/*
Author : Narendrakumar Padmani
Email  : n.padmani@yahoo.co.uk
*/
#include<stdio.h>
#include<conio.h>
#include<graphics.h>
int ws[4][4]={{0,0,0,0},{0,3,2,3},{0,2,4,2},{0,3,2,3}};
int ws2[4][4]={{0,0,0,0},{0,3,2,3},{0,2,4,2},{0,3,2,3}};
void copyarray(void)
	{
	int i,j;
	for(i=1;i<=4;i++)
		for(j=1;j<=4;j++)
			ws[i][j]=ws2[i][j];
	}
int getrow(int x)
	{
	return (x-1)/3+1;
	}
int getcol(int y)
	{
	return (y-1)%3+1;
	}
void putcircle(int block)
	{
	circle((getcol(block)-1)*100+50,(getrow(block)-1)*100+50,30);
	}
void putchokdi(int block)
	{
	int r=getcol(block),c=getrow(block);
	r=100*(r-1)+50;
	c=100*(c-1)+50;
	line(r-30,c-30,r+30,c+30);
	line(r+30,c-30,r-30,c+30);
	}
void grid(void)
	{
	line(100,0,100,300);
	line(200,0,200,300);
	line(0,100,300,100);
	line(0,200,300,200);
	}
void print_array(void)
	{
	int i,j;
	clrscr();
	for(i=1;i<=3;i++)
		{
		for(j=1;j<=3;j++)
			if(ws[i][j]==-1)
				printf(" x|");
			else if(ws[i][j]==-2)
				printf(" 0|");
			else
				printf("  |",ws[i][j]);
		printf("\n");
		}
	return;
	}
int get_highest(void)
	{
	int	i,max=ws[1][1],key=1;
	for(i=2;i<=9;i++)
		if(ws[getrow(i)][getcol(i)]>max)
			{
			max=ws[getrow(i)][getcol(i)];
			key=i;
			}
	return key;
	}
void desc(int pos)
	{
	if(ws[getrow(pos)][getcol(pos)]>0)
		ws[getrow(pos)][getcol(pos)]--;
	return ;
	}
void calculate(int pos)
	{
	int r,c,t;
	r=getrow(pos);
	c=getcol(pos);
	r=3*(r-1)+1;
	for(t=1;t<=3;t++)
		{
		desc(r);
		desc(c);
		r++;
		c+=3;
		}
	if(pos==1 || pos==5 || pos==9)
		{
		desc(1);
		desc(5);
		desc(9);
		}
	if(pos==3 || pos==5 || pos==7)
		{
		desc(3);
		desc(5);
		desc(7);
		}
	}
int check2(int sym)
	{
	int i,j,t_sym,index,blank,k;
	for(i=1;i<=3;i++)
		{
		t_sym=0;
		blank=0;
		index=0;
		for(j=1;j<=3;j++)
			if(ws[i][j]==sym)
				t_sym++;
			else if(ws[i][j]>=0)
				{
				blank++;
				index=3*(i-1)+j;
				}
		if(t_sym==2 && blank==1)
			return index;
		}
	for(i=1;i<=3;i++)
		{
		t_sym=0;
		blank=0;
		index=0;
		for(j=1;j<=3;j++)
			if(ws[j][i]==sym)
				t_sym++;
			else if(ws[j][i]>=0)
				{
				blank++;
				index=3*(j-1)+i;
				}
		if(t_sym==2 && blank==1)
			return index;
		}
	t_sym=0;
	blank=0;
	for(k=3;k<=7;k+=2)
		{
		i=getrow(k);
		j=getcol(k);
		if(ws[i][j]==sym)
				t_sym++;
			else if(ws[i][j]>=0)
				{
				blank++;
				index=3*(i-1)+j;
				}
		if(t_sym==2 && blank==1)
			return index;
		}
	t_sym=0;
	blank=0;
	for(k=1;k<=9;k+=4)
		{
		i=getrow(k);
		j=getcol(k);
		if(ws[i][j]==sym)
				t_sym++;
			else if(ws[i][j]>=0)
				{
				blank++;
				index=3*(i-1)+j;
				}
		if(t_sym==2 && blank==1)
			return index;
		}
	return -1;
	}
int count(void)
	{
	int i,j,k=0;
	for(i=1;i<=3;i++)
		for(j=1;j<=3;j++)
			if(ws[i][j]<0)
				k++;
	return k;
	}
int dilemma(void)
	{
	if(count()==3 && ( (ws[1][1]==-1 && ws[3][3]==-1 && ws[2][2]==-2) || (ws[1][3]==-1 && ws[3][1]==-1 && ws[2][2]==-2)))
		return 1;
	else
		return -1;
	}
int tictactoe_engine(void)
	{
	int i,r,c,index;
	while(1)
		{
		//print_array();
		i=(getch()-48);
		if(i<0 || i>9)
			continue;
		if(i==0)
			return -1;
		r=getrow(i);
		c=getcol(i);
		if(ws[r][c]==-1 || ws[r][c]==-2)
			continue;
		ws[r][c]=-1;
		putchokdi(i);
		if((index=check2(-2))!=-1)
			{
			ws[getrow(index)][getcol(index)]=-2;
			putcircle(index);
			return 1;
			}
		else if((index=check2(-1))!=-1)
			{
			calculate(index);
			ws[getrow(index)][getcol(index)]=-2;
			putcircle(index);
			}
		else if(dilemma()==1)
			{
			index=8;
			calculate(index);
			ws[getrow(index)][getcol(index)]=-2;
			putcircle(index);
			}
		else
			{
			index=get_highest();
			if(ws[getrow(index)][getcol(index)]>=0)
				{
				calculate(index);
				ws[getrow(index)][getcol(index)]=-2;
				putcircle(index);
				}
			}
		if(count()==9)
			return 0;

		}
	}
int main(void)
	{
	int i;
	int gdriver = DETECT, gmode, errorcode;
	initgraph(&gdriver, &gmode, "");
	//setlinestyle(1,0,1);
	grid();
	while(1)
		{
		i=tictactoe_engine();
		if(i==1)
			outtextxy(400,400,"Computer Wins !");
		else if(i==0)
			outtextxy(400,400,"Match Draw !");
		else
			break;
		outtextxy(400,430,"To continue..press y");
		if(getch()=='y')
			{
			cleardevice();
			grid();
			copyarray();
			}

		else
			break;
		}
	closegraph();
	return 0;
	}