day11

aoc2024/Day11.newt

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+module Day11
+
+import Prelude
+import Node
+import Aoc
+import SortedMap
+
+infixl 7 _%_
+pfunc _%_ : Int → Int → Int := `(x,y) => x % y`
+
+-- should have a few more foreign functions and do this in newt
+pfunc divide uses (_,_) : String → String × String := `(s) => {
+  let l = s.length/2|0
+  return _$2C_(undefined, undefined, s.slice(0,l), s.slice(l))
+}`
+
+step : List Int → List Int
+step = go Nil
+  where
+    go : List Int → List Int → List Int
+    go acc Nil = acc
+    go acc (0 :: xs) = go (1 :: acc) xs
+    go acc (x :: xs) =
+      let str = show x in
+      if slen str % 2 == 0
+        then let (a,b) = divide str in go (stringToInt a :: stringToInt b :: acc) xs
+        else go (2024 * x :: acc) xs
+
+foldMap : ∀ a b. {{Ord a}} {{Eq a}} → (b → b → b) → SortedMap a b → List (a × b) → SortedMap a b
+foldMap f m Nil = m
+foldMap f m ((a,b) :: xs) = case lookupMap a m of
+  Nothing => foldMap f (updateMap a b m) xs
+  Just (_, b') => foldMap f (updateMap a (f b' b) m) xs
+
+step2 : List (Int × Int) → List (Int × Int)
+step2 = go Nil
+  where
+    go : List (Int × Int) → List (Int × Int) → List (Int × Int)
+    go acc Nil = acc
+    go acc ((0,c) :: xs) = go ((1,c) :: acc) xs
+    go acc ((x,c) :: xs) =
+      let str = show x in
+      if slen str % 2 == 0
+        then let (a,b) = divide str in go ((stringToInt a,c) :: (stringToInt b,c) :: acc) xs
+        else go ((2024 * x,c) :: acc) xs
+
+iter : Int → SortedMap Int Int → Int
+iter count parts = let x = go count parts in foldl _+_ 0 $ map snd $ toList x
+  where
+    go : Int → SortedMap Int Int → SortedMap Int Int
+    go 0 stuff = stuff
+    go x stuff = go (x - 1) $ foldMap _+_ EmptyMap $ step2 $ toList stuff
+
+run : String -> IO Unit
+run fn = do
+  putStrLn fn
+  text <- readFile fn
+  let stuff = foldMap _+_ EmptyMap $ map (\ x => (stringToInt x, 1)) $ split (trim text) " "
+  let p1 = iter 25 stuff
+  putStrLn $ "part1 " ++ show p1
+  let p2 = iter 75 stuff
+  putStrLn $ "iter " ++ show p2
+
+main : IO Unit
+main = do
+  run "aoc2024/day11/eg.txt"
+  run "aoc2024/day11/input.txt"

aoc2024/day11/eg.txt

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+125 17