , these
   default-language: Haskell2010
 
 executable aoc2022-exe
@@ -75,6 +80,7 @@ executable aoc2022-exe
     , lens
     , split
     , text
+    , these
   default-language: Haskell2010
 
 test-suite aoc2022-test
@@ -85,6 +91,7 @@ test-suite aoc2022-test
       Day2Spec
       Day3Spec
       Day4Spec
+      Day5Spec
       Paths_aoc2022
   hs-source-dirs:
       test
@@ -100,4 +107,5 @@ test-suite aoc2022-test
     , lens
     , split
     , text
+    , these
   default-language: Haskell2010

package.yaml

@@ -30,6 +30,7 @@ dependencies:
 - split
 - lens
 - Ranged-sets
+- these
 
 ghc-options:
 - -Wall

ressources/day05-input

@@ -0,0 +1,511 @@
+        [J]         [B]     [T]
+        [M] [L]     [Q] [L] [R]
+        [G] [Q]     [W] [S] [B] [L]
+[D]     [D] [T]     [M] [G] [V] [P]
+[T]     [N] [N] [N] [D] [J] [G] [N]
+[W] [H] [H] [S] [C] [N] [R] [W] [D]
+[N] [P] [P] [W] [H] [H] [B] [N] [G]
+[L] [C] [W] [C] [P] [T] [M] [Z] [W]
+ 1   2   3   4   5   6   7   8   9
+
+move 6 from 6 to 5
+move 2 from 5 to 9
+move 8 from 9 to 1
+move 3 from 5 to 4
+move 9 from 1 to 8
+move 2 from 1 to 5
+move 1 from 1 to 8
+move 14 from 8 to 2
+move 1 from 1 to 2
+move 2 from 6 to 8
+move 2 from 5 to 7
+move 6 from 8 to 6
+move 4 from 4 to 2
+move 2 from 4 to 9
+move 5 from 7 to 4
+move 2 from 7 to 5
+move 6 from 2 to 4
+move 2 from 4 to 7
+move 4 from 5 to 8
+move 1 from 5 to 2
+move 3 from 3 to 5
+move 3 from 8 to 3
+move 4 from 3 to 7
+move 2 from 9 to 8
+move 1 from 3 to 7
+move 1 from 6 to 8
+move 5 from 7 to 1
+move 3 from 7 to 2
+move 1 from 6 to 3
+move 2 from 5 to 9
+move 5 from 4 to 2
+move 3 from 5 to 9
+move 5 from 9 to 6
+move 2 from 1 to 3
+move 4 from 4 to 1
+move 2 from 8 to 1
+move 18 from 2 to 5
+move 3 from 4 to 1
+move 1 from 1 to 2
+move 1 from 6 to 8
+move 1 from 7 to 1
+move 10 from 1 to 5
+move 1 from 1 to 5
+move 3 from 8 to 1
+move 2 from 1 to 5
+move 3 from 6 to 5
+move 8 from 2 to 9
+move 2 from 9 to 7
+move 3 from 3 to 8
+move 1 from 4 to 8
+move 3 from 5 to 3
+move 15 from 5 to 8
+move 4 from 6 to 1
+move 2 from 7 to 4
+move 9 from 5 to 7
+move 1 from 6 to 8
+move 5 from 3 to 5
+move 5 from 7 to 5
+move 3 from 1 to 5
+move 2 from 4 to 8
+move 3 from 1 to 6
+move 20 from 5 to 4
+move 1 from 7 to 6
+move 21 from 8 to 2
+move 1 from 3 to 7
+move 2 from 4 to 2
+move 1 from 7 to 1
+move 18 from 2 to 8
+move 3 from 9 to 2
+move 1 from 6 to 4
+move 1 from 1 to 9
+move 8 from 8 to 6
+move 4 from 8 to 2
+move 1 from 2 to 6
+move 7 from 8 to 5
+move 2 from 5 to 3
+move 1 from 9 to 5
+move 5 from 2 to 4
+move 1 from 3 to 7
+move 2 from 5 to 7
+move 4 from 4 to 9
+move 2 from 5 to 9
+move 6 from 2 to 8
+move 3 from 7 to 3
+move 2 from 5 to 4
+move 4 from 8 to 2
+move 2 from 7 to 4
+move 7 from 6 to 4
+move 1 from 8 to 4
+move 3 from 6 to 7
+move 2 from 7 to 2
+move 7 from 9 to 7
+move 1 from 9 to 2
+move 3 from 3 to 6
+move 3 from 7 to 4
+move 2 from 7 to 9
+move 6 from 4 to 1
+move 3 from 7 to 9
+move 1 from 8 to 5
+move 1 from 3 to 6
+move 3 from 9 to 4
+move 2 from 6 to 4
+move 3 from 9 to 1
+move 4 from 2 to 8
+move 1 from 8 to 5
+move 9 from 1 to 2
+move 1 from 6 to 5
+move 1 from 7 to 2
+move 1 from 8 to 1
+move 2 from 8 to 9
+move 1 from 9 to 8
+move 1 from 5 to 7
+move 1 from 7 to 6
+move 1 from 9 to 8
+move 1 from 6 to 3
+move 26 from 4 to 3
+move 1 from 5 to 8
+move 3 from 6 to 3
+move 7 from 4 to 3
+move 1 from 1 to 3
+move 1 from 4 to 8
+move 13 from 3 to 1
+move 1 from 3 to 4
+move 12 from 2 to 5
+move 20 from 3 to 2
+move 1 from 4 to 1
+move 4 from 5 to 7
+move 1 from 7 to 8
+move 9 from 5 to 2
+move 5 from 1 to 5
+move 21 from 2 to 8
+move 5 from 8 to 4
+move 4 from 5 to 2
+move 6 from 1 to 7
+move 1 from 5 to 4
+move 4 from 3 to 1
+move 6 from 1 to 3
+move 1 from 1 to 9
+move 6 from 8 to 7
+move 4 from 8 to 2
+move 4 from 2 to 7
+move 5 from 4 to 1
+move 8 from 8 to 4
+move 1 from 9 to 6
+move 18 from 7 to 6
+move 15 from 6 to 5
+move 2 from 6 to 8
+move 2 from 6 to 3
+move 8 from 3 to 7
+move 15 from 5 to 7
+move 3 from 4 to 9
+move 12 from 2 to 3
+move 3 from 9 to 4
+move 6 from 7 to 9
+move 9 from 4 to 5
+move 10 from 3 to 5
+move 9 from 5 to 2
+move 14 from 7 to 8
+move 14 from 8 to 5
+move 4 from 2 to 4
+move 1 from 4 to 6
+move 2 from 8 to 4
+move 3 from 8 to 9
+move 18 from 5 to 1
+move 1 from 5 to 9
+move 1 from 7 to 4
+move 5 from 5 to 9
+move 3 from 2 to 4
+move 13 from 9 to 2
+move 13 from 2 to 6
+move 1 from 7 to 3
+move 3 from 3 to 1
+move 9 from 6 to 5
+move 1 from 7 to 8
+move 20 from 1 to 8
+move 2 from 2 to 8
+move 5 from 6 to 9
+move 15 from 8 to 7
+move 3 from 5 to 3
+move 5 from 1 to 3
+move 2 from 3 to 4
+move 3 from 9 to 5
+move 4 from 5 to 2
+move 4 from 5 to 7
+move 3 from 4 to 9
+move 10 from 7 to 8
+move 2 from 9 to 4
+move 1 from 5 to 6
+move 8 from 7 to 9
+move 1 from 6 to 7
+move 6 from 3 to 4
+move 12 from 9 to 8
+move 1 from 1 to 5
+move 2 from 7 to 8
+move 1 from 7 to 5
+move 1 from 9 to 5
+move 2 from 2 to 9
+move 11 from 8 to 1
+move 7 from 1 to 5
+move 3 from 1 to 6
+move 5 from 8 to 9
+move 8 from 4 to 3
+move 4 from 4 to 6
+move 5 from 9 to 3
+move 4 from 4 to 5
+move 2 from 6 to 7
+move 1 from 9 to 5
+move 2 from 7 to 4
+move 12 from 5 to 2
+move 8 from 8 to 9
+move 8 from 8 to 6
+move 9 from 6 to 2
+move 4 from 9 to 2
+move 1 from 5 to 1
+move 5 from 2 to 1
+move 2 from 5 to 4
+move 5 from 2 to 5
+move 5 from 5 to 6
+move 3 from 4 to 7
+move 11 from 2 to 7
+move 2 from 2 to 1
+move 4 from 3 to 7
+move 2 from 2 to 4
+move 6 from 1 to 4
+move 1 from 2 to 8
+move 2 from 9 to 5
+move 4 from 4 to 3
+move 5 from 4 to 1
+move 2 from 2 to 1
+move 1 from 8 to 5
+move 14 from 7 to 6
+move 3 from 9 to 2
+move 15 from 6 to 8
+move 4 from 1 to 3
+move 2 from 2 to 3
+move 1 from 1 to 7
+move 2 from 3 to 5
+move 4 from 5 to 4
+move 1 from 3 to 5
+move 5 from 1 to 6
+move 12 from 6 to 7
+move 7 from 8 to 4
+move 12 from 7 to 9
+move 4 from 7 to 9
+move 1 from 2 to 8
+move 12 from 9 to 4
+move 23 from 4 to 3
+move 1 from 6 to 5
+move 3 from 9 to 3
+move 1 from 7 to 9
+move 1 from 9 to 1
+move 1 from 9 to 7
+move 42 from 3 to 1
+move 3 from 5 to 4
+move 5 from 1 to 3
+move 3 from 4 to 7
+move 1 from 1 to 9
+move 4 from 3 to 8
+move 1 from 3 to 7
+move 1 from 9 to 1
+move 2 from 7 to 8
+move 8 from 1 to 6
+move 2 from 7 to 5
+move 9 from 1 to 2
+move 5 from 2 to 3
+move 3 from 2 to 4
+move 20 from 1 to 2
+move 1 from 1 to 5
+move 1 from 6 to 7
+move 3 from 4 to 7
+move 2 from 3 to 6
+move 3 from 6 to 1
+move 1 from 6 to 4
+move 2 from 1 to 6
+move 3 from 5 to 9
+move 1 from 4 to 3
+move 2 from 7 to 4
+move 6 from 8 to 4
+move 1 from 1 to 9
+move 1 from 2 to 9
+move 2 from 8 to 7
+move 3 from 6 to 2
+move 5 from 7 to 5
+move 4 from 2 to 5
+move 4 from 4 to 6
+move 3 from 9 to 6
+move 4 from 3 to 1
+move 1 from 9 to 2
+move 7 from 8 to 9
+move 4 from 2 to 4
+move 2 from 1 to 7
+move 3 from 4 to 5
+move 4 from 2 to 4
+move 1 from 7 to 4
+move 4 from 2 to 9
+move 7 from 4 to 3
+move 1 from 7 to 3
+move 6 from 2 to 3
+move 2 from 1 to 5
+move 10 from 3 to 6
+move 2 from 6 to 1
+move 2 from 2 to 7
+move 2 from 3 to 1
+move 1 from 7 to 8
+move 11 from 5 to 3
+move 2 from 3 to 1
+move 4 from 6 to 1
+move 1 from 4 to 6
+move 8 from 3 to 4
+move 2 from 5 to 6
+move 3 from 3 to 5
+move 1 from 8 to 4
+move 1 from 4 to 9
+move 2 from 6 to 1
+move 1 from 5 to 1
+move 9 from 4 to 3
+move 5 from 6 to 9
+move 5 from 6 to 7
+move 13 from 9 to 3
+move 5 from 1 to 8
+move 4 from 8 to 4
+move 10 from 3 to 2
+move 3 from 6 to 1
+move 2 from 7 to 9
+move 1 from 8 to 3
+move 1 from 7 to 3
+move 1 from 9 to 5
+move 1 from 6 to 3
+move 7 from 2 to 4
+move 3 from 5 to 2
+move 8 from 3 to 5
+move 7 from 4 to 3
+move 5 from 9 to 7
+move 1 from 7 to 1
+move 9 from 1 to 8
+move 9 from 5 to 8
+move 2 from 7 to 8
+move 3 from 8 to 1
+move 10 from 3 to 6
+move 1 from 1 to 6
+move 5 from 1 to 7
+move 3 from 2 to 8
+move 7 from 8 to 6
+move 7 from 8 to 6
+move 1 from 3 to 5
+move 5 from 7 to 9
+move 4 from 8 to 4
+move 3 from 2 to 8
+move 1 from 7 to 8
+move 3 from 3 to 9
+move 3 from 7 to 4
+move 1 from 7 to 2
+move 9 from 9 to 1
+move 5 from 1 to 9
+move 4 from 8 to 6
+move 1 from 2 to 7
+move 1 from 5 to 3
+move 1 from 3 to 7
+move 1 from 1 to 9
+move 1 from 1 to 7
+move 5 from 9 to 6
+move 2 from 7 to 6
+move 10 from 4 to 8
+move 1 from 4 to 2
+move 1 from 4 to 1
+move 1 from 9 to 2
+move 3 from 1 to 2
+move 1 from 7 to 3
+move 1 from 2 to 1
+move 16 from 6 to 3
+move 9 from 6 to 1
+move 6 from 6 to 1
+move 5 from 6 to 1
+move 3 from 8 to 1
+move 11 from 3 to 4
+move 1 from 6 to 2
+move 3 from 8 to 2
+move 4 from 1 to 6
+move 5 from 3 to 2
+move 1 from 2 to 5
+move 1 from 8 to 5
+move 5 from 8 to 3
+move 4 from 6 to 9
+move 2 from 9 to 6
+move 3 from 3 to 9
+move 1 from 5 to 7
+move 5 from 1 to 6
+move 3 from 6 to 4
+move 2 from 2 to 9
+move 8 from 4 to 2
+move 9 from 1 to 7
+move 3 from 3 to 5
+move 3 from 5 to 7
+move 12 from 7 to 1
+move 5 from 4 to 6
+move 1 from 4 to 5
+move 7 from 1 to 8
+move 5 from 9 to 3
+move 1 from 7 to 4
+move 10 from 1 to 8
+move 1 from 4 to 8
+move 4 from 6 to 8
+move 1 from 6 to 9
+move 2 from 5 to 1
+move 4 from 3 to 4
+move 1 from 1 to 8
+move 4 from 4 to 7
+move 2 from 1 to 8
+move 4 from 6 to 1
+move 3 from 9 to 5
+move 1 from 6 to 5
+move 1 from 3 to 7
+move 24 from 8 to 6
+move 3 from 6 to 5
+move 4 from 6 to 7
+move 1 from 1 to 7
+move 7 from 7 to 6
+move 7 from 5 to 3
+move 13 from 6 to 8
+move 3 from 1 to 2
+move 7 from 6 to 3
+move 12 from 2 to 4
+move 4 from 6 to 9
+move 6 from 3 to 1
+move 1 from 2 to 4
+move 2 from 8 to 7
+move 2 from 2 to 9
+move 6 from 3 to 4
+move 12 from 8 to 2
+move 18 from 2 to 5
+move 10 from 4 to 3
+move 4 from 7 to 3
+move 5 from 4 to 7
+move 3 from 5 to 2
+move 4 from 7 to 9
+move 1 from 5 to 4
+move 3 from 2 to 1
+move 4 from 3 to 6
+move 7 from 5 to 6
+move 2 from 5 to 7
+move 5 from 1 to 7
+move 9 from 7 to 6
+move 8 from 9 to 8
+move 1 from 1 to 3
+move 1 from 3 to 1
+move 10 from 3 to 9
+move 8 from 8 to 4
+move 1 from 3 to 8
+move 1 from 1 to 3
+move 6 from 9 to 1
+move 5 from 5 to 3
+move 5 from 3 to 6
+move 1 from 8 to 9
+move 19 from 6 to 2
+move 13 from 4 to 1
+move 4 from 1 to 5
+move 6 from 2 to 1
+move 2 from 9 to 4
+move 1 from 3 to 1
+move 9 from 2 to 3
+move 4 from 5 to 1
+move 5 from 9 to 6
+move 4 from 3 to 4
+move 3 from 2 to 7
+move 2 from 4 to 8
+move 6 from 1 to 9
+move 1 from 8 to 6
+move 4 from 1 to 5
+move 3 from 4 to 5
+move 1 from 7 to 2
+move 11 from 1 to 6
+move 1 from 2 to 7
+move 5 from 3 to 7
+move 1 from 3 to 4
+move 1 from 4 to 8
+move 3 from 5 to 6
+move 8 from 1 to 7
+move 1 from 8 to 9
+move 1 from 6 to 9
+move 1 from 8 to 5
+move 11 from 6 to 5
+move 12 from 5 to 2
+move 1 from 5 to 2
+move 8 from 7 to 3
+move 1 from 5 to 6
+move 2 from 5 to 6
+move 3 from 7 to 1
+move 6 from 2 to 6
+move 1 from 3 to 1
+move 1 from 4 to 1
+move 4 from 6 to 2
+move 5 from 1 to 5
+move 10 from 2 to 3
+move 2 from 9 to 4
+move 4 from 5 to 8
+move 2 from 2 to 7
+move 12 from 6 to 7
+move 1 from 8 to 2
+move 10 from 3 to 4
+move 2 from 3 to 5
+move 1 from 3 to 1

src/Day5.hs

@@ -0,0 +1,14 @@
+module Day5 (day5) where
+
+import Day5.Part1
+import Day5.Part2
+
+
+day5 :: IO ()
+day5 = do
+   input <- readFile "ressources/day05-input"
+   putStrLn "Day5"
+   let message = day5_1 input
+   putStrLn ("Message from crates: " ++ message)
+   let secondMessage = day5_2 input
+   putStrLn ("Actuale message from crates: " ++ secondMessage)

src/Day5/Part1.hs

@@ -0,0 +1,25 @@
+module Day5.Part1 (
+  executeOperation,
+  day5_1
+) where
+
+import qualified Data.Sequence as S
+import Data.Foldable (toList)
+import Day5.Shared
+
+executeOperation :: Row -> Operation -> Row
+executeOperation row op
+  | count op == 1 = updatedRow
+  | otherwise = executeOperation updatedRow (Operation { count = count op - 1, from = from op, to = to op })
+  where
+    originStack = row `S.index` asInt (from op)
+    targetStack = row `S.index` asInt (to op)
+    movedContent = head $ content originStack
+    updatedOrigin = Stack (drop 1 $ content originStack)
+    updatedTarget = Stack (movedContent : content targetStack)
+    updatedRow = S.update (asInt $ to op) updatedTarget $ S.update (asInt $ from op) updatedOrigin row
+
+day5_1 :: String -> String
+day5_1 input = toList . findTopOfStacks $ foldl executeOperation row operations
+  where
+    (row, operations) = parseInput input

src/Day5/Part2.hs

@@ -0,0 +1,24 @@
+module Day5.Part2 (
+  execute9001Operation,
+  day5_2
+) where
+
+import qualified Data.Sequence as S
+import Data.Foldable (toList)
+import Day5.Shared
+
+execute9001Operation :: Row -> Operation -> Row
+execute9001Operation row op
+  = updatedRow 
+  where
+    originStack = row `S.index` asInt (from op)
+    targetStack = row `S.index` asInt (to op)
+    movedContent = take (count op) $ content originStack
+    updatedOrigin = Stack (drop (count op) $ content originStack)
+    updatedTarget = Stack (movedContent ++ content targetStack)
+    updatedRow = S.update (asInt $ to op) updatedTarget $ S.update (asInt $ from op) updatedOrigin row
+
+day5_2 :: String -> String
+day5_2 input = toList . findTopOfStacks $ foldl execute9001Operation row operations
+  where
+    (row, operations) = parseInput input

src/Day5/Shared.hs

@@ -0,0 +1,84 @@
+module Day5.Shared (
+  StackIndex (..),
+  Operation (..),
+  Stack (..),
+  Row,
+  Content,
+  asInt,
+  content,
+  parseOperation,
+  parseStacks,
+  parseRow,
+  combineRows,
+  parseInput,
+  zipWithPadding,
+  findTopOfStacks
+) where
+
+import qualified Data.Sequence as S
+import Data.Sequence (Seq (..))
+
+newtype StackIndex = StackIndex Int deriving (Show, Eq, Ord)
+asInt :: StackIndex -> Int
+asInt (StackIndex i) = i - 1
+
+data Operation = Operation
+                    { count :: Int
+                    , from :: StackIndex
+                    , to :: StackIndex} deriving (Show, Eq)
+
+type Content = Char
+newtype Stack = Stack [Content] deriving (Show, Eq)
+
+content :: Stack  -> [Content]
+content (Stack c) = c
+
+instance Semigroup Stack where
+  (Stack x) <> (Stack y) = Stack (x ++ y)
+
+instance Monoid Stack where
+  mempty = Stack []
+
+type Row = S.Seq Stack
+
+parseOperation :: String -> Operation
+parseOperation line = Operation {
+ count = read $ parts !! 1,
+  from = StackIndex (read $ parts !! 3),
+  to = StackIndex (read $ parts !! 5)
+  }
+  where
+    parts = words line
+
+parseStacks :: [String] -> Row
+parseStacks input = foldl combineRows S.empty rows
+  where
+    rows = map parseRow input
+
+parseRow :: String -> Row
+parseRow ('[':c:']':' ':cs) = Stack [c] :<| parseRow cs
+parseRow (' ':' ':' ':' ':cs) = Stack [] :<| parseRow cs
+parseRow ['[', c, ']'] = S.singleton $ Stack [c]
+parseRow [' ', ' ', ' '] = S.singleton $ Stack []
+parseRow (' ':'1':_) = S.empty -- skip last line
+parseRow cs = error ("parseRow: unexpected Row \"" ++ cs ++ "\"")
+
+combineRows :: Row -> Row -> Row
+combineRows S.Empty row = row
+combineRows row S.Empty = row
+combineRows up down = S.fromList [x <> y | (x,y) <- zipWithPadding up down]
+
+zipWithPadding :: (Monoid a, Monoid b) => S.Seq a -> S.Seq b -> [(a,b)]
+zipWithPadding (x :<| xs)  (y :<| ys)  = (x,y) : zipWithPadding xs ys
+zipWithPadding S.Empty (y :<| ys)  = (mempty, y) : zipWithPadding S.empty ys
+zipWithPadding (x :<| xs)  S.Empty = (x, mempty) : zipWithPadding xs S.empty
+zipWithPadding S.Empty  S.Empty = []
+
+parseInput :: String -> (Row, [Operation])
+parseInput input = (parseStacks stackInput, map parseOperation (drop 1 operationInput))
+  where
+    (stackInput, operationInput) = break ("" ==) $ lines input
+
+
+findTopOfStacks :: Row -> Seq Content
+findTopOfStacks row = head . content <$> row

src/Lib.hs

@@ -2,8 +2,8 @@ module Lib
     ( someFunc
     ) where
       
-import Day4      
+import Day5      
 
 someFunc :: IO ()
-someFunc = day4
+someFunc = day5
 

test/Day5Spec.hs

@@ -0,0 +1,84 @@
+{-# LANGUAGE QuasiQuotes #-}
+module Day5Spec (spec) where
+
+import Test.Hspec
+import Text.Heredoc
+import qualified Data.Sequence as S
+
+import Day5.Part1
+import Day5.Part2
+import Day5.Shared
+
+inputPart1 :: String
+inputPart1 = [str|    [D]
+                 |[N] [C]
+                 |[Z] [M] [P]
+                 | 1   2   3
+                 |
+                 |move 1 from 2 to 1
+                 |move 3 from 1 to 3
+                 |move 2 from 2 to 1
+                 |move 1 from 1 to 2
+                 |]
+
+inputStacks :: String
+inputStacks = [str|    [D]
+                  |[N] [C]
+                  |[Z] [M] [P]
+                  | 1   2   3
+                  |]
+
+inputOperations :: String
+inputOperations = [str|move 1 from 2 to 1
+                      |move 3 from 1 to 3
+                      |move 2 from 2 to 1
+                      |move 1 from 1 to 2
+                      |]
+spec :: Spec
+spec =
+  describe "Day5" $ do
+    describe "Part1" $ do
+      it "parses Operations" $ do
+        let operation = head . lines $ inputOperations
+        parseOperation operation `shouldBe` Operation { count = 1, from = StackIndex 2, to = StackIndex 1 }
+      it "parses stacks" $ do
+        parseStacks (lines inputStacks) `shouldBe` S.fromList [Stack "NZ", Stack "DCM", Stack "P"]
+      it "parses a single line of stacks" $ do
+        let row = head . lines $ inputStacks
+        parseRow row  `shouldBe` S.fromList [Stack "", Stack "D"]
+      it "combines stacks" $ do
+        (Stack "AB" <> Stack "CD") `shouldBe` Stack "ABCD"
+      it "combines rows" $ do
+        S.fromList [Stack "", Stack "A"] `combineRows` S.fromList [Stack "B", Stack "B"] `shouldBe` S.fromList [Stack "B", Stack "AB"]
+        S.empty `combineRows` S.fromList [Stack "B", Stack "B"] `shouldBe` S.fromList [Stack "B", Stack "B"]
+        S.fromList [Stack "A", Stack "B"] `combineRows` S.empty `shouldBe` S.fromList [Stack "A", Stack "B"]
+        S.singleton (Stack "") `combineRows` S.fromList[Stack "B", Stack "B"] `shouldBe` S.fromList [Stack "B", Stack "B"]
+        S.fromList [Stack "A", Stack "B"] `combineRows` S.singleton (Stack "") `shouldBe` S.fromList [Stack "A", Stack "B"]
+      it "splits input into stacks and operations" $ do
+        parseInput inputPart1 `shouldBe`
+         (S.fromList [Stack "NZ", Stack "DCM", Stack "P"],
+          [ Operation { count = 1, from = StackIndex 2, to = StackIndex 1},
+            Operation { count = 3, from = StackIndex 1, to = StackIndex 3},
+            Operation { count = 2, from = StackIndex 2, to = StackIndex 1},
+            Operation { count = 1, from = StackIndex 1, to = StackIndex 2}])
+      it "exeutes a count=1 operation on a row" $ do
+        let op = Operation { count = 1, from = StackIndex 2, to = StackIndex 3}
+        let row = S.fromList [Stack "NZ", Stack "DCM", Stack "P"]
+        executeOperation row op `shouldBe` S.fromList [Stack "NZ", Stack "CM", Stack "DP"]
+      it "exeutes a count > 1 operation on a row" $ do
+        let op = Operation { count = 2, from = StackIndex 2, to = StackIndex 3}
+        let row = S.fromList [Stack "NZ", Stack "DCM", Stack "P"]
+        executeOperation row op `shouldBe` S.fromList [Stack "NZ", Stack "M", Stack "CDP"]
+      it "finds the top items on stacks" $ do
+         let row = S.fromList [Stack "NZ", Stack "DCM", Stack "P"]
+         findTopOfStacks row `shouldBe` S.fromList "NDP"
+      it "solves the demo" $ do
+         day5_1 inputPart1 `shouldBe` "CMZ"
+    describe "Part1" $ do
+      it "executes 9001 operations on a row" $ do
+        let op = Operation { count = 2, from = StackIndex 2, to = StackIndex 3}
+        let row = S.fromList [Stack "NZ", Stack "DCM", Stack "P"]
+        execute9001Operation row op `shouldBe` S.fromList [Stack "NZ", Stack "M", Stack "DCP"]
+      it "solves the demo" $ do
+         day5_2 inputPart1 `shouldBe` "MCD"
+