day 10

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

README

@@ -0,0 +1 @@
+My advent of code solutions for 2022. I am trying to not use String wherever possible and use Data.Text instead. That makes the programs appear bigger than they are LOC-wise.

day10.hs

@@ -0,0 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE ViewPatterns #-}
+
+import Data.Text (Text)
+import qualified Data.Text as T (lines, pack, unlines, words)
+import qualified Data.Text.IO as T (putStr)
+import qualified Data.Text.Read as T (decimal, signed)
+import Lib (readFile')
+
+main :: IO ()
+main = do
+  vals <-
+    scanl1 (+)
+      . reverse
+      . foldl
+        ( \xs x ->
+            let o : n = T.words x
+                dec (T.signed T.decimal . head -> Right (m, "")) = m
+             in if o == "noop" then 0 : xs else dec n : 0 : xs
+        )
+        [1]
+      . T.lines
+      <$> readFile' "day10.in"
+  putStr "Q1: "
+  print $ q1 vals
+  putStrLn "Q2: "
+  T.putStr $ q2 vals
+
+q1 :: [Int] -> Int
+q1 v = foldr (\x xs -> xs + (v !! (x - 1) * x)) 0 [20, 60 .. 220]
+
+q2 :: [Int] -> Text
+q2 v =
+  T.unlines $
+    map
+      ( \x ->
+          T.pack $
+            map (\y -> if abs (v !! (x + y) - y) <= 1 then '#' else '.') [0 .. 39]
+      )
+      [0, 40 .. 200]

day9.hs

@@ -33,7 +33,7 @@ moveTail (hx, hy) (tx, ty)
   | abs dx <= 1 && abs dy <= 1 = (tx, ty) -- dont move
   | abs dx > abs dy = (tx + signum dx, hy) -- move horizontally
   | abs dy > abs dx = (hx, ty + signum dy) -- move vertically
-  | otherwise = (tx + signum tx, ty + signum dy) -- move diagonally
+  | otherwise = (tx + signum dx, ty + signum dy ) -- move diagonally
   where
     dx = hx - tx
     dy = hy - ty