2025 Day 6

Author: viandoxdev

2025/.gitignore

@@ -1 +1,2 @@
 _build
+inputs

2025/bin/main.ml

@@ -1,5 +1,7 @@
 open Aoc2025
 
-let () =
-  let aoc = Aoc.new_ctx () in
-  Aoc.run_days aoc
+let main () = 
+    let aoc = Aoc.new_ctx () in
+    Aoc.run_days aoc
+
+let () = main ()

2025/days/Day06.ml

@@ -1,6 +1,38 @@
 open Utils
 
+let parse input =
+    let (ops, numbers) = String.split_on_char '\n' input
+        |> List.rev 
+        |> function 
+            | [] -> failwith "bad input"
+            | x::xs -> x ^ " ", List.rev xs |> List.map (fun s -> s ^ " ")
+    in
+    let (s1, s2, _, _, _) = fold_range (fun (s1, s2, op, vers, hors) i -> 
+        let op = match op with 
+            | Some op -> Some op
+            | None -> (match ops.[i] with
+                | '*' -> Some (List.fold_left ( * ) 1)
+                | '+' -> Some (List.fold_left (+) 0)
+                | _ -> None) in
+        let n_vers = List.fold_left (fun a -> function
+            | '0'..'9' as c -> a * 10 + (int_of_char c - int_of_char '0')
+            | _ -> a) 0 (List.map (fun l -> l.[i]) numbers) in
+        let hors = List.map2 (fun a l -> match l.[i] with
+            | '0'..'9' as c -> a * 10 + (int_of_char c - int_of_char '0')
+            | _ -> a) hors numbers in
+        if List.for_all (fun l -> l.[i] = ' ') numbers then
+            let op = Option.get op in
+            (s1 + op hors, s2 + op vers, None, [], List.map (fun _ -> 0) numbers)
+        else
+            (s1, s2, op, n_vers :: vers, hors)
+
+    ) (0, 0, None, [], List.map (fun _ -> 0) numbers) 0 (String.length ops - 1)
+    in
+    s1, s2
+
 let day06 input =
-  ("TODO", "TODO")
+    let input = trim_end_nl input in
+    let part1, part2 = parse input in
+    (string_of_int part1, string_of_int part2)
 
 

2025/days/Utils.ml

@@ -70,3 +70,12 @@ let string_split_once pat s =
     let patlen, len = String.length pat, String.length s in
     let i = string_find_index pat s in
     (String.sub s 0 i, String.sub s (i + patlen) (len - i - patlen))
+
+let (<%) f g x = f (g x)
+let (%>) f g x = g (f x)
+
+let cons a l = a :: l
+
+let transpose = function
+    | [] -> []
+    | x::xs -> List.(fold_right (fun l a -> map2 cons l a) (x::xs) (map (fun _ -> []) x) )

2025/lib/Aoc.ml

@@ -49,7 +49,7 @@ let days =
     (3, Day03.day03);
     (4, Day04.day04);
     (5, Day05.day05);
-    (* (6, Day06.day06); *)
+    (6, Day06.day06);
     (* (7, Day07.day07); *)
     (* (8, Day08.day08); *)
     (* (9, Day09.day09); *)