#include<iostream>

#include <set>

using namespace std;

template <class T>

class RuntimeCmp

{

public:

    enum cmp_mode {normal,reverse};

private:

    cmp_mode m_mode;

public:

    RuntimeCmp(cmp_mode m = normal):m_mode(m){};

    bool operator () (const T& t1,const T& t2)

    {

        return m_mode == normal ? t1 < t2 : t1>t2;

    }

    bool operator == (const RuntimeCmp& rc)

    {

        return m_mode = rc.m_mode;

    }

};

typedef std::set<int,RuntimeCmp<int>> IntSet;

int _tmain(int argc, int argv[])

{

    IntSet intSet;

    intSet.insert();

    intSet.insert();

    intSet.insert();

    int aa = ;

} 

set是使用树结构来实现的。