Define one simple concrete subclass of the MoveStrategy class, say RandomStrategy. Make sure that the overriding pickPlace() method returns an empty place. Submit your source code along with sample test runs.

abstract class MoveStrategy {

protected $board;

function __construct(Board $board = null) {

$this->board = $board;

}

abstract function pickPlace();

function toJson() {

return array(name => get_class($this));

}

static function fromJson() {

$strategy = new static();

return $strategy;

}

}