**fig10_66.txt**

/* 1*/	    // Supporting types.
/* 2*/	enum Value_Type  { Comp_Loss, Draw, Comp_Win };
/* 3*/	enum Player_Type { Comp, Human };
/* 4*/	typedef int Board_Type[ 10 ];

/* 5*/	    // Supporting routines.
/* 6*/	int Full_Board( Board_Type B );
/* 7*/	int Immediate_Win( Board_Type B, int & Move, Player_Type P );
/* 8*/	void Place( Board_Type B, int Square, Player_Type P );
/* 9*/	int Is_Empty( Board_Type B, int Square );
/*10*/	void Unplace( Board_Type B, int Square );
/*11*/	void Find_Human_Move( Board_Type & B, int &, int & Value );


/* 1*/	// Recursive procedure to find best move for computer.
/* 2*/	// Best_Move is a number from 1-9 indicating square.
/* 3*/	// Possible evaluations satisfy Comp_Loss < Draw < Comp_Win.
/* 4*/	// Complementary routine Find_Human_Move isin Fig. 10.67. .
/* 5*/	// Board_Type is an array; thus Board can be changed by Place( ).

/* 6*/	void
/* 7*/	Find_Comp_Move( Board_Type & Board, int & Best_Move, int & Value )
/* 8*/	{
/* 9*/	    int Dc, i, Response;		// Dc means don't care.

/*10*/	    if( Full_Board( Board ) )
/*11*/	        Value = Draw;
/*12*/	    else
/*13*/	    if( Immediate_Win( Board, Best_Move, Comp ) )
/*14*/	        Value = Comp_Win;
/*15*/	    else
/*16*/	    {
/*17*/	        Value = Comp_Loss;
/*18*/	        for( i = 1; i <= 9; i++ )	// Try each square.
/*19*/	        {
/*20*/	            if( Is_Empty( Board, i ) )
/*21*/	            {

/*22*/	                Place( Board, i, Comp );
/*23*/	                Find_Human_Move( Board, Dc, Response );
/*24*/	                Unplace( Board, i );   	// Restore board.

/*25*/	                if( Response > Value )	// Update best move.
/*26*/	                {
/*27*/	                    Value = Response;
/*28*/	                    Best_Move = i;
/*29*/	                }
/*30*/	            }
/*31*/	        }
/*32*/	    }
/*33*/	}