Method alphaBeta

MachineGame.cpp:197–241

}

int MachineGame::alphaBeta(int depth, int alpha, int beta, bool isMaximizing)
{
    if (depth == 0)
        return calcScore();

    // 检查将帅是否已死
    if (m_ChessPieces[4].m_bDead)  // 黑将死
        return m_bAiIsRed ? 100000 + depth : -(100000 + depth);
    if (m_ChessPieces[20].m_bDead) // 红帅死
        return m_bAiIsRed ? -(100000 + depth) : 100000 + depth;

    QVector<ChessStep*> steps;
    bool forRed = m_bIsRed;
    getAllMoves(steps, forRed);

    if (steps.isEmpty()) {
        return isMaximizing ? -(99999 + depth) : (99999 + depth);
    }

    // 走法排序：吃子走法优先
    std::sort(steps.begin(), steps.end(), [](ChessStep* a, ChessStep* b) {
        return (a->m_nKillID != -1) > (b->m_nKillID != -1);
    });

    int bestVal = isMaximizing ? INT_MIN : INT_MAX;

    for (auto* step : steps) {
        fakeMove(step);
        int val = alphaBeta(depth - 1, alpha, beta, !isMaximizing);
        unFakeMove(step);

        if (isMaximizing) {
            if (val > bestVal) bestVal = val;
            if (val > alpha) alpha = val;
        } else {
            if (val < bestVal) bestVal = val;
            if (val < beta) beta = val;
        }
        if (alpha >= beta)
            break;
    }

    for (auto* s : steps) delete s;
    return bestVal;
}

ChessStep* MachineGame::getBestMove()
{