1 files changed, 73 insertions, 0 deletions
diff --git a/day14/day14.hs b/day14/day14.hs
new file mode 100644
index 0000000..337fe68
--- /dev/null
+++ b/day14/day14.hs
@@ -0,0 +1,73 @@
+import Data.List
+import Data.List.Split
+
+type Vec = (Int, Int)
+type Robot = (Vec, Vec)
+
+size :: Vec
+size = (101, 103)
+
+mul :: Int -> Vec -> Vec
+mul s (x, y) = (s*x, s*y)
+add :: Vec -> Vec -> Vec
+add (x, y) (z, w) = (x+z, y+w)
+clamp :: Vec -> Vec -> Vec
+clamp m@(mx, my) v@(x, y)
+  | x < 0 = clamp m (x + mx, y)
+  | y < 0 = clamp m (x, y + my)
+  | x >= mx = clamp m (x - mx, y)
+  | y >= my = clamp m (x, y - my)
+  | otherwise = v
+
+consume1 :: String -> Robot
+consume1 str =
+  ((atoi px, atoi py), (atoi vx, atoi vy))
+  where
+    atoi = (read::String->Int)
+    ["p", px, py, "v", vx, vy] = splitOneOf "=, " str
+
+consume :: String -> [Robot]
+consume file =
+  map consume1 $ lines file
+
+step :: [Robot] -> [Robot]
+step robots =
+  map stepOne robots
+  where
+    stepOne (p, v) = (clamp size $ add p v, v)
+
+applyN :: Int -> (a -> a) -> a -> a
+applyN n f =
+  foldr (.) id (replicate n f)
+
+count :: Vec -> Vec -> [Robot] -> Int
+count tl br robots =
+  length $ filter (inside tl br) robots
+  where
+    inside (xs, ys) (xe, ye) ((x, y), _) =
+      x >= xs && x < xe && y >= ys && y < ye
+
+counts :: [Robot] -> (Int, Int, Int, Int)
+counts robots =
+  (count (0, 0)               (tx, ty) robots,
+   count ((tx + 1), 0)        (mx, ty) robots,
+   count (0, (ty + 1))        (tx, my) robots,
+   count ((tx + 1), (ty + 1)) (mx, my) robots)
+  where
+    (mx, my) = size
+    tx = (mx - 1) `div` 2
+    ty = (my - 1) `div` 2
+
+safety :: (Int, Int, Int, Int) -> Int
+safety (a, b, c, d) =
+  a * b * c * d
+
+part1 :: [Robot] -> Int
+part1 robots =
+  safety $ counts $ applyN 100 step robots
+
+main = do
+  file <- readFile "day14.input"
+  let robots = consume file
+  putStrLn ("Part 1: " ++ (show $ part1 robots))
+  --putStrLn ("Part 2: " ++ (show $ part2 robots))