Rice and chess

ricechess.js

function rice_chessboard ( A ) {
    return checkPath(A[0][0], 0, 0, A)
}

function checkPath(val, x, y, board){
    if(board[x + 1] && board[x][y+1]){    //If there is room
        var possibility1 = checkPath(val + board[x][y+1], x, (y+1), board);
        var possibility2 = checkPath(val + board[x+1][y], (x+1), y, board);
        
        return possibility1 > possibility2 ? possibility1 : possibility2;
       
    } else if (board[x + 1]){
        return checkPath(val + board[x+1][y], (x+1), y, board);
    } else if (board[x][y+1]){
        return checkPath(val + board[x][y+1], x, (y+1), board);
    } else {
        return val;
    }
}