bool ChessBoard::isLegalMove(int mv)
{
int sqSrc, sqDst, pcSrc, pcDst;
sqSrc = SRC(mv);
sqDst = DST(mv);
if (sqSrc==sqDst)
{
return false;
}
pcSrc = m_data[sqSrc];
pcDst = m_data[sqDst];
if (side(pcSrc)==side(pcDst))
{
return false;
}
Moves mvs;
generateMoves(sqSrc, mvs);
for(int i=0; i<mvs.count(); i++)
{
if (mvs[i]==mv)
{
return true;
}
}
return false;
}
int ChessBoard::test1_max(int depth, int& mv)
{
if (depth==0)
{
mv = 0;
return m_vlBlack - m_vlRed;
}
Moves mvs;
//int selfSide = m_sdPlayer;
int best = -999999;
generateMoves(mvs);
for(int i=0; i<mvs.count(); i++)
{
int oldVal = m_vlBlack - m_vlRed;
int pcCapture;
if (makeMove(mvs[i], pcCapture))
{
int temp_mv;
int val = test1_min(depth-1, temp_mv);
if (val>best)
{
best = val;
mv = mvs[i];
}
undoMakeMove(mvs[i], pcCapture);
}
int newVal = m_vlBlack - m_vlRed;
Q_ASSERT(oldVal==newVal);
}
return best;
}
bool ChessBoard::IsMate()
{
//qDebug()<<"check isMate side="<<m_sdPlayer;
//int selfSide = m_sdPlayer;
Moves mvs;
generateMoves(mvs);
for(int i=0; i<mvs.count(); i++)
{
//qDebug()<<"尝试解招："<< mvString(mvs[i]);
int pcCaptured = _movePiece(mvs[i]);
if (!isChecked())
{
_undoMovePiece(mvs[i], pcCaptured);
//qDebug()<<"!!!解招："<< mvString(mvs[i]);
return false;
}
else{
_undoMovePiece(mvs[i], pcCaptured);
}
}
return true;
}
int ChessBoard::negaMax(int depth, int& mv)
{
if (depth==0)
{
return m_sdPlayer?m_vlBlack - m_vlRed:m_vlRed - m_vlBlack;
}
m_searchCallTimes++;
int best = INT_MIN;
Moves mvs;
generateMoves(mvs);
for(int i=0; i<mvs.count(); i++)
{
int oldVal = m_vlBlack - m_vlRed;
int pcCapture;
//qDebug()<<mvString(mvs[i]);
if (makeMove(mvs[i], pcCapture))
{
int temp_mv;
int val = -1 * negaMax(depth-1, temp_mv);
if (temp_mv)
{
//qDebug()<<mvString(temp_mv)<<" 评分"<<val;
}
if (val>best)
{
best = val;
mv = mvs[i];
}
undoMakeMove(mvs[i], pcCapture);
//qDebug()<<"UndoMakeMove";
}
int newVal = m_vlBlack - m_vlRed;
Q_ASSERT(oldVal==newVal);
}
return best;
}
int ChessBoard::alphaBetaSearch(int depth, int alpha, int beta)
{
//1.到达水平线返回
if (depth==0)
{
return evaluate();
}
m_searchCallTimes++;
//2.初使化最佳值,最佳走法
int vlBest = -MATE_VALUE;
int mvBest = 0;
//3.生成走法,根据历史表排序
Moves mvs;
generateMoves(mvs);
//PrintMoves(mvs);
qSort(mvs.begin(), mvs.end(), compareLessTan);
//PrintMoves(mvs);
//qDebug()<<"----------------------";
// 4. 逐一走这些走法，并进行递归
for(int i=0; i<mvs.count(); i++)
{
//列出走法
int pcCaptured;
if (makeMove(mvs[i], pcCaptured))
{
int vl = -alphaBetaSearch(depth - 1, -beta, -alpha);
undoMakeMove(mvs[i], pcCaptured);
//qDebug()<<mvString(mvs[i])<<" vl="<<vl;
//进行Alpha-Beta大小判断和截断
if (vl > vlBest)
{
// 找到最佳值(但不能确定是Alpha、PV还是Beta走法)
vlBest = vl; // "vlBest"就是目前要返回的最佳值，可能超出Alpha-Beta边界
if (vl >= beta)
{
// 找到一个Beta走法
mvBest = mvs[i]; // Beta走法要保存到历史表
break; // Beta截断
}
if (vl > alpha)
{
// 找到一个PV走法
mvBest = mvs[i]; // PV走法要保存到历史表
alpha = vl; // 缩小Alpha-Beta边界
}
}
}
}
// 5. 所有走法都搜索完了，把最佳走法(不能是Alpha走法)保存到历史表，返回最佳值
if (vlBest == -MATE_VALUE)
{
// 如果是杀棋，就根据杀棋步数给出评价
return m_distance - MATE_VALUE;
}
//qDebug()<<"mvBest="<<mvBest<<" distance="<<m_distance;
if (mvBest != 0)
{
// 如果不是Alpha走法，就将最佳走法保存到历史表
m_historyTable[mvBest] += depth * depth;
if (m_distance==0)
{
// 搜索根节点时，总是有一个最佳走法(因为全窗口搜索不会超出边界)，将这个走法保存下来
m_mvComputer = mvBest;
}
}
return vlBest;
}