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// AlphaBetaEngine.cpp: implementation of the CAlphaBetaEngine class. 
// 
////////////////////////////////////////////////////////////////////// 
 
#include "stdafx.h" 
#include "AlphaBetaEngine.h" 
 
////////////////////////////////////////////////////////////////////// 
// Construction/Destruction 
////////////////////////////////////////////////////////////////////// 
 
CAlphaBetaEngine::CAlphaBetaEngine() 
{ 
 
} 
 
CAlphaBetaEngine::~CAlphaBetaEngine() 
{ 
 
} 
 
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; 
 
	i=IsGameOver(CurPosition,nDepth);//检查是否游戏结束 
	if(i!=0) 
		return i;//结束，返回估值 
 
	//叶子节点取估值 
	if(nDepth<=0) 
		return m_pEval->Eveluate(CurPosition,(m_nMaxDepth-nDepth)%2,m_nUserChessColor); 
 
	//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 
		m_pThinkProgress->SetRange(0,Count); 
		m_pThinkProgress->SetStep(1); 
	} 
 
	//对所有可能的走法 
	for(i=0;iStepIt();//走进度条 
 
		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 
}