day10

Makefile

@@ -1,4 +1,4 @@
-DAY = 9
+DAY = 10
 
 DIR = day$(DAY)
 

day10/main.hs

@@ -0,0 +1,64 @@
+import System.IO
+
+import Data.List.Split
+
+import Debug.Trace
+
+
+
+data Cycle = Noop | Addx1 | Addx2 Int deriving (Show)
+
+
+
+parseInstr :: String -> [Cycle]
+parseInstr ('n':_) = [Noop]
+parseInstr ('a':xs) = [Addx1,Addx2 dx]
+    where
+        dxs = last $ splitOn " " xs
+        dx  = read dxs :: Int
+
+parseAsm :: String -> [Cycle]
+parseAsm = concat . map parseInstr . lines
+
+
+
+
+computeX :: Int -> Cycle -> Int
+computeX x (Addx2 dx) = x + dx
+computeX x _ = x
+
+
+
+
+drawCRT :: [Bool] -> (Int, Int) -> [Bool]
+drawCRT crt (c,x) = sx ++ [draw] ++ (tail xs)
+    where
+        (sx,xs) = splitAt c crt
+        sprite = [x-1,x,x+1]
+        col = (c `mod` 40)
+        draw = elem col sprite
+
+printCRT :: [Bool] -> String
+printCRT = concat . map (++"\n") . chunksOf 40 . map crtchr
+    where
+        crtchr False = '.'
+        crtchr True  = '#'
+
+
+
+
+handler :: String -> String
+handler s = (show $ sum score) ++ "\n" ++
+            (printCRT crt) ++ "\n"
+    where
+        cycles = parseAsm s
+        xhs = scanl computeX 1 cycles
+        sigstr = zipWith (*) [1..] xhs
+        score = map ((0:sigstr) !!) [20,60..220]
+        crt = foldl drawCRT (replicate 240 False) (zip [0..239] xhs)
+
+main :: IO ()
+main = do
+    interact handler
+
+