cache winner in Move

src/agent.rs

@@ -17,6 +17,7 @@ impl Agent for ManualAgent {
     fn next_move(&mut self, _: &Board) -> Option<(usize, usize)> {
         let stdin = io::stdin();
         let mut input = String::new();
+        println!("Your turn!");
         loop {
             input.clear();
             stdin.lock().read_line(&mut input).ok()?;

src/board.rs

@@ -201,17 +201,12 @@ impl Board {
     }
 
     pub fn game_winner(&self, turn: Piece) -> Option<Piece> {
-        let (white_score, black_score) = self.get_score();
-        let max_score = BOARD_SIZE * BOARD_SIZE;
-        let combined_score = black_score + white_score;
-        if max_score != combined_score {
+        if self.possible_moves(turn).count() > 0 {
+            // player can still make a move, there is no winner
             return None;
         }
 
-        // if current player cannot make a move
-        if self.possible_moves(turn).count() > 0 {
-            return None;
-        }
+        let (white_score, black_score) = self.get_score();
         match white_score.cmp(&black_score) {
             Ordering::Greater => Some(Piece::White), // White win
             Ordering::Less => Some(Piece::Black),    // Black win

src/complexagent.rs

@@ -13,6 +13,7 @@ struct Move {
     color: Piece,
     board: Board,
     next_move: Vec<Move>,
+    winner: Option<Piece>,
 }
 
 impl Move {
@@ -21,22 +22,28 @@ impl Move {
             return;
         }
 
-        if self.next_move.is_empty() {
-            self.next_move = problem_space(&self.board, !self.color).collect();
+        // only compute next move if this move doesn't end the game
+        if self.winner.is_none() {
+            if self.next_move.is_empty() {
+                self.next_move = problem_space(&self.board, !self.color).collect();
+            }
+            self.next_move
+                .iter_mut()
+                .for_each(|x| x.populate_next_moves(i - 1));
         }
-        self.next_move
-            .iter_mut()
-            .for_each(|x| x.populate_next_moves(i - 1));
     }
 
     fn value(&self, agent_color: Piece, depth: usize) -> i64 {
         let mut self_value = self.captured as i64;
 
-        if self.board.game_winner(agent_color) != Some(!agent_color) {
+        if self.winner == Some(!agent_color) {
             // if this board results in the opponent winning, MAJORLY negatively weigh this move
             // NOTE! this branch isn't completely deleted because if so, the bot wouldn't make a move.
             // We shouldn't prune branches because we still need to always react to the opponent's moves
             self_value = i64::MIN;
+        } else if self.winner == Some(agent_color) {
+            // this move results in a
+            self_value = i64::MAX;
         } else if agent_color != self.color {
             self_value = -self_value;
         }
@@ -81,7 +88,9 @@ impl Move {
                 color: !color,
                 board: *board,
                 next_move: problem_space(board, color).collect(),
+                winner: board.game_winner(!color),
             }],
+            winner: board.game_winner(color),
         }
     }
 }
@@ -100,6 +109,7 @@ fn problem_space(board: &Board, color: Piece) -> Box<dyn Iterator<Item = Move> +
                 color,
                 board,
                 next_move: Vec::new(),
+                winner: board.game_winner(color),
             }),
     )
 }

src/main.rs

@@ -10,8 +10,8 @@ mod piece;
 
 fn main() {
     let player1 = complexagent::ComplexAgent::new(Piece::Black);
-    let player2 = complexagent::ComplexAgent::new(Piece::White);
-    // let player2 = agent::ManualAgent::new(Piece::White);
+    // let player2 = complexagent::ComplexAgent::new(Piece::White);
+    let player2 = agent::ManualAgent::new(Piece::White);
     // let player2 = agent::RandomAgent::new(Piece::White);
     let mut game = Game::new(Box::new(player1), Box::new(player2));
     game.game_loop();