class ShapeFactory {
public:
    static Shape* createShape(const string& type) {
        if (type == "Circle")
            return new Circle;
        else if (type == "Rectangle")
            return new Rectangle;
        else
            throw runtime_error("Unknown shape type");
    }
};

int main() {
    Shape* circle = ShapeFactory::createShape("Circle");
    Shape* rectangle = ShapeFactory::createShape("Rectangle");
    // ... 使用 circle 和 rectangle 对象
    delete circle;
    delete rectangle;
    return 0;
}