1、B站视频链接：A15 堆 堆排序_哔哩哔哩_bilibili

题目链接：【模板】堆 - 洛谷

#include <iostream>
using namespace std;
int a[1000010],cnt;
void up(int u){ //上浮if(u/2 && a[u/2]>a[u]) swap(a[u],a[u/2]), up(u/2);
}
void down(int u){ //下沉int v=u;if(u*2<=cnt && a[u*2]<a[v]) v=u*2;if(u*2+1<=cnt && a[u*2+1]<a[v]) v=u*2+1;if(u!=v) swap(a[u],a[v]), down(v);
}
void push(int x){ //压入a[++cnt]=x;up(cnt); 
}
void pop(){ //删除a[1]=a[cnt--];down(1);
}
int main(){int n; scanf("%d",&n); //操作次数while(n--){int op,x; scanf("%d",&op);if(op==1) scanf("%d",&x), push(x);else if(op==2) printf("%d\n",a[1]);else pop();}return 0;
}

2、STL大法好

#include <bits/stdc++.h>
using namespace std;
priority_queue<int,vector<int>,greater<int>> q;
//小根堆 
int main(){int n;cin>>n;while(n--){int op,x;cin>>op;if(op==1){cin>>x;q.push(x);}else if(op==2){cout<<q.top()<<endl;}else{q.pop();}}return 0;
}