FindWinneronaTicTacToeGame.java

class Solution {

    public static String checkBoard(char[][] board){

        // check all columns
        for(int j = 0; j < 3; j++){

            int countA = 0;
            int countB = 0;
            for(int i = 0; i < 3; i++){
                if(board[i][j] == 'X') countA ++;
                else if(board[i][j] == 'O') countB ++;
            }

            if(countA == 3) return "A";
            if(countB == 3) return "B";
        }

        // check all rows
        for(int j = 0; j < 3; j++){

            int countA = 0;
            int countB = 0;
            for(int i = 0; i < 3; i++){
                if(board[j][i] == 'X') countA ++;
                else if(board[j][i] == 'O') countB ++;
            }

            if(countA == 3) return "A";
            if(countB == 3) return "B";
        }

        // check diagonal
        if(board[0][0] == 'X' && board[1][1] == 'X' && board[2][2] == 'X') return "A";
        if(board[0][0] == 'O' && board[1][1] == 'O' && board[2][2] == 'O') return "B";

        // check other diagonal
        if(board[2][0] == 'X' && board[1][1] == 'X' && board[0][2] == 'X') return "A";
        if(board[2][0] == 'O' && board[1][1] == 'O' && board[0][2] == 'O') return "B";

        // check for draw
        int c = 0;
        for(int i = 0; i < 3; i++){
            for(int j = 0; j < 3; j++) if(board[i][j] == 'X' || board[i][j] == 'O') c++;
        }

        if(c != 9) return "Pending";

        return "Draw";


    }

    public String tictactoe(int[][] moves) {

        int n = moves.length;
        char[][] board = new char[3][3];
        for(int i = 0; i < 3; i++){
            for(int j = 0; j < 3; j++) board[i][j] = '.';
        }

        // initialize
        for(int i = 0; i < n; i++){
            if(i % 2 == 0){ // => A
                board[moves[i][0]][moves[i][1]] = 'X';
            } else{ // B
                board[moves[i][0]][moves[i][1]] = 'O'; // => O
            }
        }

        return checkBoard(board);

    }
}