3 files changed, 84 insertions(+), 0 deletions(-)

A 6/lex.mll
A 6/t1.ml
A 6/t2.ml

@@ 0,0 1,12 @@
+{
+type token =
+	| Chr of char
+	| Eof
+}
+
+rule token = parse
+	| ['a'-'z'] as c {
+		Chr c
+	}
+        | '\n' { Eof }
+	| eof { Eof }

@@ 0,0 1,36 @@
+open Lex
+
+type m = Found of int | Not of char list
+
+let rec f lexbuf =
+	match Lex.token lexbuf with
+	| Eof -> []
+	| Chr c -> c :: f lexbuf
+
+let solve m ((c, i): char * int) =
+	match m with
+	| Found _ -> m
+	| Not l ->
+			(match List.find_opt ((=) c) l with
+			| Some _ ->
+				let rec aux c = function
+					| [] -> invalid_arg "aux"
+					| e :: es when e = c -> []
+					| e :: es -> e :: aux c es
+				in
+				Not (c :: aux c l)
+			| None ->
+				if List.length l = 3 then
+					Found (i + 1)
+				else
+					Not (c :: l))
+
+let () =
+	stdin
+		|> Lexing.from_channel
+		|> f
+		|> List.mapi (fun i x -> (x, i))
+		|> List.fold_left solve (Not [])
+		|> (function Found i -> i | Not _ -> failwith "oops")
+		|> Printf.printf "%d\n"
+

@@ 0,0 1,36 @@
+open Lex
+
+type m = Found of int | Not of char list
+
+let rec f lexbuf =
+	match Lex.token lexbuf with
+	| Eof -> []
+	| Chr c -> c :: f lexbuf
+
+let solve m ((c, i): char * int) =
+	match m with
+	| Found _ -> m
+	| Not l ->
+			(match List.find_opt ((=) c) l with
+			| Some _ ->
+				let rec aux c = function
+					| [] -> invalid_arg "aux"
+					| e :: es when e = c -> []
+					| e :: es -> e :: aux c es
+				in
+				Not (c :: aux c l)
+			| None ->
+				if List.length l = 13 then
+					Found (i + 1)
+				else
+					Not (c :: l))
+
+let () =
+	stdin
+		|> Lexing.from_channel
+		|> f
+		|> List.mapi (fun i x -> (x, i))
+		|> List.fold_left solve (Not [])
+		|> (function Found i -> i | Not _ -> failwith "oops")
+		|> Printf.printf "%d\n"
+