[Day 08] Done

1 files changed, 83 insertions, 0 deletions

diff --git a/day08/day08.hs b/day08/day08.hs
new file mode 100644
index 0000000..728dd71
--- /dev/null
+++ b/day08/day08.hs
@@ -0,0 +1,83 @@
+import Data.List
+
+type Vec = (Int, Int)
+type Ant = (Int, Int, Char)
+type Map = (Vec, [Ant])
+
+consume2 :: [Ant] -> Int -> Int -> [Char] -> [Ant]
+consume2 acc _ _ [] = acc
+consume2 acc r c ('.':t) = consume2 acc r (c+1) t
+consume2 acc r c (h:t) = consume2 ((r, c, h):acc) r (c+1) t
+
+consume1 :: [Ant] -> Int -> [[Char]] -> [Ant]
+consume1 acc _ [] = acc
+consume1 acc r (h:t) = consume1 (acc ++ (consume2 [] r 0 h)) (r+1) t
+
+consume :: [Char] -> Map
+consume file =
+  ((length grid, length $ head grid), consume1 [] 0 grid)
+  where grid = lines file
+
+neg :: Vec -> Vec
+neg (r, c) = (-r, -c)
+add :: Vec -> Vec -> Vec
+add (fr, fc) (dr, dc) = (fr + dr, fc + dc)
+scale :: Int -> Vec -> Vec
+scale m (r, c) = (r * m, c * m)
+path :: (Vec, Vec) -> Vec
+path (f, t) = add t $ neg f
+
+inside :: Vec -> Vec -> Bool
+inside (mr, mc) (r, c) =
+  r >= 0 && r < mr && c >= 0 && c < mc
+
+simplify :: Vec -> Vec
+simplify (r, c) =
+  (r `div` d, c `div` d)
+  where d = gcd r c
+
+antiNodes :: Map -> Char -> [Vec]
+antiNodes (size, ants) freq =
+  filter (inside size) $ map (\p@(f, _) -> add f $ scale 2 $ path p) pairs
+  where
+    fants = filter (\(_, _, f) -> f == freq) ants
+    coos = map (\(r, c, _) -> (r, c)) fants
+    pairs = [(a1, a2) | a1 <- coos, a2 <- coos, a1 /= a2]
+
+antiNodes22 :: [Vec] -> Vec -> Vec -> Vec -> [Vec]
+antiNodes22 acc size from del
+  | inside size nxt = antiNodes22 (nxt:acc) size nxt del
+  | otherwise = acc
+  where nxt = add from del
+
+antiNodes21 :: Vec -> (Vec, Vec) -> [Vec]
+antiNodes21 s p@(f, t) =
+  antiNodes22 [] s f d ++
+    [f] ++
+    antiNodes22 [] s f (neg d)
+  where
+    d = simplify $ path p
+
+antiNodes2 :: Map -> Char -> [Vec]
+antiNodes2 (size, ants) freq =
+  nub $ concat $ map (antiNodes21 size) pairs
+  where
+    fants = filter (\(_, _, f) -> f == freq) ants
+    coos = map (\(r, c, _) -> (r, c)) fants
+    pairs = [(a1, a2) | a1 <- coos, a2 <- coos, a1 /= a2]
+
+part1 mp@(_, ants) =
+  length $ nub $ concat $ map (antiNodes mp) freqs
+  where
+    freqs = nub $ map (\(_, _, f) -> f) ants
+
+part2 mp@(_, ants) =
+  length $ nub $ concat $ map (antiNodes2 mp) freqs
+  where
+    freqs = nub $ map (\(_, _, f) -> f) ants
+
+main = do
+  file <- readFile "day08.input"
+  let mp = consume file
+  putStrLn ("Part 1: " ++ (show $ part1 mp))
+  putStrLn ("Part 2: " ++ (show $ part2 mp))