/**
* Same as before, but perform alpha-beta pruning.
* The main routine should make the call with
* alpha = COMP_LOSS and beta = COMP_WIN.
*/
int TicTacToe::findCompMove( int & bestMove, int alpha, int beta )
{
int i, responseValue;
int dc; // dc means don't care; its value is unused
int value;
if( fullBoard( ) )
value = DRAW;
else
if( immediateCompWin( bestMove ) )
return COMP_WIN; // bestMove will be set by immediateCompWin
else
{
value = alpha; bestMove = 1;
for( i = 1; i <= 9 && value < beta; i++ ) // Try each square
{
if( isEmpty( i ) )
{
place( i, COMP );
responseValue = findHumanMove( dc, value, beta );
unplace( i ); // Restore board
if( responseValue > value )
{
// Update best move
value = responseValue;
bestMove = i;
}
}
}
}
return value;
}
void TicTacToe::findCompMove(int& bestMove,int &value, int alpha, int beta) {
if (board.isFull())
value = Draw;
else if (board.immediateComWin(bestMove))
value = CompWin;
else {
value = alpha;
for (int i = 0; i < GridNuber&&value < beta; i++) {
if (board.isEmpty(i)) {
board.placeComp(i);
int tmp = -1, response = -1; // Tmp is useless
findHumanMove(tmp, response, value, beta);
board.unPlace(i);
if (response > value) {
value = response;
bestMove = i;
}
}
}
}
}
