对顶堆

#include <bits/stdc++.h>
#define int long long
#define ll long long
using namespace std;
signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	priority_queue<ll>a;//大根堆
	priority_queue<ll,vector<ll>,greater<ll>>b;//小根堆
	int n;
	cin>>n;
	for(int i=1;i<=n;i++){
		ll x;
		cin>>x;
		if(b.empty()||x>=b.top()){
			b.push(x);
		}
		else{
			a.push(x);
		}
		int k=(i+1)/2;
		while(b.size()>k){
			a.push(b.top()),b.pop();
		}
		while(b.size()<k){
			b.push(a.top()),a.pop();
		}
		if(i%2==1){
			cout<<b.top()<<endl;
		}
		
	}
	
	return 0;
}