pvs_engine.cpp

这是使用 C++ 写的棋子游戏

// PVS_Engine.cpp: implementation of the CPVS_Engine class.
//
//////////////////////////////////////////////////////////////////////

#include "PVS_Engine.h"

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

CPVS_Engine::CPVS_Engine()
{

}

CPVS_Engine::~CPVS_Engine()
{

}

void CPVS_Engine::SearchAGoodMove(BYTE position[][9])
{
    memcpy(CurPosition,position,90);

    m_nMaxDepth=m_nSearchDepth;
    PrincipalVariation(m_nMaxDepth,-20000,20000);   
    m_umUndoMove.cmChessMove=m_cmBestMove;
    m_umUndoMove.nChessID=MakeMove(&m_cmBestMove);  

    memcpy(position, CurPosition, 90);
}

int CPVS_Engine::PrincipalVariation(int nDepth, int alpha, int beta)
{
    int score;
    int Count,i;
    BYTE type;
    int best;

    i=IsGameOver(CurPosition, nDepth);
    if(i!=0)
        return i;

    //叶子节点取估值
    if(nDepth<=0)
        return m_pEval->Eveluate(CurPosition,(m_nMaxDepth-nDepth)%2,m_nUserChessColor);
    
    Count=m_pMG->CreatePossibleMove(CurPosition,nDepth,(m_nMaxDepth-nDepth)%2,m_nUserChessColor);
    if(nDepth==m_nMaxDepth)
    {
        progress->setTotalSteps(Count);
        progress->setProgress(1);
    }
    
    type=MakeMove(&m_pMG->m_MoveList[nDepth][0]);   //产生第一个节点
    best=-PrincipalVariation(nDepth-1,-beta,-alpha);//使用全窗口搜索第一个节点
    UnMakeMove(&m_pMG->m_MoveList[nDepth][0],type); //撤销第一个节点 
    
    //靠近根节点保存最佳走法
    if(nDepth==m_nMaxDepth)
        m_cmBestMove=m_pMG->m_MoveList[nDepth][0];
    
    //从第二个节点起，对每一节点
    for(i=1;i<Count;i++)
    {
        if(nDepth==m_nMaxDepth)
            progress->nextStep();

        if(best<beta)//如果不能Beta剪枝
        {
            if(best>alpha)
                alpha=best;

            type=MakeMove(&m_pMG->m_MoveList[nDepth][i]);       //产生子个节点
            score=-PrincipalVariation(nDepth-1,-alpha-1,-alpha);//使用极窄窗搜索

            if(score>alpha && score<beta) 
            {
                best=-PrincipalVariation(nDepth-1,-beta,-score);//failhigh，重新搜索
                
                //靠近根节点保存最佳走法
                if(nDepth==m_nMaxDepth)
                    m_cmBestMove=m_pMG->m_MoveList[nDepth][i];
            }
            else
                if(score>best)
                {
                    best=score;//窄窗搜索命中
                    if(nDepth==m_nMaxDepth)
                        m_cmBestMove=m_pMG->m_MoveList[nDepth][i];
                }

            UnMakeMove(&m_pMG->m_MoveList[nDepth][i],type);//撤销子节点
        }
    }

    return best;//返回最佳值
}