Day 2 part 2

ocaml/2.ml

@@ -3,47 +3,71 @@
 type shape = Rock | Paper | Scissors
 type outcome = Win | Tie | Loss
 
-let shape_of = function
+let shape_of_char = function
   | 'A' | 'X' -> Rock
   | 'B' | 'Y' -> Paper
   | 'C' | 'Z' -> Scissors
   | s -> failwith ("invalid shape: " ^ (String.make 1 s))
-;;
 
 let score_of_shape = function
   | Rock -> 1
   | Paper -> 2
   | Scissors -> 3
-;;
 
 let score_of_outcome = function
   | Loss -> 0
   | Tie -> 3
   | Win -> 6
-;;
 
-let outcome_of = function
-  | Rock, Scissors -> Win
-  | Paper, Rock -> Win
-  | Scissors, Paper -> Win
-  | a, b when a = b -> Tie
-  | _ -> Loss
-;;
-
-let play_round line =
-  let op_move = shape_of (String.get line 0) in
-  let my_move = shape_of (String.get line 2) in
-  let outcome = outcome_of(my_move, op_move) in
+let part1 line =
+  let outcome_of_round = function
+    | Rock, Scissors -> Win
+    | Paper, Rock -> Win
+    | Scissors, Paper -> Win
+    | a, b when a = b -> Tie
+    | _ -> Loss
+  in
+  let op_move = shape_of_char (String.get line 0) in
+  let my_move = shape_of_char (String.get line 2) in
+  let outcome = outcome_of_round(my_move, op_move) in
   let outcome_score = score_of_outcome outcome in
   let shape_score = score_of_shape my_move in
   outcome_score + shape_score
+
+let part2 line =
+  let outcome_of_char = function
+    | 'X' -> Loss
+    | 'Y' -> Tie
+    | 'Z' -> Win
+    | o -> failwith ("invalid outcome: " ^ (String.make 1 o))
+  in
+  let make_move = function
+    | Rock, Win -> Paper
+    | Rock, Loss -> Scissors
+    | Paper, Win -> Scissors
+    | Paper, Loss -> Rock
+    | Scissors, Win -> Rock
+    | Scissors, Loss -> Paper
+    | s, Tie -> s
+  in
+  let op_move = shape_of_char (String.get line 0) in
+  let outcome = outcome_of_char (String.get line 2) in
+  let my_move = make_move(op_move, outcome) in
+  let outcome_score = score_of_outcome outcome in
+  let shape_score = score_of_shape my_move in
+  outcome_score + shape_score
+
+let play lines part rules =
+  let score = lines
+    |> List.map rules
+    |> List.fold_left (+) 0
+  in
+  Printf.printf "Part %d: %d\n" part score
 ;;
 
 let contents = read_file "inputs/2.txt" in
-let score = String.split_on_char '\n' contents
+let lines = String.split_on_char '\n' contents
   |> List.filter (fun l -> String.trim l <> "")
-  |> List.map play_round
-  |> List.fold_left (+) 0
 in
-
-Printf.printf "%d" score
+play lines 1 part1;
+play lines 2 part2