class TicTacToeBoard 
{   
   private String[][] grid;
   
   /**
    * Create a new tic-tac-toe board
    * @param n the size of an n x n board
    */
   public TicTacToeBoard(int n)
   {  grid = new String[n][n];
      // start with the board clear
      clear();
 
   }
 
   /**
    * Find and return the winner of the game.
    * @return the winner of the game, an "X" or an "O"
    */
   public String getWinner()
   {  // check rows for a match
      for (int i = 0; i < grid.length; i++)
      {  
         // check next row if 1st or 2nd are all blanks
         if (grid[i][0].equals("") && i < grid.length-1)
         i++;  
         String p = grid[i][0];
         boolean same = true;
         int j = 1;
         while( j < grid.length && same)
         {
            if (!p.equals(grid[i][j]))
               same = false;
            else
               j++;
         }
 
         if (same) 
            return p;
 
      }
 
      // check columns for a match
       for (int j = 0; j < grid.length; j++)
      {  
        // check next column if 1st or 2nd are all blanks
        if (grid[0][j].equals(" ") && j < grid.length-1)
            j++;  
         String p = grid[j][0];
         boolean same = true;
         int i = 1;
         while( i < grid.length && same)
         {
            if (!p.equals(grid[i][j]))
               same = false;
            else
               i++;
         }
 
         if (same) 
            return p;
      }
 
      // check columns for a match
      // YOU WRITE THIS CODE
 
      // check diagonals
      // YOU WRITE THIS CODE
     
 
 
      return " ";
   }
 
   /**
    * Sets the position for a given row and a given column
    * The cell must be empty and the row and column coordinates must be valid
    * @param i the ith row 
    * @param j the jth column
    * @param s the string to set
    */    
   public void set(int i, int j, String s)
   {  if (0 <= i && i < grid.length && 0 <= j && j < grid[i].length && grid[i][j].equals(" "))
      {
         grid[i][j].equals(s);
      }
   }
 
 
   /**
    * Gets the value in the array for a given row and a given column
    * The  row and column coordinates must be valid
    * @param i the ith row 
    * @param j the jth column 
    * @return the string at the given row and column coordinates
    */    
   public String get(int i, int j)
   {  
 
      return  "s";
   }
 
   /**
    * Clears the board - sets all array elements to the empty string, ( " " )
    */   
   public void clear()
   {  for (int i = 0; i < grid.length; i++)
        {
             grid[i].equals("");
        }
      for(int j = 0; j < grid.length; j++)
        {
            grid[j].equals("");
        }
   }    
 
  /** 
   * Prints the board
   */
   public void printBoard()
   {  
       System.out.println();
        for(int i = 0; i < grid.length; i++)
        {
            for(int j = 0; j < grid.length; j++)
            {
                System.out.print(grid[i][j] + "" );
 
                System.out.println();
            }
        } 
   }
 
}