alphabetaengine.cpp

这是使用 C++ 写的棋子游戏

// AlphaBetaEngine.cpp: implementation of the CAlphaBetaEngine class.
//
//////////////////////////////////////////////////////////////////////

#include "AlphaBetaEngine.h"
#include <string.h>
#include <stdio.h>

//////////////////////////////////////////////////////////////////////
// Construction/Destruction
//////////////////////////////////////////////////////////////////////

CAlphaBetaEngine::CAlphaBetaEngine()
{

}

CAlphaBetaEngine::~CAlphaBetaEngine()
{

}

void CAlphaBetaEngine::SearchAGoodMove(BYTE position[][9])
{
    memcpy(CurPosition,position,90);    //将当前局面复制到CurPosition

    m_nMaxDepth=m_nSearchDepth;         //设定搜索深度
    AlphaBeta(m_nMaxDepth,-20000,20000);//进行alphabeta搜索
    m_umUndoMove.cmChessMove=m_cmBestMove;
    m_umUndoMove.nChessID=MakeMove(&m_cmBestMove);  

    memcpy(position,CurPosition,90);    //将走过的棋盘传出
}

int CAlphaBetaEngine::AlphaBeta(int nDepth,int alpha,int beta)
{
    int score;
    int Count,i;
    BYTE type;

	printf("%s: gets line %d\n", __FUNCTION__, __LINE__);
	printf("depth=%d\n", nDepth);
    i=IsGameOver(CurPosition,nDepth);//检查是否游戏结束
    if(i!=0)
        return i;//结束，返回估值

	printf("%s: gets line %d\n", __FUNCTION__, __LINE__);
    //叶子节点取估值
    if(nDepth<=0)
        return m_pEval->Eveluate(CurPosition,(m_nMaxDepth-nDepth)%2,m_nUserChessColor);

	printf("%s: gets line %d\n", __FUNCTION__, __LINE__);
    //此函数找出当前局面所有可能的走法，然后放进m_pMG ->m_MoveList当中
    Count=m_pMG->CreatePossibleMove(CurPosition,nDepth,(m_nMaxDepth-nDepth)%2,m_nUserChessColor);
    if(nDepth==m_nMaxDepth)
    {
        //在根节点设定进度条
        progress->setTotalSteps(Count);
        progress->setProgress(1);
    }
	printf("%s: gets line %d\n", __FUNCTION__, __LINE__);

    //对所有可能的走法
    for(i=0;i<Count;i++)
    {       
        if(nDepth==m_nMaxDepth)
            progress->nextStep();
	printf("%s: gets line %d\n", __FUNCTION__, __LINE__);

        type=MakeMove(&m_pMG->m_MoveList[nDepth][i]);  //将当前局面应用此走法，变为子节点的局面
        score=-AlphaBeta(nDepth-1,-beta,-alpha);       //递归搜索子节点
        UnMakeMove(&m_pMG->m_MoveList[nDepth][i],type);//将此节点的局面恢复为当前节点

        if(score>alpha)
        {
            alpha=score;//保留极大值

            //靠近根节点时保留最佳走法
            if(nDepth==m_nMaxDepth)
                m_cmBestMove=m_pMG->m_MoveList[nDepth][i];
        }
        
        if(alpha>=beta)
            break;//剪枝，放弃搜索剩下的节点
    }

    return alpha;//返回极大值
}