#include <stdio.h>

void info()
{
	printf("TIC-TAC-TOE\nWritten by John Doe\n");
	printf("Your Symbol: 'x'\nComputer Symbol: 'o'");
}

void init(char cell[])
{
	cell[0] = ' ';
	cell[1] = ' ';
	cell[2] = ' ';
	cell[3] = ' ';
	cell[4] = ' ';
	cell[5] = ' ';
	cell[6] = ' ';
	cell[7] = ' ';
	cell[8] = ' ';
}

void gameBoard (char cell[])
{
	printf("\n %c | %c | %c \n", cell[0], cell[1], cell[2]);
   	printf("---|---|---\n");
   	printf(" %c | %c | %c \n", cell[3], cell[4], cell[5]);
   	printf("---|---|---\n");
   	printf(" %c | %c | %c \n\n", cell[6], cell[7], cell[8]);
}

void userMove (char cell[])
{
	int you;
	

	do
	{
		do
		{
			printf("Your Move (0-8):\n");
			scanf("%i", &you);
			if (you>=9) printf("Invalid Move\n");
		} while (you>=9);
		if (cell[you] != ' ') printf("Position taken\n");
	} while (cell[you] != ' ');
	cell[you]='x';
	gameBoard(cell);
}

void computerMove (char cell[])
{
	int i=0;
	do
	{
		if(cell[i]==' ') { cell[i]='o'; break; }
		++i;
	}while(i<=8);	
	printf("Computer Plays:%i\n", i);
	gameBoard(cell);
}

char checkWinner(char cell[])
{
	char x; int i;
	if((cell[0]=='x' && cell[1]=='x' && cell[2]=='x')
		|| (cell[0]=='x' && cell[3]=='x' && cell[6]=='x')
		|| (cell[0]=='x' && cell[4]=='x' && cell[8]=='x')
		|| (cell[1]=='x' && cell[4]=='x' && cell[7]=='x')
		|| (cell[2]=='x' && cell[5]=='x' && cell[8]=='x')
		|| (cell[2]=='x' && cell[4]=='x' && cell[6]=='x')
		|| (cell[3]=='x' && cell[4]=='x' && cell[5]=='x')
		|| (cell[6]=='x' && cell[7]=='x' && cell[8]=='x'))
		x = 'x';
	else if ((cell[0]=='o' && cell[1]=='o' && cell[2]=='o')
		|| (cell[0]=='o' && cell[3]=='o' && cell[6]=='o')
		|| (cell[0]=='o' && cell[4]=='o' && cell[8]=='o')
		|| (cell[1]=='o' && cell[4]=='o' && cell[7]=='o')
		|| (cell[2]=='o' && cell[5]=='o' && cell[8]=='o')
		|| (cell[2]=='o' && cell[4]=='o' && cell[6]=='o')
		|| (cell[3]=='o' && cell[4]=='o' && cell[5]=='o')
		|| (cell[6]=='o' && cell[7]=='o' && cell[8]=='o'))
		x = 'o';
	else {
		x = 'd';
		for (i=0; i<9; i++)
			if (cell[i] == ' ') { x = ' '; break; } 
	}
	return x;
}

int main()
{

	char cell[9], cW;
	info(cell);
	init(cell);
	gameBoard(cell);

	do {

		userMove(cell);
		cW = checkWinner(cell);
		if (cW != ' ') continue;

		computerMove(cell);
		cW = checkWinner(cell);
		if (cW != ' ') continue;
	
	} while (cW == ' ');

	if(cW == 'o')
		printf("Computer Wins! Better Luck Next Time\n");
	else if(cW == 'x')
		printf("You Win!\n");
	else if(cW == 'd')
		printf("Game Ends in a Tie!\n");

	return 0;
}