Design Tic-Tac-Toe

Design a Tic-tac-toe game that is played between two players on a n x n grid.

You may assume the following rules:

1. A move is guaranteed to be valid and is placed on an empty block.
2. Once a winning condition is reached, no more moves is allowed.
3. A player who succeeds in placing n of their marks in a horizontal, vertical, or diagonal row wins the game.

Example:

Given n = 3, assume that player 1 is "X" and player 2 is "O" in the board.

TicTacToe toe = new TicTacToe(3);

toe.move(0, 0, 1); -> Returns 0 (no one wins)
|X| | |
| | | |    // Player 1 makes a move at (0, 0).
| | | |

toe.move(0, 2, 2); -> Returns 0 (no one wins)
|X| |O|
| | | |    // Player 2 makes a move at (0, 2).
| | | |

toe.move(2, 2, 1); -> Returns 0 (no one wins)
|X| |O|
| | | |    // Player 1 makes a move at (2, 2).
| | |X|

toe.move(1, 1, 2); -> Returns 0 (no one wins)
|X| |O|
| |O| |    // Player 2 makes a move at (1, 1).
| | |X|

toe.move(2, 0, 1); -> Returns 0 (no one wins)
|X| |O|
| |O| |    // Player 1 makes a move at (2, 0).
|X| |X|

toe.move(1, 0, 2); -> Returns 0 (no one wins)
|X| |O|
|O|O| |    // Player 2 makes a move at (1, 0).
|X| |X|

toe.move(2, 1, 1); -> Returns 1 (player 1 wins)
|X| |O|
|O|O| |    // Player 1 makes a move at (2, 1).
|X|X|X|

Follow up:
Could you do better than O(n2) per move() operation?

Hint:

1. Could you trade extra space such that move() operation can be done in O(1)?
2. You need two arrays: int rows[n], int cols[n], plus two variables: diagonal, anti_diagonal.

3. public class TicTacToe {
       int rows[];
       int cols[];
       int diagonal;
       int antiDiagonal;
       int n;
       
       /** Initialize your data structure here. */
       public TicTacToe(int n) {
           rows = new int[n];
           cols = new int[n];
           for (int i = 0; i < n; i++) {
               rows[i] = cols[i] = 0;
           }
           diagonal = antiDiagonal = 0;
           this.n = n;
       }
       
       /** Player {player} makes a move at ({row}, {col}).
           @param row The row of the board.
           @param col The column of the board.
           @param player The player, can be either 1 or 2.
           @return The current winning condition, can be either:
                   0: No one wins.
                   1: Player 1 wins.
                   2: Player 2 wins. */
       public int move(int row, int col, int player) {
           if (player == 1) {
               if (row == col)
                   diagonal++;
               if (row + col == n - 1)
                   antiDiagonal++;
               rows[row]++;
               cols[col]++;
               
               if (diagonal == n || antiDiagonal == n || rows[row] == n || cols[col] == n) return 1;
           } else {
               if (row == col)
                   diagonal--;
               if (row + col == n - 1)
                   antiDiagonal--;
               rows[row]--;
               cols[col]--;
               
               if (diagonal == -n || antiDiagonal == -n || rows[row] == -n || cols[col] == -n) return 2;
           }
           return 0;
       }
   }
   
   /**
    * Your TicTacToe object will be instantiated and called as such:
    * TicTacToe obj = new TicTacToe(n);
    * int param_1 = obj.move(row,col,player);
    */

4. public class TicTacToe {
       private char[][] board;
       private int N = 0;
       
       /** Initialize your data structure here. */
       public TicTacToe(int n) {
           board = new char[n][n];
           N = n;
       }
       
       /** Player {player} makes a move at ({row}, {col}).
           @param row The row of the board.
           @param col The column of the board.
           @param player The player, can be either 1 or 2.
           @return The current winning condition, can be either:
                   0: No one wins.
                   1: Player 1 wins.
                   2: Player 2 wins. */
       public int move(int row, int col, int player) {
           // check the first player
           if (player == 1) {
               board[row][col] = 'X';
               if (checked(board, 'X')) return 1;
           } else {
               board[row][col] = 'O';
               if (checked(board, 'O')) return 2;
           }
           
           return 0;
       }
       
       private boolean checked(char[][] board, char ch) {
           for (int i = 0; i < N; i++) {
               for (int j = 0; j < N; j++) {
                   if (board[i][j] == ch) {
                       int count1 = 0, count2 = 0, count3 = 0, count4 = 0;
                       // check diagonal
                       if (i == 0 && j == 0) {
                           int m = i, n = j;
                           while (m < N && n < N && board[m][n] == ch) {
                               count1++;
                               m++; n++;
                           }
                       }
                       if (i == 0 && j == N - 1) {
                           int m = i, n = j;
                           while (m < N && n >= 0 && board[m][n] == ch) {
                               count2++;
                               m++; n--;
                           }
                       }
                       if (j == 0) { // check characters in a row
                           int n = j;
                           while (n < N && board[i][n] == ch) {
                               count3++;
                               n++;
                           }
                       }
                       if (i == 0) { // check characters in a column
                           int m = i;
                           while (m < N && board[m][j] == ch) {
                               count4++;
                               m++;
                           }
                       }
                       
                       if (count1 == N || count2 == N || count3 == N || count4 == N) return true;
                   }
               }
           }
           return false;
       }
   }
   
   /**
    * Your TicTacToe object will be instantiated and called as such:
    * TicTacToe obj = new TicTacToe(n);
    * int param_1 = obj.move(row,col,player);
    */