Question

我有一个Javascript类，我需要克隆以在javascript中使用Alpha beta修剪创建minimax算法。但是当我将board对象传递给minimax函数时，它应该深度复制board对象然后进行更改，但它会对原始板进行更改。为什么要这样做？

var Buddha = function() {

  this.movehistory = 0;
  this.color = "b";
  this.opp = "w";

  this.clone = function(board) {
    return $.extend(true, {}, board)
  }

  this.minimax = function(board, depth, alpha, beta) {
    if(depth === 0 || board.game_over() === true) {
      return [this.eval_board(board), null]
    } else {
      if(board.turn() === "w") {
        var bestmove = null

        var possible_moves = board.moves()
        for (index = 0; index < possible_moves.length; ++index) {
          var new_board = this.clone(board)
          new_board.move(possible_moves[index])

          var mini = this.minimax(new_board, --depth, alpha, beta)
          var score = mini[0];
          var move = mini[1];

          if(score > alpha) {
            alpha = score;
            bestmove = possible_moves[index];
            if(alpha >= beta) {
              break;
            }
          }
        }
        return [alpha, bestmove]
      } else if(board.turn() === "b") {
        var bestmove = null

        var possible_moves = board.moves()
        for (index = 0; index < possible_moves.length; ++index) {
          var new_board = this.clone(board)
          new_board.move(possible_moves[index])

          var mini = this.minimax(new_board, --depth, alpha, beta)
          var score = mini[0];
          var move = mini[1];

          if(score < beta) {
            beta = score;
            bestmove = possible_moves[index];
            if(alpha >= beta) {
              break;
            }
          }
        }
        return [beta, bestmove]
      }
    }
  }

  this.eval_board = function(board) {
    if(board.in_check()) {
      if(board.turn() == this.opp) {
        return Number.POSITIVE_INFINITY;
      } else {
        return Number.NEGATIVE_INFINITY;
      }
    } else if(board.in_checkmate()) {
      if(board.turn() == this.opp) {
        return Number.POSITIVE_INFINITY;
      } else {
        return Number.NEGATIVE_INFINITY;
      }
    } else if(board.in_stalemate()) {
      if(board.turn() == this.opp) {
        return Number.POSITIVE_INFINITY;
      } else {
        return Number.NEGATIVE_INFINITY;
      }
    }
  }

  this.move = function(board) {
    console.log(board.fen());
    var bestmove = this.minimax(this.clone(board), 8, Number.POSITIVE_INFINITY, Number.NEGATIVE_INFINITY) 

    console.log(board.fen());
  }

}

控制台日志的输出是：

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1
R2r1b2/2q1k1p1/2n4n/2P2Q2/8/8/4K2P/1NBQ1BNR b - - 30 55

我的模块使用来自https://github.com/jhlywa/chess.js的chess.js api。

编辑：我已将其缩小到克隆功能，而不是正确克隆国际象棋功能。是因为Chess函数没有使用this装饰器声明变量吗？

Answer 1

chess.js库静态创建变量。难以克隆对象。幸运的是，Chess对象允许传递FEN变量。允许我像这样克隆电路板：

var clonedBoard = new Chess(oldBoard.fen());

这可以防止修改原始电路板。

对象未被克隆 - Javascript

1 个答案: