348. Design Tic-Tac-Toe

Design a Tic-tac-toe game that is played between two players on anxngrid.

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) permove()operation?

Thoughts:

1. only need to record row, col, diagonal, antidiagonal: for each move, player1 add 1 and player 2 mimus 1

Code: T: O(n)

class TicTacToe {
public:
    /** Initialize your data structure here. */
    TicTacToe(int n) {
        size = n;
        rows.resize(n, 0);
        cols.resize(n, 0);
        diag = 0, anti_diag = 0;
    }

    /** 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. */
    int move(int row, int col, int player) {
        if(player == 1){
            rows[row]++; cols[col]++;
            if(row == col) diag++;
            if(row + col == size - 1) anti_diag++;
            if(rows[row] == size || cols[col] == size || diag == size || anti_diag == size) return 1;
        }
        else { //player 2
            rows[row] --; cols[col]--;
            if(row == col) diag--;
            if(row + col == size - 1) anti_diag--;
            if(rows[row] == -size || cols[col] == -size || diag == -size || anti_diag == -size) return 2;
        }

        return 0;
    }

private:
    vector<int> rows, cols;
    int diag, anti_diag;
    int size;
};


/**
 * Your TicTacToe object will be instantiated and called as such:
 * TicTacToe obj = new TicTacToe(n);
 * int param_1 = obj.move(row,col,player);
 */

Similar idea in Java

public class TicTacToe {
private int[] rows;
private int[] cols;
private int diagonal;
private int antiDiagonal;

/** Initialize your data structure here. */
public TicTacToe(int n) {
    rows = new int[n];
    cols = new int[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) {
    int toAdd = player == 1 ? 1 : -1;

    rows[row] += toAdd;
    cols[col] += toAdd;
    if (row == col)
    {
        diagonal += toAdd;
    }

    if (col == (cols.length - row - 1))
    {
        antiDiagonal += toAdd;
    }

    int size = rows.length;
    if (Math.abs(rows[row]) == size ||
        Math.abs(cols[col]) == size ||
        Math.abs(diagonal) == size  ||
        Math.abs(antiDiagonal) == size)
        {
        return player;
        }

    return 0;
    }
}