class elem
{
public:
elem();
elem(int aa):a(aa){}
public:
int a;
int getA()
{
return a;
}
};
class elem1
{
public:
elem1();
elem1(int aa):a(aa){}
public:
int a;
int getA()
{
return a;
}
friend bool operator < (const elem1 &e1,const elem1 &e2)//只能重载<
{
return e1.a <e2.a;//大顶堆是<;小顶堆是>
}
};
class Scorer
{
public:
bool operator ()(const elem &e1,const elem &e2)
{
return e1.a<e2.a;
}
};
bool Cmp(const elem &e1,const elem &e2)
{
return e1.a <e2.a;
}
int main()
{
vector<elem> ve;
ve.push_back(elem(5));
ve.push_back(elem(6));
ve.push_back(elem(7));
ve.push_back(elem(1));
ve.push_back(elem(0));
ve.push_back(elem(19));
ve.push_back(elem(60));
ve.push_back(elem(61));
ve.push_back(elem(2));
ve.push_back(elem(68));
ve.push_back(elem(9));
list<elem> le;
le.push_back(elem(5));
le.push_back(elem(6));
le.push_back(elem(7));
le.push_back(elem(1));
le.push_back(elem(0));
le.push_back(elem(19));
le.push_back(elem(6));
priority_queue<int,vector<int>,less<int> > pq;//大顶堆//优先队列如果用仿函数的形式,必须有三个参数
pq.push(5);
pq.push(6);
pq.push(1);
pq.push(2);
pq.push(9);
/*while (!pq.empty())
{
int t = pq.top();
cout<<t<<" ";
pq.pop();
}*/
priority_queue<elem,vector<elem>,Scorer > q;//1.自定义仿函数,也要有三个参数
q.push(5);
q.push(6);
q.push(1);
q.push(2);
q.push(9);
priority_queue<elem1> q1;//2.
q1.push(5);
q1.push(6);
q1.push(1);
q1.push(2);
q1.push(9);
set<int,less<int> > s;//从小到大
s.insert(5);
s.insert(6);
s.insert(1);
s.insert(3);
s.insert(0);
set<elem,Scorer> s1;
s1.insert(5);
s1.insert(6);
s1.insert(1);
s1.insert(3);
s1.insert(0);
set<elem,Scorer >::iterator it;
for (it = s1.begin();it!=s1.end();++it)
{
cout<<it->getA()<<" ";
}
/*while(!q1.empty())
{
elem1 e = q1.top();
cout<<e.getA()<<" ";
q1.pop();
}*/
int array[] = {5,6,7,1,0,19,6};
sort(array,array+7,greater<int>());//less<int>() 从小到大//说明greater,less和Scorer一样都是类,而Cmp是函数;所以vector还是用Cmp形式的函数比较方便
/*for (int i=0;i<7;++i)
{
cout<<array[i]<<" ";
}
cout<<endl;*/
//sort(ve.begin(),ve.end(),Scorer());//sort(ve.begin(),ve.end(),Cmp);
//partial_sort(ve.begin(),ve.begin()+3,ve.end(),Cmp);//对前三个排序
nth_element(ve.begin(),ve.begin()+3,ve.end(),Cmp);//保证前三个最小,前三个不排序
//sort(le.begin(),le.end(),Cmp);
le.sort(Scorer());//Cmp//list的排序是要移动其内部指针的,所以只能用其内部的sort,而不能用通用的sort//也不能用nth_elements之类的排序
/*vector<elem>::iterator it;
for (it = ve.begin();it!=ve.end();++it)
{
cout<<it->getA()<<" ";
}*/
cout<<endl;
}
stl中各种容器的自定义比较函数的方法,vector,list,set相类似,要定义一个比较类,类里面有比较成员函数 bool operator ()(const,const),并且return a<b 是从小到大排序
priority_queue有些不同,主要表现在return a<b是大顶堆
所有的共同之处是,都可以通过定义一个比较类实现排序