4 files changed, 233 insertions(+), 0 deletions(-)

A 1.in
A 1.ml
A 1a.out
A 1b.out

@@ 0,0 1,200 @@
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@@ 0,0 1,31 @@
+let rec to_num_list chan : (int list) =
+	let num = try Some (int_of_string (input_line chan)) with End_of_file -> None in
+	if not (Option.is_none num) then
+		(Option.get num) :: (to_num_list chan)
+	else
+		[];;
+
+let read_from filename =
+	let in_chan = open_in filename in
+	let lst = to_num_list in_chan in
+	close_in in_chan;
+	lst;;
+
+let rec find_three filename lst back : int list =
+	match back with
+	| a :: b :: c :: [] ->
+			if a + b + c = 2020 then
+				let result = (max a 1) * b * (max c 1) in
+				let chan = open_out filename in
+				Printf.fprintf chan "%d\n" result;
+				close_out chan;
+				[0]
+			else
+				[0]
+	| back -> List.concat (List.map (fun a -> find_three filename lst (a::back)) lst)
+
+let lst = read_from "1.in";;
+
+find_three "1a.out" lst [0];;
+
+find_three "1b.out" lst [];;

@@ 0,0 1,1 @@
+719796

@@ 0,0 1,1 @@
+144554112