composite in C++

```
#include <vector>
#include <iostream> 
#include <algorithm> 
#include <functional> 
using namespace std;
 
class Graphic {
public:
  virtual void draw() const = 0;
  virtual void add(Graphic *g) {}
};
 
class Line : public Graphic {
public:
  void draw() const {
    cout << "Line draw()\n";
  }
};

class Rectangle : public Graphic {
public:
  void draw() const {
    cout << "Rectangle draw() \n";
  }
};

// Composite
class Picture : public Graphic {
public:
  void draw() const {
    for_each(gList.begin(), gList.end(), mem_fn(&Graphic::draw));
  }
 
  void add(Graphic *graphic) {
    gList.push_back(graphic);
  }
 
private:
  vector<Graphic*> gList;
};
 
int main()
{
  Line line;
  line.draw();
  
  Rectangle rect;
  rect.draw();

  Picture pic;
  pic.add(&line);
  pic.add(&rect);
  pic.add(&rect);
  pic.draw();

  return 0;
}
```
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