finish day8 and refactor

aoc2024.cabal

@@ -27,6 +27,7 @@ library
   exposed-modules:
       Data.List.Extra
       Data.Matrix
+      Data.Point
       Day1
       Day2
       Day3

src/Data/Matrix.hs

@@ -3,7 +3,6 @@
 
 module Data.Matrix
   ( Matrix,
-    Position,
     buildMatrix,
     lookupValue,
     lookup,
@@ -21,12 +20,11 @@ import Data.List (find)
 import Data.Map.Lazy (Map)
 import qualified Data.Map.Lazy as Map
 import Data.Maybe
+import Data.Point (Point)
 import Prelude hiding (filter, lookup)
 
 newtype Matrix v = Matrix (Map (Int, Int) v)
 
-type Position = (Int, Int)
-
 buildMatrix :: [[a]] -> Matrix a
 buildMatrix xs = Matrix (go xs 0 Map.empty)
   where
@@ -43,22 +41,22 @@ buildMatrix xs = Matrix (go xs 0 Map.empty)
 size :: Matrix v -> Int
 size (Matrix hmap) = Map.size hmap
 
-isInBounds :: Position -> Matrix v -> Bool
+isInBounds :: Point -> Matrix v -> Bool
 isInBounds pos (Matrix hmap) = Map.member pos hmap
 
-filterWithKey :: (Position -> v -> Bool) -> Matrix v -> Matrix v
+filterWithKey :: (Point -> v -> Bool) -> Matrix v -> Matrix v
 filterWithKey f (Matrix hmap) = Matrix (Map.filterWithKey f hmap)
 
 filter :: (v -> Bool) -> Matrix v -> Matrix v
 filter f (Matrix hmap) = Matrix (Map.filter f hmap)
 
-lookup :: Position -> Matrix v -> Maybe v
+lookup :: Point -> Matrix v -> Maybe v
 lookup position (Matrix hmap) = Map.lookup position hmap
 
-lookupMultiple :: [Position] -> Matrix v -> [v]
+lookupMultiple :: [Point] -> Matrix v -> [v]
 lookupMultiple positions matrix = mapMaybe (`lookup` matrix) positions
 
-insert :: Position -> v -> Matrix v -> Matrix v
+insert :: Point -> v -> Matrix v -> Matrix v
 insert position value (Matrix hmap) =
   Matrix $
     if Map.member position hmap
@@ -69,7 +67,7 @@ insert position value (Matrix hmap) =
   Search for the given value on the matrix.
   Return the position of the first match if found and nothing if it doens't exist.
 --}
-lookupValue :: (Eq v) => v -> Matrix v -> Maybe Position
+lookupValue :: (Eq v) => v -> Matrix v -> Maybe Point
 lookupValue v (Matrix hmap) =
   let entries = Map.toAscList hmap
       mEntry = find ((== v) . snd) entries
@@ -80,7 +78,7 @@ Group elements given a function.
 The function receives an entry of the matrix and returns a pair of key -> value.
 The values are grouped in order.
 --}
-groupByWith :: forall v a b. (Ord a) => ((Position, v) -> (a, b)) -> Matrix v -> Map a [b]
+groupByWith :: forall v a b. (Ord a) => ((Point, v) -> (a, b)) -> Matrix v -> Map a [b]
 groupByWith f (Matrix hmap) =
   let sortedEntries = Map.toAscList hmap
    in foldr (insert' . f) Map.empty sortedEntries

src/Data/Point.hs

@@ -0,0 +1,18 @@
+module Data.Point
+  ( Point,
+    substract,
+    add,
+    distance,
+  )
+where
+
+type Point = (Int, Int)
+
+substract :: Point -> (Int, Int) -> (Int, Int)
+substract (x, y) (dx, dy) = (x - dx, y - dy)
+
+add :: Point -> (Int, Int) -> (Int, Int)
+add (x, y) (dx, dy) = (x + dx, y + dy)
+
+distance :: Point -> Point -> (Int, Int)
+distance (xrow, xcol) (yrow, ycol) = (xrow - yrow, xcol - ycol)

src/Day6.hs

@@ -1,8 +1,9 @@
 module Day6 (partOne, partTwo) where
 
 import qualified Data.HashSet as HashSet
-import Data.Matrix (Matrix, Position)
+import Data.Matrix (Matrix)
 import qualified Data.Matrix as M
+import Data.Point (Point)
 import Day6.Guard (Guard (..))
 import qualified Day6.Guard as G
 
@@ -21,8 +22,8 @@ partTwo input = do
   let labMap = parseLabMap input
   guard <- findGuard labMap
   route <- predictGuardsRoute guard labMap
-  let initialPosition = position guard
-      candidates = filter (/= initialPosition) route
+  let initialPoint = position guard
+      candidates = filter (/= initialPoint) route
 
   return $
     length $
@@ -52,7 +53,7 @@ findGuard matrix =
         [_, _, _, Just pos] -> Right (Guard pos G.Left)
         _ -> Left GuardNotFoundError
 
-predictGuardsRoute :: Guard -> LabMap -> Either Error [Position]
+predictGuardsRoute :: Guard -> LabMap -> Either Error [Point]
 predictGuardsRoute initialGuard labMap = go initialGuard HashSet.empty HashSet.empty
   where
     go guard visited acc =

src/Day6/Guard.hs

@@ -3,7 +3,7 @@
 module Day6.Guard (Guard (..), Direction (..), moveForward, turnRight) where
 
 import Data.Hashable
-import Data.Matrix (Position)
+import Data.Point (Point)
 import GHC.Generics (Generic)
 import Prelude hiding (Left, Right)
 
@@ -12,7 +12,7 @@ data Direction = Up | Down | Left | Right
 
 instance Hashable Direction
 
-data Guard = Guard {position :: Position, directon :: Direction}
+data Guard = Guard {position :: Point, directon :: Direction}
   deriving (Eq, Generic)
 
 instance Hashable Guard

src/Day8.hs

@@ -1,51 +1,45 @@
 module Day8 (partOne, partTwo) where
 
 import Data.List (nub)
-import Data.List.Extra (pairs)
+import qualified Data.List.Extra as LE
 import qualified Data.Map.Lazy as Map
-import Data.Matrix (Matrix, Position)
+import Data.Matrix (Matrix)
 import qualified Data.Matrix as M
-
-type Node = (Int, Int)
+import Data.Point (Point)
+import qualified Data.Point as P
 
 partOne :: String -> Int
-partOne input = length $ filter (`M.isInBounds` grid) $ nub antiNodes
-  where
-    grid = M.buildMatrix (lines input)
-    antiNodes = concatMap (uncurry getAntiNodes) $ nodePairs grid
-
-    getAntiNodes x y = case distance x y of
-      (0, 0) -> []
-      d -> [add x d, substract y d]
-
-partTwo :: String -> Int
-partTwo input = length antiNodes
+partOne input = length $ filter (`M.isInBounds` matrix) $ nub antiNodes
   where
     matrix = M.buildMatrix (lines input)
-    combinations = nodePairs matrix
-    antiNodes = nub $ concatMap (uncurry getAntiNodes) combinations
+    pairs = pairNodes matrix
+    antiNodes = concatMap (uncurry getAntiNodes) pairs
 
-    getAntiNodes x y = case distance x y of
-      (0, 0) -> []
-      d -> computePointsAtDistance x d add ++ computePointsAtDistance y d substract
+    getAntiNodes x y =
+      case P.distance x y of
+        (0, 0) -> []
+        d -> [P.add x d, P.substract y d]
 
-    computePointsAtDistance point dist f =
-      let point' = f point dist
-       in if M.isInBounds point matrix
-            then point : computePointsAtDistance point' dist f
-            else []
+partTwo :: String -> Int
+partTwo input = length (nub antiNodes)
+  where
+    matrix = M.buildMatrix (lines input)
+    pairs = pairNodes matrix
+    antiNodes = concatMap (uncurry getAntiNodes) pairs
 
-nodePairs :: Matrix Char -> [(Node, Node)]
-nodePairs matrix =
+    getAntiNodes x y =
+      let distance = P.distance x y
+       in go x distance P.add ++ go y distance P.substract
+      where
+        go _ (0, 0) _ = []
+        go point distance f =
+          let point' = f point distance
+           in if M.isInBounds point matrix
+                then point : go point' distance f
+                else []
+
+pairNodes :: Matrix Char -> [(Point, Point)]
+pairNodes matrix =
   let noDotsMatrix = M.filter (/= '.') matrix
       pointGroups = Map.elems $ M.groupByWith (\(position, value) -> (value, position)) noDotsMatrix
-   in concatMap pairs pointGroups
-
-substract :: Position -> (Int, Int) -> (Int, Int)
-substract (x, y) (dx, dy) = (x - dx, y - dy)
-
-add :: Position -> (Int, Int) -> (Int, Int)
-add (x, y) (dx, dy) = (x + dx, y + dy)
-
-distance :: Position -> Position -> (Int, Int)
-distance (xrow, xcol) (yrow, ycol) = (xrow - yrow, xcol - ycol)
+   in concatMap LE.pairs pointGroups