From 414cb602af04f756ff2d582ef7494501a9a453b8 Mon Sep 17 00:00:00 2001
From: Quinten Kock <quintenkock@gmail.com>
Date: Mon, 13 Dec 2021 07:02:19 +0100
Subject: [PATCH] day13: speed up with hashset and dead code removal

---
 2021/day13.hs | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/2021/day13.hs b/2021/day13.hs
index 04ed14d..13959a7 100644
--- a/2021/day13.hs
+++ b/2021/day13.hs
@@ -1,6 +1,7 @@
 module Day13 where
 import Data.List.Split (splitOn)
 import Data.List (nub, sort)
+import qualified Data.HashSet as S
 import Debug.Trace (trace)
 
 type Dot = (Int,Int)
@@ -20,23 +21,21 @@ main :: IO ()
 main = do
     input <- lines <$> getContents
     let [dots',folds'] = splitOn [""] input
-    let dots = nub $ map parse dots'
+    let dots = map parse dots'
     let folds = map parseFold folds'
 
     putStr "part 1: "
-    let dots1 = nub $ sort $ map (fold (head folds)) dots
-    print $ length dots1
+    let dots1 = S.fromList $ map (fold (head folds)) dots
+    print $ S.size dots1
 
-    putStr "part 2: "
-    let dots2 = nub $ sort $ map (\d -> foldl (flip fold) d folds) dots
-    print dots2
+    putStrLn "part 2: "
+    let dots2 = map (\d -> foldl (flip fold) d folds) dots
+    let dots2' = S.fromList dots2
     let min_x = minimum $ map fst dots2
     let max_x = maximum $ map fst dots2
     let min_y = minimum $ map snd dots2
     let max_y = maximum $ map snd dots2
     mapM_ (\y -> do
-            mapM_ (\x -> putChar (if (x,y) `elem` dots2 then '#' else '.')) [0..max_x]
+            mapM_ (\x -> putChar (if (x,y) `S.member` dots2' then '#' else '.')) [0..max_x]
             putStrLn ""
         ) [0..max_y]
-    -- print dots2
-    -- print $ length dots2