diff --git a/10/main.ml b/10/main.ml
new file mode 100644
index 0000000..290cf81
--- /dev/null
+++ b/10/main.ml
@@ -0,0 +1,90 @@
+open Printf;;
+open String;;
+open Map;;
+
+let rec list_of_lines in_file =
+  try
+    let line = input_line in_file in
+    line :: list_of_lines(in_file)
+  with End_of_file ->
+    close_in in_file;
+    []
+
+let file_to_2d_array in_file =
+  let lines = list_of_lines in_file in
+  let size_x = length @@ List.hd lines in
+  let size_y = List.length lines in
+  let arr = Array.make_matrix size_x size_y '?' in
+  List.iteri (fun j line -> String.iteri (fun i c -> arr.(j).(i) <- c) line) lines;
+  arr
+
+let find_all_indices_of elem arr =
+  arr |> Array.to_seq
+      |> Seq.mapi (fun i x -> (i, x))
+      |> Seq.filter_map (fun (i, x) -> if x = elem then Some i else None)
+
+let find_all_indices_of_2d elem arr =
+  arr |> Array.to_seq
+      |> Seq.mapi (fun j row -> Seq.map (fun i -> (i, j)) (find_all_indices_of elem row))
+      |> Seq.concat
+
+let rec try_walk_to (x, y) expected_value arr visited =
+  try
+    if visited.(y).(x) then
+      0
+    else if int_of_char arr.(y).(x) <> expected_value then
+      0
+    else
+      walk_and_count_trails (x, y) arr visited
+  with Invalid_argument _ -> 0
+
+and walk_and_count_trails (x, y) arr visited =
+  visited.(y).(x) <- true;
+  let elevation = int_of_char arr.(y).(x) in
+  if elevation = int_of_char '9' then
+    1
+  else
+    let next_elevation = elevation + 1 in
+    try_walk_to (x - 1, y) next_elevation arr visited
+    + try_walk_to (x + 1, y) next_elevation arr visited
+    + try_walk_to (x, y - 1) next_elevation arr visited
+    + try_walk_to (x, y + 1) next_elevation arr visited
+
+let rec try_walk_to_no_checking (x, y) expected_value arr =
+  try
+    if int_of_char arr.(y).(x) <> expected_value then
+      0
+    else
+      walk_and_count_trails_no_checking (x, y) arr
+  with Invalid_argument _ -> 0
+
+and walk_and_count_trails_no_checking (x, y) arr =
+  let elevation = int_of_char arr.(y).(x) in
+  if elevation = int_of_char '9' then
+    1
+  else
+    let next_elevation = elevation + 1 in
+    try_walk_to_no_checking (x - 1, y) next_elevation arr
+    + try_walk_to_no_checking (x + 1, y) next_elevation arr
+    + try_walk_to_no_checking (x, y - 1) next_elevation arr
+    + try_walk_to_no_checking (x, y + 1) next_elevation arr
+
+let get_trailhead_score arr pos = 
+  let visited = Array.make_matrix (Array.length arr.(0)) (Array.length arr) false in
+  walk_and_count_trails pos arr visited
+
+let get_trailhead_rating arr pos = 
+  walk_and_count_trails_no_checking pos arr
+
+let () =
+  let f = open_in "input.txt" in
+  let arr = file_to_2d_array f in
+  let trailheads = find_all_indices_of_2d '0' arr |> List.of_seq in
+  let result = trailheads
+    |> List.map (get_trailhead_score arr) 
+    |> List.fold_left Int.add 0 in
+  let result2 = trailheads
+    |> List.map (get_trailhead_rating arr) 
+    |> List.fold_left Int.add 0 in
+  printf "%d\n" result;
+  printf "%d\n" result2;
\ No newline at end of file