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?

思路：用rows，cols数组去记录，1 player1， -1 player2. diagnoal antidiagonal记录 对角线，i == j, diagonal += add, row + col == n  -1, 这点归纳总结即可得公式，antidiagonal += add

class TicTacToe {
    private int n;
    private int diagnoal;
    private int antidiagnoal;
    private int[] rows;
    private int[] cols;
    public TicTacToe(int n) {
        this.n = n;
        this.diagnoal = 0;
        this.antidiagnoal = 0;
        this.rows = new int[n];
        this.cols = new int[n];
    }
    
    public int move(int row, int col, int player) {
        int toadd = player == 1 ? 1 : -1;
        rows[row] += toadd;
        cols[col] += toadd;
        
        if(row == col) {
            diagnoal += toadd;
        }
        if(row + col == n - 1) {
            antidiagnoal += toadd;
        }
        if(Math.abs(rows[row]) == n ||
           Math.abs(cols[col]) == n ||
           Math.abs(diagnoal) == n ||
           Math.abs(antidiagnoal) == n ) {
            return player;
        }
        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);
 */