Thread: help with tic tac toe look ahead algorithm

i have been stuck here around a week...can you pls give me some idea how to start it? thanks..here is my codes for the TTT.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <time.h>

void makeboard();
void printboard();
int checkwin();
void makemove(int move, int counter);
int lookahead();
int computermove(int turn,int counter);
int chkcompmove(int move);
int getmove(int counter);
int enemymove(int);

char board[3][3]={0};
char tempboard[3][3]={0};

int turn, win, counter, X,O, lahlvl, compmove,chkcomp, move;

int main(void){
	win=0;
	srand(time(NULL));
	printf("X is [1] human, [2] computer :");
	scanf("%d",&X);
	printf("O is [1] human, [2] computer :");
	scanf("%d",&O);
	printf("Set lookahead level[0-3]:");
	scanf("%d",&lahlvl);

	makeboard();
	turn=1;
	while(win==0&&turn!=10)
	{
		turn++;
		counter=turn%2;
		switch(counter)
		{
		case 0: 
			if(X==1)
			{
				printboard();
				move=getmove(counter);
				makemove(move, counter);
				win=checkwin();
				break;
			}
			else
			{
				move=computermove(turn, counter);
				makemove(move, counter);
				win=checkwin();
				break;
			}

		case 1: 
			if(O==1)
			{
				printboard();
				move=getmove(counter);
				makemove(move, counter);
				win=checkwin();			
			break;
			}
			else
			{
				move=computermove(turn, counter);
				makemove(move, counter);
				win=checkwin();
				break;
			}
			
		}			
	}
	if(turn==10)
	{
		printboard();
		printf("Draw!\n");
	}
	else if(counter==0)
	{
		printboard();
		printf("X wins!\n");
	}
	else if(counter==1)
	{
		printboard();
		printf("O wins!\n");
	}
	
	return(0);
}

void makeboard() {
	int a,b;
	char c='1';
	
		for (a=0;a<3;a++)
	{
		for (b=0;b<3;b++)
		{
			board[a][b]=c;
			c+=1;
		}
	}
}

void printboard() {
	
	int a,b;
	
	for (a=0;a<3;a++)
		{
			for (b=0;b<3;b++)
			{
				printf("%c",board[a][b]);
			}
			printf("\n");
		}
}

void makemove(int move,int counter) {
	switch(move)
	{
	case 1:
		if(board[0][0]!='1')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[0][0]='X';
			else
				board[0][0]='O';
			break;

		}

		
	
	case 2:
		if(board[0][1]!='2')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[0][1]='X';
			else
				board[0][1]='O';
			break;
		}
		
	
	case 3:
		if(board[0][2]!='3')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[0][2]='X';
			else
				board[0][2]='O';
			break;
		}
	

	case 4:
		if(board[1][0]!='4')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[1][0]='X';
			else
				board[1][0]='O';
			break;
		}

	case 5:
		if(board[1][1]!='5')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[1][1]='X';
			else
				board[1][1]='O';
			break;
		}
		

	case 6:
		if(board[1][2]!='6')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[1][2]='X';
			else
				board[1][2]='O';
			break;
		}

	case 7:
		if(board[2][0]!='7')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[2][0]='X';
			else
				board[2][0]='O';
			break;
		}
		

	case 8:
		if(board[2][1]!='8')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[2][1]='X';
			else
				board[2][1]='O';
			break;
		}
	
	case 9:
		if(board[2][2]!='9')
		{
			printf("invalid move\n");
			move=getmove(counter);
			makemove(move, counter);
			break;
		}
		else
		{	
			if(counter==0)
				board[2][2]='X';
			else
				board[2][2]='O';
			break;
		}
	}
}

int getmove(int counter) {
	if(counter==0)
	{
		printf("X move:");
		scanf("%d",&move);
	}
	else
	{
		printf("O move:");
		scanf("%d",&move);
	}
	return move;
}

int checkwin() 
	{
	int a=0,b=0;
	for (a=0;a<3;a++)
	{
		if (board[a][b]=='O' && board[a][b+1]=='O' && board[a][b+2]=='O')
		{
				return 1;
			
		}
		else if (board[a][b]=='X' && board[a][b+1]=='X' && board[a][b+2]=='X')
		{
				return 1;
		}
	}
	a=0;
	for (b=0;b<3;b++)
	{
		if (board[a][b]=='O' && board[a+1][b]=='O' && board[a+2][b]=='O')
		{
				return 1;
		}
		else if (board[a][b]=='X' && board[a+1][b]=='X' && board[a+2][b]=='X')
		{	
				return 1;
		}
	}
	a=0;
	b=0;
	if (board[a][b]=='O' && board[a+1][b+1]=='O' && board[a+2][b+2]=='O')
	{
				return 1;
	}
	else if (board[a][b]=='X' && board[a+1][b+1]=='X' && board[a+2][b+2]=='X')
	{
				return 1;
	}
	else if (board[a][b+2]=='O' && board[a+1][b+1]=='O' && board[a+2][b]=='O')
	{
				return 1;
	}
	else if (board[a][b+2]=='X' && board[a+1][b+1]=='X' && board[a+2][b]=='X')
	{
				return 1;
	}
	return 0;
}

int chkcompmove(int compmove){

switch(compmove)
	{
	case 1:
		if(board[0][0]!='1')
		{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 2:
		if(board[0][1]!='2')
		{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 3:
		if(board[0][2]!='3')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 4:
		if(board[1][0]!='4')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 5:
		if(board[1][1]!='5')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 6:
		if(board[1][2]!='6')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 7:
		if(board[2][0]!='7')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 8:
		if(board[2][1]!='8')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	case 9:
		if(board[2][2]!='9')
			{
			return 0;
			break;
		}
		else
		{	
			return 1;
			break;
		}
	}
return 0;
}

int computermove(int turn,int counter)
{	
	int comp,a,b;
	tempboard[3][3]=board[3][3];
	for (a=0;a<3;a++)
		{
			for (b=0;b<3;b++)
			{
				tempboard[a][b]=board[a][b];
			}
	}
	if(turn==2)
	{
	switch(compmove)
		{
		case 0:
			return 1;
			break;
		case 1:
			return 2;
			break;
		case 3:
			return 5;
			break;

		}
	}
	else
	{
		if(lahlvl==0)
		{
			chkcomp=0;

			while(chkcomp==0)
			{
				compmove=rand()%9+1;
				chkcomp=chkcompmove(compmove);
			}
			return compmove;
		}
		if (lahlvl==2 || lahlvl==3)	
		{
			chkcomp=lookahead();
			return compmove;
		}
		
	}
	
return 0;
}

int lookahead()
{
	int n=lahlvl,a,b,ahead,marks[3][3]={a},check=0,cpu,player;
	
	/*marks not initialized to 0 for checking purpose*/
	
	for (a=0;a<3;a++)
	{
		for (b=0;b<3;b++)
		{	
			for (ahead==0;ahead<n;ahead++)	/*for the number of look ahead*/
			{
				if (isdigit(tempboard[a][b]!=0)
				{
					cpu = tempboard[a][b];
					player= enemymove();
					check=checkwin();
					if (check ==1)
						mark[a][b]=1;
					



int enemymove();
{
	compmove=rand()%9+1;
	chkcomp=chkcompmove(compmove);

the ending is the place where i got stuck... >_<