348. Design Tic-Tac-Toe.java

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

// You may assume the following rules:

// A move is guaranteed to be valid and is placed on an empty block.
// Once a winning condition is reached, no more moves is allowed.
// 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?



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

    /** Initialize your data structure here. */
    public TicTacToe(int n) {
        rows = new int[n];
        cols = new int[n];
        size = 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;
        }
        
        if(Math.abs(cols[col]) == size ||
            Math.abs(rows[row]) == size ||
            Math.abs(diagonal) == size ||
            Math.abs(antiDiagonal) == size) {
                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);
 */