Java中的井字游戏AI极小极大函数答案

【问题标题】：Tic-Tac-Toe AI minimax function in JavaJava中的井字游戏AI极小极大函数
【发布时间】：2023-03-25 15:51:01
【问题描述】：

这里有我的极小极大算法代码。它似乎做出了明智的决定，但并非总是如此，这不应该发生，我需要帮助，因为我似乎找不到哪里出错了。

private char level2Move() {
  try {
    NBoard game_copy = (NBoard) game.clone();

    int bestScore = Integer.MIN_VALUE;
    char bestMove = '-';

    for (char move: game_copy.getValidMoves()) {
      game_copy.enterMove(move);
      int score = minimax(game_copy, true);
      game_copy.undoMove();
      if (score > bestScore) {
        bestScore = score;
        bestMove = move;
      }
    }

    return bestMove;
  } catch(CloneNotSupportedException e) {
    e.printStackTrace();
  }

  return '-';
}

public int minimax(NBoard game, boolean isMaximizing) {
  int bestScore;

  switch (game.getGameState()) {
  case NBoard.X_WIN:
    return - 10;
  case NBoard.O_WIN:
    return 10;
  case NBoard.DRAW:
    return 0;
  }

  if (isMaximizing) {
    bestScore = Integer.MIN_VALUE;
    for (char move: game.getValidMoves()) {
      if (game.getGameState() == NBoard.ONGOING) {
        game.enterMove(move);
        int score = minimax(game, false);
        game.undoMove();
        bestScore = Math.max(score, bestScore);
      }
    }
  } else {
    bestScore = Integer.MAX_VALUE;
    for (char move: game.getValidMoves()) {
      if (game.getGameState() == NBoard.ONGOING) {
        game.enterMove(move);
        int score = minimax(game, true);
        game.undoMove();
        bestScore = Math.min(score, bestScore);
      }
    }
  }
  return bestScore;
}

棋盘输入（移动）是字母A-I，像这样......

A|B|C
D|E|F
G|H|I

我似乎还没有使用“分数”，并且正在考虑增加深度，但我想不出这会有什么帮助。

【问题讨论】：

你确定你计算的 WDL 正确吗？如果它有时会做出好的动作，它似乎会做出随机动作，或者总是选择它尝试的第一个动作。

标签： java tic-tac-toe minimax

【解决方案1】：

我修好了。只需更改 minimax 函数中的布尔值即可。

private char level2Move() {
  try {
    NBoard game_copy = (NBoard) game.clone();

    int bestScore = Integer.MIN_VALUE;
    char bestMove = '-';

    for (char move: game_copy.getValidMoves()) {
      game_copy.enterMove(move);
      int score = minimax(game_copy, false);       // here
      game_copy.undoMove();
      if (score > bestScore) {
        bestScore = score;
        bestMove = move;
      }
    }

    return bestMove;
  } catch(CloneNotSupportedException e) {
    e.printStackTrace();
  }

  return '-';
}

public int minimax(NBoard game, boolean isMaximizing) {
  int bestScore;

  switch (game.getGameState()) {
  case NBoard.X_WIN:
    return - 10;
  case NBoard.O_WIN:
    return 10;
  case NBoard.DRAW:
    return 0;
  }

  if (isMaximizing) {
    bestScore = Integer.MIN_VALUE;
    for (char move: game.getValidMoves()) {
      if (game.getGameState() == NBoard.ONGOING) {
        game.enterMove(move);
        int score = minimax(game, false);          // here
        game.undoMove();
        bestScore = Math.max(score, bestScore);
      }
    }
  } else {
    bestScore = Integer.MAX_VALUE;
    for (char move: game.getValidMoves()) {
      if (game.getGameState() == NBoard.ONGOING) {
        game.enterMove(move);
        int score = minimax(game, true);           // here
        game.undoMove();
        bestScore = Math.min(score, bestScore);
      }
    }
  }
  return bestScore;
}

【讨论】：