组合模式（C++）

#include <iostream>
#include <string>
#include <vector>
using namespace std;

class City//城市的基类
{
protected:
    string m_str;
public:
    City(string str):m_str(str){}
    virtual ~City(){}
    virtual void add(City* city){}
    virtual void display(int dep){}
};

class SpecifiedCity : public City //具体城市
{
private:
    vector<City*> m_list_city;
public:
    SpecifiedCity(string str):City(str){}
    ~SpecifiedCity(){}
    void add(City* city)
    {
        m_list_city.push_back(city);
    }
    void display(int dep)
    {
        for(int i=0; i<dep; i++)
        {
            cout<<"*";
        }
        cout<<m_str<<endl;
        vector<City*>::iterator iter;
        for(iter = m_list_city.begin(); iter != m_list_city.end(); iter++)
        {
            (*iter)->display(dep+2);//此处+2完全是为了表示树形结构，并无其他含义
        }
    }
};

class EducationBureau : public City //教育部
{
public:
    EducationBureau(string str):City(str){}
    virtual ~EducationBureau(){}
    void display(int dep)
    {
        for(int i=0; i<dep; i++)
        {
            cout<<"*";
        }
        cout<<m_str<<endl;
    }
};

class SupervisionBureau : public City//监察部
{
public:
    SupervisionBureau(string str):City(str){}
    virtual ~SupervisionBureau(){}
    void display(int dep)
    {
        for(int i=0; i<dep; i++)
        {
            cout<<"*";
        }
        cout<<m_str<<endl;
    }
};

int main(int argc, char** argv)
{
    City *pRoot =new SpecifiedCity("孝感市");
    City* pLeafA = new EducationBureau("教育部门");
    City* pLeafB = new SupervisionBureau("监察部门");
    pRoot->add(pLeafA);
    pRoot->add(pLeafB);
    pRoot->display(1);

    City *pRootA = new SpecifiedCity("大悟县");
    City* pLeafC = new EducationBureau("教育部门");
    City* pLeafD = new SupervisionBureau("监察部门");
    pRootA->add(pLeafC);
    pRootA->add(pLeafD);
    pRootA->display(4);

    City *pRootB = new SpecifiedCity("红安县");
    City* pLeafE = new EducationBureau("教育部门");
    City* pLeafF = new SupervisionBureau("监察部门");
    pRootB->add(pLeafE);
    pRootB->add(pLeafF);
    pRootB->display(4);

    delete pRoot; delete pLeafA; pLeafB;
    delete pRootA; delete pLeafC; pLeafD;
    delete pRootB; delete pLeafE; pLeafF;

    return 0;
}