Tidyed up

[advent-of-code-21.git] / advent11 / Main.hs

diff --git a/advent11/Main.hs b/advent11/Main.hs
index a74f4fac33a81f31e480504a25484f9df020862d..3dd4975c8640185fcdef173ba1edb647f969d952 100644 (file)
--- a/advent11/Main.hs
+++ b/advent11/Main.hs
@@ -1,4 +1,4 @@
--- Writeup at https://work.njae.me.uk/2021/12/09/advent-of-code-2021-day-9/
+-- Writeup at https://work.njae.me.uk/2021/12/12/advent-of-code-2021-day-11/
 
 import Data.Array.IArray
 import Data.Char
@@ -24,8 +24,10 @@ mkGrid text = listArray ((V2 0 0), (V2 r c)) $ map mkOct $ concat rows
         c = (length $ head rows) - 1
         mkOct e = Octopus (digitToInt e) False
 
+part1 :: Grid -> Int
 part1 grid = snd $ (simulate grid) !! 100
 
+part2 :: Grid -> Int
 part2 grid = length $ takeWhile notSyncronised $ simulate grid
   where notSyncronised (g, _) = not $ simultaneous g
 
@@ -41,7 +43,7 @@ step (grid0, flashCount0) = (grid3, flashCount0 + numFlashers)
         numFlashers = length flashers
         grid3 = resetFlashers grid2 flashers
 
-
+simultaneous :: Grid -> Bool
 simultaneous grid = all zeroOct $ elems grid
   where zeroOct (Octopus 0 _) = True
         zeroOct _ = False
@@ -49,37 +51,39 @@ simultaneous grid = all zeroOct $ elems grid
 increment :: Grid -> Grid
 increment = amap incrementOne
 
+incrementSome :: Grid -> [Coord] -> Grid
 incrementSome grid locations = grid // (zip locations incrementedOcts)
   where incrementedOcts = map (incrementOne . (grid !)) locations
 
+incrementOne :: Octopus -> Octopus
 incrementOne (Octopus energy flashed) = Octopus (energy + 1) flashed 
 
-
 findFlashers :: Grid -> [Coord]
 findFlashers = map fst . filter (overpowered . snd) . assocs
   where overpowered (Octopus energy _) = energy > 9
 
-
+flash :: Grid -> [Coord] -> Grid
 flash grid [] = grid
 flash grid (here:agenda) 
+  -- already flashed, so ignore
   | flashed == True = flash grid agenda
+  -- not enough energy to flash, so ignore
   | energy <= 9 = flash grid agenda
   | otherwise = flash grid'' agenda'
-    -- set this as flashed
-    -- increment neighbours
-    -- add negighbours to agenda
   where Octopus energy flashed = grid ! here
         nbrs = neighbours grid here
-        octopus' = Octopus (energy + 1) True
-        agenda' = nbrs ++ agenda
+        -- set this as flashed
+        octopus' = Octopus energy True
         grid' = grid // [(here, octopus')]
+        -- add negighbours to agenda
+        agenda' = nbrs ++ agenda
+        -- increment neighbours
         grid'' = incrementSome grid' nbrs
 
 resetFlashers :: Grid -> [Coord] -> Grid
 resetFlashers grid locations = grid // (zip locations resetOcts)
   where resetOcts = repeat (Octopus 0 False)
 
-
 neighbours :: Grid -> Coord -> [Coord]
 neighbours grid here = filter (inRange (bounds grid))  
   [ here ^+^ (V2 r c)