feat: Board 新增 Zobrist 哈希增量更新 + 3 测试

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

core/src/board.rs

@@ -1,4 +1,4 @@
-use crate::types::{CellState, Color, Move, MoveError, Position, MAX_BOARD_SIZE};
+use crate::types::{CellState, Color, Move, MoveError, Position, ZobristHash, MAX_BOARD_SIZE};
 
 /// 棋盘主体 — 不可变风格, place/undo 返回新 Board
 #[derive(Debug, Clone, PartialEq)]
@@ -7,6 +7,7 @@ pub struct Board {
     cells: [[CellState; MAX_BOARD_SIZE]; MAX_BOARD_SIZE],
     history: Vec<Move>,
     current_turn: u32,
+    pub zobrist_hash: ZobristHash,
 }
 
 impl Board {
@@ -22,6 +23,7 @@ impl Board {
             cells: [[CellState::Empty; MAX_BOARD_SIZE]; MAX_BOARD_SIZE],
             history: Vec::new(),
             current_turn: 0,
+            zobrist_hash: 0,
         }
     }
 
@@ -33,6 +35,11 @@ impl Board {
         self.cells[pos.x][pos.y]
     }
 
+    /// 获取当前局面 Zobrist 哈希
+    pub fn hash(&self) -> ZobristHash {
+        self.zobrist_hash
+    }
+
     /// 落子 — 返回新 Board (不可变)
     pub fn place(&self, pos: Position, color: Color) -> Result<Board, MoveError> {
         if pos.x >= self.size || pos.y >= self.size {
@@ -44,6 +51,9 @@ impl Board {
 
         let mut new_board = self.clone();
         new_board.cells[pos.x][pos.y] = CellState::Occupied(color);
+        let color_idx = if matches!(color, Color::Black) { 0 } else { 1 };
+        let zobrist = crate::types::init_zobrist_table(self.size);
+        new_board.zobrist_hash ^= zobrist[pos.x][pos.y][color_idx];
         new_board.history.push(Move {
             position: pos,
             color,
@@ -104,6 +114,14 @@ impl Board {
         let mut new_board = self.clone();
         let last_move = new_board.history.pop().unwrap();
         new_board.cells[last_move.position.x][last_move.position.y] = CellState::Empty;
+        let last_color_idx = if matches!(last_move.color, Color::Black) {
+            0
+        } else {
+            1
+        };
+        let zobrist = crate::types::init_zobrist_table(self.size);
+        new_board.zobrist_hash ^=
+            zobrist[last_move.position.x][last_move.position.y][last_color_idx];
         new_board.current_turn = self.current_turn.saturating_sub(1);
         Ok(new_board)
     }
@@ -269,4 +287,31 @@ mod tests {
         let _new = board.place(Position::new(7, 7), Color::Black).unwrap();
         assert_eq!(board.get(Position::new(7, 7)), CellState::Empty);
     }
+
+    #[test]
+    fn test_zobrist_hash_changes_on_place() {
+        let board = Board::new(15);
+        let h1 = board.hash();
+        let board2 = board.place(Position::new(7, 7), Color::Black).unwrap();
+        assert_ne!(h1, board2.hash());
+    }
+
+    #[test]
+    fn test_zobrist_hash_restores_on_undo() {
+        let board = Board::new(15);
+        let board = board.place(Position::new(7, 7), Color::Black).unwrap();
+        let h1 = board.hash();
+        let board = board.place(Position::new(7, 8), Color::White).unwrap();
+        assert_ne!(h1, board.hash());
+        let board = board.undo().unwrap();
+        assert_eq!(h1, board.hash());
+    }
+
+    #[test]
+    fn test_zobrist_hash_symmetry() {
+        let board = Board::new(15);
+        let b1 = board.place(Position::new(7, 7), Color::Black).unwrap();
+        let b2 = board.place(Position::new(7, 8), Color::Black).unwrap();
+        assert_ne!(b1.hash(), b2.hash());
+    }
 }

core/src/types.rs

@@ -152,3 +152,27 @@ impl Default for GameConfig {
         }
     }
 }
+
+/// Zobrist 哈希值
+pub type ZobristHash = u64;
+
+/// 获取全局 Zobrist 随机表（只初始化一次，使用 MAX_BOARD_SIZE 确保所有棋盘尺寸可用）
+pub fn init_zobrist_table(_board_size: usize) -> &'static Vec<Vec<[ZobristHash; 2]>> {
+    use std::collections::hash_map::RandomState;
+    use std::hash::BuildHasher;
+    use std::sync::OnceLock;
+    static TABLE: OnceLock<Vec<Vec<[ZobristHash; 2]>>> = OnceLock::new();
+    TABLE.get_or_init(|| {
+        let size = MAX_BOARD_SIZE;
+        let rng = RandomState::new();
+        let mut table = Vec::with_capacity(size);
+        for x in 0..size {
+            let mut row = Vec::with_capacity(size);
+            for _y in 0..size {
+                row.push([rng.hash_one(&(x, _y, 0u8)), rng.hash_one(&(x, _y, 1u8))]);
+            }
+            table.push(row);
+        }
+        table
+    })
+}