From 27e4f9102b90b208d537c4f36c3c5837130f2f7f Mon Sep 17 00:00:00 2001
From: pingu <nor@acorneroftheweb.com>
Date: Sun, 8 Dec 2024 14:45:24 +0100
Subject: [PATCH] Part 2 done

---
 app/8.hs | 33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/app/8.hs b/app/8.hs
index 2e08152..33ff476 100644
--- a/app/8.hs
+++ b/app/8.hs
@@ -1,11 +1,8 @@
-{-# LANGUAGE LambdaCase, MultiWayIf #-}
+{-# LANGUAGE MultiWayIf #-}
 module Main where
 
 import Data.Functor
 import Data.Matrix hiding (trace)
-import Data.List
-import Numeric.Extra
-import Debug.Trace
 
 data Pos = Pos { ch :: Char
                , ma :: Bool
@@ -29,9 +26,6 @@ getMarked s = zip [1..] (toLists s) >>= \(y,l) -> zip [1..] l >>= \(x,c) ->
 availableChars :: [Char]
 availableChars = ['a'..'z'] ++ ['A'..'Z'] ++ ['0'..'9']
 
-dist :: (Int,Int) -> (Int,Int) -> Float
-dist (y,x) (y',x') = sqrt $ intToFloat (y-y')^2 + intToFloat (x-x')^2
-
 line :: (Int,Int) -> (Int,Int) -> (Int,Int) -> Bool
 line (y1,x1) (y2,x2) (y3,x3) =
   if | x2 == x1 && x3 == x2 -> True
@@ -47,14 +41,20 @@ combo ps = [(a,b) | a <- ps, b <- ps, a /= b]
 getAntinodePos :: (Int,Int) -> [(Int,Int)] -> [(Int,Int)]
 getAntinodePos (i,j) ps =
   let inbounds (y,x) = and [0 < y, y <= i, 0 < x, x <= j] in
-    nub $ [ c | (p@(y,x),p'@(y',x')) <- combo ps,
+    [ c | (p@(y,x),p'@(y',x')) <- combo ps,
                  c <- [(y + (y-y'),x+(x-x')),
-                       (y - (y-y'),x+(x-x')),
-                       (y + (y-y'),x-(x-x')),
-                       (y - (y-y'),x-(x-x'))],
+                       (y - (y-y'),x+(x-x'))],
                  inbounds c,
                  line c p p']
 
+getAntinodePos' :: (Int,Int) -> [(Int,Int)] -> [(Int,Int)]
+getAntinodePos' (i,j) ps =
+  let inbounds (y,x) = and [0 < y, y <= i, 0 < x, x <= j]
+      a = combo ps >>= \((y,x),(y',x')) ->
+        takeWhile inbounds [ (y + step * (y - y'), x + step * (x - x')) | step <- [1..]]
+      b = combo ps >>= \((y,x),(y',x')) ->
+        takeWhile inbounds [ (y + step * (y - y'), x + step * (x - x')) | step <- [0,-1..]] in
+    a ++ b
 
 mark :: Matrix Pos -> [(Int,Int)] -> Matrix Pos
 mark = foldr (\p@(y,x) s -> let c = getElem y x s in setElem (c {ma = True}) p s)
@@ -63,10 +63,11 @@ solve1 :: Matrix Pos -> Int
 solve1 s = length . getMarked $
   foldr (flip mark . getAntinodePos (nrows s, ncols s) . (`positionsOfChar` s)) s availableChars
 
-solve2 = undefined
+solve2 :: Matrix Pos -> Int
+solve2 s = length . getMarked $
+  foldr (flip mark . getAntinodePos' (nrows s, ncols s) . (`positionsOfChar` s)) s availableChars
 
 main :: IO ()
-main = readFile "inputs/8.example" <&> parse >>= \i ->
-       print (solve1 i)
-       -- >>
-       -- print (solve2 i)
+main = readFile "inputs/8" <&> parse >>= \i ->
+       print (solve1 i) >>
+       print (solve2 i)