refactoring in playground, use zip file for web

playground/samples/aoc2023/Day3.newt

@@ -0,0 +1,115 @@
+module Day3
+
+import Prelude
+import Node
+
+pfunc repr : {a : U} -> a -> String := `(a,o) => ''+o`
+pfunc jrepr : {a : U} -> a -> String := `(a,o) => JSON.stringify(o, null, '  ')`
+
+
+maybe : ∀ a b. b → (a → b) → Maybe a → b
+maybe def f Nothing = def
+maybe def f (Just a) = f a
+
+-- was 'structure' I could make a `record` that destructures to this..
+data Number : U where
+  MkNumber : (start : Nat) -> (stop : Nat) → (value : Int) → Number
+
+isDigit : Char -> Bool
+isDigit '0' = True
+isDigit '1' = True
+isDigit '2' = True
+isDigit '3' = True
+isDigit '4' = True
+isDigit '5' = True
+isDigit '6' = True
+isDigit '7' = True
+isDigit '8' = True
+isDigit '9' = True
+isDigit _ = False
+
+numbers : List Char -> List Number
+numbers arr = go arr Z
+  where
+    go : List Char → Nat → List Number
+    go (c :: cs) start = if isDigit c
+      then case span isDigit (c :: cs) of
+          (front,back) => let stop = start + length front
+            in MkNumber start stop (stringToInt $ pack front) :: go back stop
+      else go cs (S start)
+    go Nil start = Nil
+
+
+range : ∀ a. Nat -> Nat -> List a -> List a
+range _ _ Nil = Nil
+range _ Z _ = Nil
+range Z (S k) (x :: xs) = x :: range Z k xs
+range (S n) (S m) (x :: xs) = range n m xs
+
+isPart : List (List Char) -> Nat -> Number -> Bool
+isPart rows row (MkNumber start end _) =
+  checkRow (pred row) || checkRow row || checkRow (S row)
+  where
+    isThing : Char -> Bool
+    isThing c = not (isDigit c || c == '.')
+
+    checkRow : Nat -> Bool
+    checkRow r = case getAt r rows of
+      Nothing => False
+      Just chars => case filter isThing (range (pred start) (S end) chars) of
+        Nil => False
+        _ => True
+
+getValue : Number -> Int
+getValue (MkNumber _ _ v) = v
+
+part1 : List (List Char) -> Int
+part1 rows =
+    foldl (\ acc num => acc + getValue num) 0 $
+      join $ map (partNums rows) $ enumerate rows
+  where
+    partNums : List (List Char) -> (Nat × List Char) -> List Number
+    partNums grid (r, cs) =
+      filter (isPart grid r) $ (numbers cs)
+
+gears : List (List Char) -> List Char -> Nat -> Int
+gears rows row y =
+    let a = numbers (getAt! (pred y) rows)
+        b = numbers (getAt! y rows)
+        c = numbers (getAt! (S y) rows)
+        all = a ++ b ++ c
+        cands = map fst $ filter (_==_ '*' ∘ snd) (enumerate row)
+    in foldl _+_ 0 $ map (check all) cands
+  where
+    ratio : List Int → Int
+    ratio (a :: b :: Nil) = a * b
+    ratio _ = 0
+
+    match : Nat → Number → Bool
+    match y (MkNumber start stop value) = pred start <= y && y < S stop
+
+    check : List Number → Nat →  Int
+    check nums y = ratio $ map getValue (filter (match y) nums)
+
+part2 : List (List Char) -> Int
+part2 rows =
+  foldl go 0 (enumerate rows)
+  where
+    go : Int → Nat × List Char → Int
+    go acc (y, row) = acc + gears rows row y
+
+-- 4361 / 467835
+-- 517021 / 81296995
+run : String -> IO Unit
+run fn = do
+  content <- readFile fn
+  let grid = (splitOn '\n' $ unpack $ trim content)
+  putStrLn fn
+  printLn (part1 grid)
+  printLn (part2 grid)
+
+main : IO Unit
+main = do
+  run "aoc2023/day3/eg.txt"
+  run "aoc2023/day3/input.txt"
+