day 7 and 8

7/main.ml

@@ -0,0 +1,62 @@
+open Printf;;
+open String;;
+
+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 clean_string str =
+  str |> String.split_on_char ':' |> List.hd
+
+let rec parse_int_list sep str =
+  let list1 = (List.filter (fun a -> length a != 0) (String.split_on_char sep str)) in
+  List.map (fun x -> int_of_string @@ clean_string x) list1
+
+let rec is_possible_inner goal operand_list =
+  match operand_list with
+  | e1 :: tail1 -> begin
+    match tail1 with 
+    | e2 :: tail2 ->
+      is_possible_inner goal (e1 + e2 :: tail2)
+      || is_possible_inner goal (e1 * e2 :: tail2)
+    | _ -> goal == e1
+    end
+  | _ -> false
+
+let is_possible input_lst =
+  match input_lst with
+  | head :: tail -> is_possible_inner head tail
+  | _ -> false
+
+let rec int_concat a b =
+  int_of_string (String.cat (string_of_int a) (string_of_int b))
+
+let rec is_possible_extended_inner goal operand_list =
+  match operand_list with
+  | e1 :: tail1 -> begin
+    match tail1 with 
+    | e2 :: tail2 ->
+      is_possible_extended_inner goal (e1 + e2 :: tail2)
+      || is_possible_extended_inner goal (e1 * e2 :: tail2)
+      || is_possible_extended_inner goal (int_concat e1 e2 :: tail2)
+    | _ -> goal == e1
+    end
+  | _ -> false
+
+let is_possible_extended input_lst =
+  match input_lst with
+  | head :: tail -> is_possible_extended_inner head tail
+  | _ -> false
+
+let () =
+  let f = open_in "input.txt" in
+  let lines = List.map (fun a -> parse_int_list ' ' a) (list_of_lines f) in
+  let valid_lines = List.filter is_possible lines in
+  let valid_lines2 = List.filter is_possible_extended lines in
+  let result = List.fold_left (fun acc lst -> acc + List.hd lst) 0 valid_lines in
+  let result2 = List.fold_left (fun acc lst -> acc + List.hd lst) 0 valid_lines2 in
+  printf "%d\n%d\n" result result2