更简洁的中位对顶堆写法

#include<bits/stdc++.h>
using namespace std;
template<typename T>
class d_heap
{
	private:
		#define pq priority_queue
		pq<T>big;
		pq<T,vector<T>,greater<T> >small;
		#undef pq
		void ph()//左右平衡 
		{
			if(big.size()<small.size())
				big.push(small.top()),small.pop();
			if(big.size()-small.size()>1)
				small.push(big.top()),big.pop();
		}
	public:
		void push(T x)
		{
			if(small.size() && x>small.top())small.push(x);
			else big.push(x);
			ph();
		}
		T top()
		{
			return big.top();
		}
};
d_heap<int>q;
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		int x;cin>>x;
		q.push(x);
		if(i%2)
			cout<<q.top()<<"\n";
	}
	return 0;
}

vector+二分写法

#include<bits/stdc++.h>
using namespace std;
vector<int>v;
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		int x;cin>>x;
		v.insert(upper_bound(v.begin(),v.end(),x),x);
		if(i%2)
			cout<<v[v.size()/2]<<"\n";
	}
	return 0;
}