day7

aoc2024/Day7.newt

@@ -0,0 +1,58 @@
+module Day7
+
+import Prelude
+import Node
+import Aoc
+
+Prob : U
+Prob = Int × List Int
+
+cases : Int → Int → List Int → Bool
+cases goal acc Nil = goal == acc
+cases goal acc (x :: xs) =
+  if goal < acc then False
+  else if cases goal (x + acc) xs then True
+  else cases goal (x * acc) xs
+
+part1 : Prob → Bool
+part1 (goal, x :: xs) = cases goal x xs
+part1 _ = False
+
+cat : Int → Int → Int
+cat x y = stringToInt $ show x ++ show y
+
+cases2 : Int → Int → List Int → Bool
+cases2 goal acc Nil = goal == acc
+cases2 goal acc (x :: xs) =
+  if goal < acc then False
+  else if cases2 goal (x + acc) xs then True
+  else if cases2 goal (x * acc) xs then True
+  else cases2 goal (cat acc x) xs
+
+part2 : Prob → Bool
+part2 (goal, x :: xs) = cases2 goal x xs
+part2 _ = False
+
+parse : String -> Maybe (List Prob)
+parse text = do
+  traverse parseLine $ split (trim text) "\n"
+  where
+    parseLine : String → Maybe Prob
+    parseLine line = do
+      let (a :: b :: Nil) = split line ": " | _ => Nothing
+      Just (stringToInt a , nums b)
+
+run : String -> IO Unit
+run fn = do
+  putStrLn fn
+  text <- readFile fn
+  let (Just probs) = parse text | _ => putStrLn "parse error"
+  let p1 = foldl _+_ 0 $ map fst $ filter part1 probs
+  putStrLn $ "part1 " ++ show p1
+  let p2 = foldl _+_ 0 $ map fst $ filter part2 probs
+  putStrLn $ "part2 " ++ show p2
+
+main : IO Unit
+main = do
+  run "aoc2024/day7/eg.txt"
+  run "aoc2024/day7/input.txt"

aoc2024/day7/eg.txt

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+190: 10 19
+3267: 81 40 27
+83: 17 5
+156: 15 6
+7290: 6 8 6 15
+161011: 16 10 13
+192: 17 8 14
+21037: 9 7 18 13
+292: 11 6 16 20