Finsihed day 14

diff --git a/advent14/Main.hs b/advent14/Main.hs
index efd4db67d00a14345dcb2b4b58418bd4654e9584..1d0e71eb9313e5e7e3aaa1ab45911bcd90e467e3 100644 (file)
--- a/advent14/Main.hs
+++ b/advent14/Main.hs
@@ -1,4 +1,4 @@
--- Writeup at https://work.njae.me.uk/2023/12/15/advent-of-code-2023-day-13/
+-- Writeup at https://work.njae.me.uk/2023/12/18/advent-of-code-2023-day-14/
 
 import AoC
 import Data.List
@@ -17,33 +17,19 @@ main =
   do  dataFileName <- getDataFileName
       text <- readFile dataFileName
       let grid = transpose $ fmap (fmap readElem) $ lines text
-      -- print grid
-      -- print $ rollGrid $ transpose grid
-      -- let r1 = rollToCompletion grid
-      -- print r1
-      -- putStrLn $ showGrid r1
-      -- print $ transpose $ fmap reverse r1
+      -- print $ showGrid grid
       print $ part1 grid
-      -- print $ rollCycle grid
-      -- putStrLn $ showGrid $ rollCycle grid
-      -- putStrLn $ showGrid $ rollCycle $ rollCycle grid
-      -- putStrLn $ showGrid $ rollCycle $ rollCycle $ rollCycle grid
-      -- print $ findRepeat grid
-
-
-
       print $ part2 grid
-      -- print $ part2 patts
 
-part1 :: Grid -> Int
+part1, part2 :: Grid -> Int
 part1 grid = scoreGrid grid'
   where grid' = rollToCompletion grid
 
 part2 grid = scoreGrid finalGrid
-  where (grid', cache, i) = findRepeat grid
+  where (grid', cache, repeatEnd) = findRepeat grid
         repeatStart = cache M.! grid'
-        repeatLen = i - repeatStart
-        finalIndex = (1e9 - repeatStart - 1) `mod` repeatLen
+        repeatLen = repeatEnd - repeatStart
+        finalIndex = ((1e9 - repeatStart) `mod` repeatLen) + repeatStart
         (finalGrid, _) = M.findMin $ M.filter (== finalIndex) cache
 
 readElem :: Char -> Element
@@ -78,15 +64,13 @@ rotate1 = transpose . fmap reverse
 rollCycle :: Grid -> Grid
 rollCycle = appEndo (stimes 4 (Endo rotate1 <> Endo rollToCompletion))
 
+findRepeat :: Grid -> (Grid, Cache, Int)
+findRepeat grid = head $ dropWhile test $ iterate go (grid, M.empty, 0)
+  where test (g, c, _) = g `M.notMember` c
+        go (g, c, i) = (rollCycle g, M.insert g i c, (i + 1))
+
 showGrid :: Grid -> String
 showGrid grid = unlines $ fmap (fmap showElem) $ transpose grid
   where showElem Empty = '.'
         showElem Cube = '#'
         showElem Round = 'O'
-
-
-rollCycleWithCache (grid, cache, index) = (rollCycle grid, M.insert grid index cache, (index + 1))
-
-findRepeat grid = head $ dropWhile test $ iterate rollCycleWithCache (grid, M.empty, 0)
-  where test (g, c, i) = g `M.notMember` c
-