day 6

day6.ml

@@ -0,0 +1,42 @@
+module CS = Set.Make(Char)
+
+let set_of_string str =
+    let rec aux s i st =
+        if i < 0 then st
+        else aux s (i - 1) (CS.add s.[i] st) in
+    aux str ((String.length str) - 1) CS.empty
+
+let all_char_set = "abcdefghijklmnopqrstuvwxyz" |> set_of_string
+
+
+let read_lines name =
+    let ic = open_in name in
+    let try_read () =
+        try Some (input_line ic)
+        with End_of_file -> None in
+    let rec loop acc group =
+        match try_read () with
+        | Some "" -> loop (group :: acc) []
+        | Some s -> loop acc (s :: group)
+        | None -> close_in ic; (group :: acc) in
+    loop [] []
+
+
+let part1 filename =
+    read_lines filename
+    |> List.map (fun x -> x
+                          |> (String.concat "")
+                          |> set_of_string
+                          |> CS.cardinal)
+    |> List.fold_left (+) 0
+
+let part2 filename =
+    read_lines filename
+    |> List.map (fun x -> x
+                          |> List.map set_of_string
+                          |> List.fold_left CS.inter all_char_set
+                          |> CS.cardinal)
+    |> List.fold_left (+) 0
+
+let () = print_endline (string_of_int (part1 "day6.input"))
+let () = print_endline (string_of_int (part2 "day6.input"))

day6.test

@@ -0,0 +1,15 @@
+abc
+
+a
+b
+c
+
+ab
+ac
+
+a
+a
+a
+a
+
+b