Tic-Tac-Toe alogorithm

Question

I am writing a program for tic-tac-toe, where system will guess the next best move for one player. Any pointer how to solve it?

Answer 1

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

int check(int[][3]);
void print(int[][3]);

main()
{
 int i,j,match[3][3]={0},posx,posy,comp_posx,comp_posy,fill=0,slot,user_score=0,comp_score=0;
 char ch;
 srand(time(NULL));
 do
 {
  while(fill<9)
  {
   printf("\nEnter the slot you want to fill.\n");
   scanf("%d",&slot);
   if (slot > 9)
   {
    printf("Error!\nSlot value cannot exceed 9.\n");
    continue;
   }
   else if( slot >= 1&&slot <=3)
   {
    posx=0;
    posy=slot-1;
   }
   else if (slot >= 4 && slot <= 6)
   {
    posx=1;
    posy=slot-4;
   }
   else
   {
    posx=2;
    posy=slot-7;
   }
   if (match[posx][posy] == 0)
   {
    match[posx][posy]=1;
    fill++;
    check(match);
    if(check(match)==1)
    {
     printf("The user wins!\n");
     user_score++;
     print(match);
     break;
    }
    else if(check(match)==-1)
    {
     printf("The computer wins!\n");
     comp_score++;
     print(match);
    }
    else
    {
     if(fill==9)
     {
      printf("It's a draw!\n");
      print(match);
      break;
     }
     else
     {
      printf(" ");
     }
    }
   }
   else
   {
    printf("Sorry! This slot is already filled.\nPlease pick another slot.\n");
    continue;
   }
   label:
   comp_posx=rand()%3;
   comp_posy=rand()%3;
   if(match[comp_posx][comp_posy]==0)
   {
    match[comp_posx][comp_posy]=-1;
    fill++;
    check(match);
    if (check(match)==1)
    {
     printf("The user wins!\n");
     user_score++;
     print(match);
     break;
    }
    else if(check(match)==-1)
    {
     printf("The computer wins!\n");
     comp_score++;
     print(match);
     break;
    }
    else
    {
     if (fill==9)
     {
      printf("It's a draw!\n");
      print(match);
      break;
     }
     else
     {
      printf(" ");
     }
    }
   }
   else
   goto label;
   for(i=0;i<3;i++)
   {
    printf("\n");
    for(j=0;j<3;j++)
    {
    printf("%d\t",match[i][j]);
    }
   }
  }
  for(i=0;i<3;i++)
  {
   for(j=0;j<3;j++)
   {
    match[i][j]=0;
   }
  }
  printf("Continue? Y/N\n");
  scanf("%c %c",&ch,&ch);
 }
 while(ch=='y'||ch=='Y');
 printf("FINAL SCORES>>\nUser=%d\nComputer=%d\n",user_score,comp_score);
}
int check(int match[][3])
{
 int i,j;
 if( match[2][0]==match[1][1] && match[1][1]==match[0][2] )
 {
  if (match[0][2]==1)
  return 1;
  else if (match[0][2]==-1)
  return -1;
  else
  printf(" ");
 }
 for(i=0;i<3;i++)
 {
  if (match[i][0]==match[i][1]&&match[i][1]==match[i][2])
  {
   if(match[i][1]==1)
   return 1;
   else if(match[i][1]==-1)
   return -1;
   else
   continue;
  }
 }
 for(j=0;j<3;j++)
 {
  if(match[0][j]==match[1][j]&&match[0][j]==match[2][j])
  {
   if (match[0][j]==1)
   return 1;
   else if(match[0][j]==-1)
   return -1;
   else
   continue;
  }
 }
 for (i=0;i<1;i++)
 {
  if(match[i][i]==match[i+1][i+1]&&match[i][i]==match[i+2][i+2])
  {
   if (match[i][i]==1)
    return 1;
   else if (match[i][i]==-1)       
    return -1;
   else continue;
  }
 }
}
 void print(int match[][3])
 {
  int i,j;
  for(i=0;i<3;i++)
  {
   printf("\n");
   for(j=0;j<3;j++)
   {
    printf("%d\t",match[i][j]);
   }
  }
 }