Add day 11

Author: vekerdyb

day11/Day11Part1Part2.hs

@@ -0,0 +1,98 @@
+import Data.List
+import Data.Ix
+size = 10
+
+indexFromCoords :: (Int, Int) -> Int
+indexFromCoords (x, y) = (y * size + x)
+
+exists :: (Int, Int) -> Bool
+exists (x, y) = x < size && x > -1 && y < size && y > -1
+
+octopus :: [Int] -> (Int, Int) -> Int
+octopus octopuses (x, y)
+    | exists (x, y) = octopuses!!(indexFromCoords (x, y))
+    | otherwise = -1
+
+set :: [Int] -> (Int, Int) -> Int -> [Int]
+set octopuses coords value  = (take $ indexFromCoords coords) octopuses
+                               ++ value:(drop (indexFromCoords coords + 1) octopuses)
+
+neighbours :: [Int] -> (Int, Int) -> [Int]
+neighbours octopuses (x, y) = map (octopus octopuses) (neighbourCoords (x, y))
+
+neighbourCoords :: (Int, Int) -> [(Int, Int)]
+neighbourCoords (x, y) = filter (\(x_, y_) -> exists (x_, y_)) [
+        (x', y') |
+        (x', y') <- range ((x - 1, y - 1), (x + 1, y + 1))
+        , not (x' == x && y' == y)
+    ]
+
+allCoords :: [(Int, Int)]
+allCoords = [(x, y) | (y, x) <- range((0,0), (size - 1,size - 1))]
+
+increaseBy1 ::  [Int] -> (Int, Int)  -> [Int]
+increaseBy1 octopuses coords  = (take $ indexFromCoords coords) octopuses
+                               ++ (octopus octopuses coords + 1):(drop (indexFromCoords coords + 1) octopuses)
+
+increaseAllBy1 :: [Int] -> [Int]
+increaseAllBy1 octopuses = map (+1) octopuses
+
+--maybeFlash :: [Int] -> [(Int, Int)] -> (Int, Int) -> [Int]
+--maybeFlash octopuses alreadyFlashed coords
+--    | coords `elem` alreadyFlashed = octopuses
+--    | octopus octopuses coords > 9 = neighbourCoords octopuses coords
+
+flashers :: [Int] -> [(Int, Int)]
+flashers octopuses = [coords | coords <- allCoords, octopus octopuses coords > 9 ]
+
+increaseNeighbours :: [Int] -> (Int, Int) -> [Int]
+increaseNeighbours octopuses coords = [
+        if (x, y) `elem` neighbourCoords coords
+            then (octopus octopuses (x, y) + 1)
+            else (octopus octopuses (x, y)) |
+            (x, y) <- allCoords
+    ]
+
+flashingStep :: [Int] -> [(Int, Int)] -> [(Int, Int)] -> [Int]
+flashingStep octopuses alreadyFlashed willFlash
+    | willFlash == [] = map (\x -> if x > 9 then 0 else x) octopuses
+    | otherwise = flashingStep (increasedNeighbours) (firstCoord:alreadyFlashed) newWillFlash
+    where firstCoord:coords = willFlash
+          increasedNeighbours = increaseNeighbours octopuses firstCoord
+          newWillFlash = [
+                    c | c <- flashers increasedNeighbours
+                    , c `notElem` willFlash
+                    , c `notElem` alreadyFlashed
+                ] ++ coords
+
+stepN :: [Int] -> Int -> [Int]
+stepN octopuses 0 = octopuses
+stepN octopuses n = stepN (flashingStep (increaseAllBy1 octopuses) [] (flashers (increaseAllBy1 octopuses))) (n - 1)
+
+countFlashesInNSteps :: [Int] -> Int -> Int -> Int
+countFlashesInNSteps octopuses flashesSoFar n
+    | n == 0 = flashesSoFar
+    | otherwise = countFlashesInNSteps steppedOctopuses (flashesSoFar + (length $ filter (==0) steppedOctopuses)) (n - 1)
+    where steppedOctopuses = flashingStep (increaseAllBy1 octopuses) [] (flashers $ increaseAllBy1 octopuses)
+
+findFirstSync :: [Int] -> Int -> Int
+findFirstSync octopuses steps
+    | sum octopuses == 0 = steps
+    | otherwise = findFirstSync (stepN octopuses 1) steps + 1
+
+-- helpers for debugging
+
+chunk :: Int -> [a] -> [[a]]
+chunk _ [] = []
+chunk n l
+  | n > 0 = (take n l) : (chunk n (drop n l))
+  | otherwise = error "Negative or zero n"
+
+printOctopuses :: [Int] -> IO ()
+printOctopuses octopuses = mapM_ putStrLn [ concat $ (intersperse " " [show o | o <- row ]) | row <- chunk size octopuses]
+
+main = do
+    contents <- readFile "day11/input.txt"
+    let octopuses = concat $ [[read (item:"")::Int | item <- row] | row <- lines contents]
+    putStrLn $ "Part 1: " ++ show (countFlashesInNSteps octopuses 0 100)
+    putStrLn $ "Part 2: " ++ show (findFirstSync octopuses 0)

day11/input.txt

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+4525436417
+1851242553
+5421435521
+8431325447
+4517438332
+3521262111
+3331541734
+4351836641
+2753881442
+7717616863

day11/sample.txt

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+5483143223
+2745854711
+5264556173
+6141336146
+6357385478
+4167524645
+2176841721
+6882881134
+4846848554
+5283751526