From 15a856261b2c5baa25d5ea135aef710aff4bdc5b Mon Sep 17 00:00:00 2001
From: Jordan Doyle <jordan@doyle.la>
Date: Thu, 12 Dec 2024 23:25:09 +0000
Subject: [PATCH] Add 2024 day 10

---
 README     |  4 ++--
 2024/10.ml | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 76 insertions(+), 2 deletions(-)

diff --git a/README b/README
index edec381..5e855a0 100644
--- a/README
+++ a/README
@@ -23,8 +23,8 @@
 |        7 | Rust     | |        7 | Haskell  | +---------------------+
 |        8 | Rust     | |        8 | Haskell  |
 |        9 | OCaml    | |        9 | Haskell  |
-+---------------------+ |       10 | Haskell  |
-                        |       11 | Haskell  |
+|       10 | OCaml    | |       10 | Haskell  |
++---------------------+ |       11 | Haskell  |
                         |       12 | Rust     |
                         |       13 | Haskell  |
                         |       14 | Haskell  |
diff --git a/2024/10.ml b/2024/10.ml
new file mode 100755
index 0000000..aa8d4b4 100755
--- /dev/null
+++ a/2024/10.ml
@@ -1,0 +1,74 @@
+#!/usr/bin/env nix-shell
+
+(*
+#!nix-shell --pure -i ocaml -p ocaml
+*)
+
+let input =
+  let rec aux () =
+    try
+      let parsed_line =
+        read_line () |> String.to_seq
+        |> Seq.map (String.make 1)
+        |> Seq.map int_of_string |> List.of_seq
+      in
+      parsed_line :: aux ()
+    with End_of_file -> []
+  in
+  aux ()
+
+let input' = input |> List.map Array.of_list |> Array.of_list
+
+let is_valid (x, y) =
+  x >= 0 && y >= 0 && y < Array.length input' && x < Array.length input'.(0)
+
+let trailheads =
+  let rec aux x y = function
+    | [] ->
+        []
+    | [] :: rows ->
+        aux 0 (y + 1) rows
+    | (0 :: cols) :: rows ->
+        (x, y) :: aux (x + 1) y (cols :: rows)
+    | (_ :: cols) :: rows ->
+        aux (x + 1) y (cols :: rows)
+  in
+  aux 0 0 input
+
+module RatingMap = Map.Make (struct
+  type t = int * int
+
+  let compare = compare
+end)
+
+let ratings =
+  let rec find_paths curr (x, y) =
+    if curr = 9 then RatingMap.singleton (x, y) 1
+    else
+      let next = curr + 1 in
+      [(x, y - 1); (x, y + 1); (x - 1, y); (x + 1, y)]
+      |> List.filter is_valid
+      |> List.filter (fun (x, y) -> input'.(y).(x) = next)
+      |> List.map (find_paths next)
+      |> List.fold_left
+           (RatingMap.union (fun _ a b -> Some (a + b)))
+           RatingMap.empty
+  in
+  List.map (find_paths 0) trailheads
+
+let part1 =
+  List.fold_left (fun acc score -> acc + RatingMap.cardinal score) 0 ratings
+
+let _ = print_int part1
+
+let _ = print_newline ()
+
+let part2 =
+  List.fold_left
+    (fun acc score ->
+      acc + RatingMap.fold (fun _ value acc -> value + acc) score 0 )
+    0 ratings
+
+let _ = print_int part2
+
+let _ = print_newline ()
--
rgit 0.1.5