Day 14, Part 1

Day14/puzzle1.hs

@@ -0,0 +1,41 @@
+import Data.Char (isDigit)
+import Data.List.Split (splitOn)
+
+type Position = (Int, Int)
+type Velocity = (Int, Int)
+type Robot = (Position, Velocity)
+
+readRobot :: String -> Robot
+readRobot s = let [ps, vs] = splitOn " " s
+                  [px, py] = map read . splitOn "," $ filter (\x -> isDigit x || x == ',' || x == '-') ps
+                  [vx, vy] = map read . splitOn "," $ filter (\x -> isDigit x || x == ',' || x == '-') vs
+              in  ((px, py), (vx, vy))
+
+moveRobot :: Int -> Robot -> Robot
+moveRobot 0 r = r
+moveRobot n r = let (px, py) = fst r
+                    (vx, vy) = snd r
+                in  moveRobot (n - 1) (((px + vx) `mod` 101, (py + vy) `mod` 103), (vx, vy))
+
+quadrant :: Robot -> Int
+quadrant r
+    | fst p `elem` [0..49] &&
+        snd p `elem` [0..50] = 0
+    | fst p `elem` [51..100] &&
+        snd p `elem` [0..50] = 1
+    | fst p `elem` [0..49] &&
+        snd p `elem` [52..102] = 2
+    | fst p `elem` [51..100] &&
+        snd p `elem` [52..102] = 3
+    | otherwise = -1
+    where p = fst r
+
+main = do
+    contents <- lines <$> readFile "day14.txt"
+    let robots =  map readRobot contents
+        robots' = map (moveRobot 100) robots
+        firstQ = length $ filter (\r -> quadrant r == 0) robots'
+        secondQ = length $ filter (\r -> quadrant r == 1) robots'
+        thirdQ = length $ filter (\r -> quadrant r == 2) robots'
+        fourthQ = length $ filter (\r -> quadrant r == 3) robots'
+    print $ firstQ * secondQ * thirdQ * fourthQ