falphabetaengine.cpp

一个简单的象棋游戏源代码

// FAlphaBetaEngine.cpp: implementation of the CFAlphaBetaEngine class.
//
//////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "chess.h"
#include "FAlphaBetaEngine.h"

#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif

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

CFAlphaBetaEngine::CFAlphaBetaEngine()
{

}

CFAlphaBetaEngine::~CFAlphaBetaEngine()
{

}

CFAlphaBetaEngine::SearchAGoodMove(BYTE position[][9])
{
	memcpy(CurPosition,position,90);	 //复制传入的棋盘

	m_nMaxDepth=m_nSearchDepth;			 //设定搜索深度
	FAlphaBeta(m_nMaxDepth,-20000,20000);//调用fail-softalpha-beta
	m_umUndoMove.cmChessMove=m_cmBestMove;
	m_umUndoMove.nChessID=MakeMove(&m_cmBestMove);	

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

int CFAlphaBetaEngine::FAlphaBeta(int nDepth,int alpha,int beta)
{
	int current=-20000;//current初始为极小值
	int score;
	int Count,i;
	BYTE type;
	
	i=IsGameOver(CurPosition,nDepth);//检查此节点游戏是否结束
	if(i!=0)
		return i;//此节点游戏结束，返回极大/极小值

	//如果是叶子节点取估值
	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)
	{
		//在根节点设定进度条
		m_pThinkProgress->SetRange(0,Count);
		m_pThinkProgress->SetStep(1);
	}

	for(i=0;i<Count;i++)
	{
		if(nDepth==m_nMaxDepth)
			m_pThinkProgress->StepIt();//走进度条

		type=MakeMove(&m_pMG->m_MoveList[nDepth][i]);
		score=-FAlphaBeta(nDepth-1,-beta,-alpha);
		UnMakeMove(&m_pMG->m_MoveList[nDepth][i],type);

		if(score>current)
		{
			current=score;//保留最大值

			//当靠近根节点时记录最佳走法
			if(nDepth==m_nMaxDepth)
				m_cmBestMove=m_pMG->m_MoveList[nDepth][i];

			if(score>=alpha)
				alpha=score;//修改alpha边界

			if(score>=beta)
				break;//beta剪枝
		}
	}

	return current;//返回极大值或边界值
}