DesignTicTacToe

gistfile1.txt

package test;

// The key observation is that in order to win Tic-Tac-Toe you must have the entire row or column.

public class DesignTicTacToe {

    class TicTacToe {

        int[] rows;
        int[] cols;

        int d1 = 0; // 正对角线
        int d2 = 0; // 反对角线

        int n;

        /** Initialize your data structure here. */
        public TicTacToe(int n) {
            this.n = 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 p = player == 1 ? 1 : -1; // 关键一步

            rows[row] += p;
            cols[col] += p;

            if (row == col) d1 += p; // 正对角线
            if (row+col+1 == n) d2 += p; // 反对角线

            if (Math.abs(rows[row]) == n || Math.abs(cols[col]) == n || Math.abs(d1) == n || Math.abs(d2) == n) {
                return player;
            }

            return 0;
        }
    }
}