我在使用极小极大算法开发自己的国际象棋引擎时遇到了问题。我使用了5层深度的搜索,并且只考虑了物质/奖励/机动性评估,但它仍然会做出愚蠢的走法,甚至在给定无限时间(这显然是搜索问题)时也牺牲了有价值的棋子。我没有使用任何类型的剪枝,并且在几秒钟内就能得到5层深度的搜索结果。
我已经为这个问题困扰了一个星期,我确信问题出在回溯上,而不是国际象棋逻辑上(所以即使是没有国际象棋背景的人也能解决这个问题:)),我已经做了很多搜索,这是我在Stack Overflow上的第一个问题,我希望你们不会让我失望:)
以下是简单的搜索代码
int GameControl::Evaluate(ChessBoard _B){ int material=0,bonus=0,mobility=0; for(int i=0;i<8;i++) for(int j=0;j<8;j++) { if(_B.Board[i][j]!=EMPTY) { if(_B.Board[i][j]->pieceColor==WHITE){ material+=-_B.Board[i][j]->Weight; bonus+=-_B.Board[i][j]->bonusPosition[i][j]; mobility+=-_B.Board[i][j]->getPossibleMovesList(i,j,B).size(); } else { material+=_B.Board[i][j]->Weight; bonus+=_B.Board[i][j]->bonusPosition[i][j]; mobility+=_B.Board[i][j]->getPossibleMovesList(i,j,B).size(); } } } return material+bonus/10+mobility/20;}pair<pair<int,int>,pair<int,int>> GameControl::minimax( int depth , ChessBoard _B ){ short int i,j; int bestValue = -INFINITY; pair<pair<int,int>,pair<int,int>> bestMove; vector< pair<int,int> > ::iterator it; vector< pair<int,int> > Z; for( i = 0; i < 8; i++ ) for( j = 0; j < 8; j++ ) { if(_B.Board[i][j]!=EMPTY && _B.Board[i][j]->pieceColor==BLACK ) { Z=_B.Board[i][j]->getPossibleMovesList(i,j,_B); for(it=Z.begin();it!=Z.end();it++) { pair<int,int> temp; temp.first=i,temp.second=j; ChessPieces* DestinationPiece; DestinationPiece=_B.Board[(*it).first][(*it).second]; //Moving _B.Board[(*it).first][(*it).second]=_B.Board[i][j]; _B.Board[i][j]=EMPTY; // int value = minSearch( depth-1 , _B ); if( value > bestValue ) { bestValue = value; bestMove.first.first = i; bestMove.first.second = j; bestMove.second.first = (*it).first; bestMove.second.second = (*it).second; } //Undo Move _B.Board[i][j]=_B.Board[((*it).first)][(*it).second]; _B.Board[(*it).first][(*it).second]=DestinationPiece; } } } return bestMove;}int GameControl::minSearch( int depth , ChessBoard _B ){ short int i; short int j; if(depth==0) return Evaluate(_B); int bestValue = INFINITY; for( i = 0; i < 8; i++ ) for( j = 0; j < 8; j++ ) { vector< pair<int,int> > ::iterator it; vector< pair<int,int> > Z; if(_B.Board[i][j]!=EMPTY && _B.Board[i][j]->pieceColor==WHITE && !_B.Board[i][j]->V.empty()) { Z=_B.Board[i][j]->getPossibleMovesList(i,j,_B); for(it=Z.begin();it!=Z.end();it++) { pair<int,int> temp; temp.first=i; temp.second=j; ChessPieces* DestinationPiece; DestinationPiece=_B.Board[(*it).first][(*it).second]; // Moving _B.Board[(*it).first][(*it).second]=_B.Board[i][j]; _B.Board[i][j]=EMPTY; // int value = maxSearch( depth-1 , _B ); if( value < bestValue ) bestValue = value; //Undo Move _B.Board[i][j]=_B.Board[(*it).first][(*it).second]; _B.Board[(*it).first][(*it).second]=DestinationPiece; // } } } return bestValue;}int GameControl::maxSearch( int depth , ChessBoard _B ){ short int i; short int j; if(depth==0) return Evaluate(_B); vector< pair<int,int> > ::iterator it; vector< pair<int,int> > Z; int bestValue = -INFINITY; for( i = 0; i < 8; i++ ) for( j = 0; j < 8; j++ ) { if(_B.Board[i][j]!=EMPTY && _B.Board[i][j]->pieceColor==BLACK ) { Z=_B.Board[i][j]->getPossibleMovesList(i,j,_B); for(it=Z.begin();it!=Z.end();it++) { pair<int,int> temp; temp.first=i,temp.second=j; ChessPieces* DestinationPiece; DestinationPiece=_B.Board[(*it).first][(*it).second]; //Moving _B.Board[(*it).first][(*it).second]=_B.Board[i][j]; _B.Board[i][j]=EMPTY; // int value = minSearch( depth-1 , _B ); if( value > bestValue ) bestValue = value; //Undo Move _B.Board[i][j]=_B.Board[((*it).first)][(*it).second]; _B.Board[(*it).first][(*it).second]=DestinationPiece; } } } return bestValue;}
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