**fig10_73.txt**

/* 1*/	// Same as before, but perform alpha-beta pruning.
/* 2*/	// The main routine should make the call with:
/* 3*/	// Alpha = Comp_Loss, Beta = Comp_Win.

/* 4*/	void
/* 5*/	Find_Comp_Move( Board_Type & Board, int & Best_Move, int & Value,
/* 6*/	            int Alpha, int Beta )
/* 7*/	{
/* 8*/	    int Dc, i, Reply;		// Dc means don't care.

/* 9*/	    if( Full_Board( Board ) )
/*10*/	        Value = Draw;
/*11*/	    else
/*12*/	    if( Immediate_Win( Board, Best_Move, Comp ) )
/*13*/	        Value = Comp_Win;
/*14*/	    else
/*15*/	    {
/*16*/	        Value = Alpha;
/*17*/	        for( i = 1; i <= 9 && Value < Beta; i++ )
/*18*/	        { 	// Try each square.
/*19*/	            if( Is_Empty( Board, i ) )
/*20*/	            {

/*21*/	                Place( Board, i, Comp );
/*22*/	                Find_Human_Move( Board, Dc, Reply, Value, Beta );
/*23*/	                Unplace( Board, i );      // Restore Board.

/*24*/	                if( Reply > Value )    // Update best move.
/*25*/	                {
/*26*/	                    Value = Reply;
/*27*/	                    Best_Move = i;
/*28*/	                }
/*29*/	            }
/*30*/	        }
/*31*/	    }
/*32*/	}