组合模式

using System;
using System.Collections;
using System.Collections.Generic;

public abstract class Graphics
{
    public abstract void Draw();
}

public class Picture:Graphics
{
    protected ArrayList list=new ArrayList();
    public override void Draw()
    {
        foreach(Graphics g in list)
        {
            g.Draw();
        }
    }
    
    public void Add(Graphics g)
    {
        list.Add(g);
    }
    
    public void Remove(Graphics g)
    {
        list.Remove(g);
    }
}
public class Line:Graphics
{
    public override void Draw()
    {
        Console.WriteLine("Line Draw();");
    }
}

public class Circle:Graphics
{
    public override void Draw()
    {
        Console.WriteLine("Circle Draw();");
    }
}

public class Rectangle:Graphics
{
    public override void Draw()
    {
        Console.WriteLine("Rectangle Draw();");
    }
}

public class MyClass
{
    public static void Main()
    {
        Picture myPicture=new Picture();
        myPicture.Add(new Line());
        myPicture.Add(new Circle());
        
        Rectangle myRec=new Rectangle();
        myPicture.Add(myRec);
        
        myPicture.Draw();
        Console.ReadLine();
    }
}

using System;
using System.Collections;
using System.Collections.Generic;

public abstract class Component
{
    protected string name;
    public Component(string name)
    {
        this.name=name;
    }
    public abstract void Display(int depth);
}
public class Composite:Component
{
    private ArrayList children=new ArrayList();
    
    public Composite(string name):base(name)
    {}
    
    public void Add(Component component)
    {
        children.Add(component);
    }
    public void Remove(Component component)
    {
        children.Remove(component);
    }
    
    public override void Display(int depth)
    {
        Console.WriteLine(new String('-',depth)+this.name);
    }
}

public class Leaf:Component
{
    public Leaf(string name):base(name)
    {
        
    }
    public override void Display(int depth)
    {
        Console.WriteLine(new String('-',depth)+this.name);
    }
}

public class MyClass
{
    public static void Main()
    {
        Composite root=new Composite("root");
        root.Add(new Leaf("Leaf A"));
        root.Add(new Leaf("Leaf B"));
        
        Composite comp=new Composite("Composite X");
        comp.Add(new Leaf("Leaf XA"));
        comp.Add(new Leaf("Leaf XB"));
        root.Add(comp);
        root.Add(new Leaf("Leaf C"));
        root.Add(new Leaf("Leaf D"));
        
        Leaf l=new Leaf("Leaf E");
        root.Add(l);
        root.Remove(l);
        
        root.Display(2);
        
        Console.ReadLine();
        
        
    }
}