做题步骤

1. 感觉到这题是模拟题，当然也许你可以直接用优先队列😁
2. 从AI那知道堆是完全二叉树的结构，但是感觉这样模拟好麻烦
3. 看了题解发现别人也是这样做的，然后……

代码：

//  #牛客春招刷题训练营# https://www.nowcoder.com/discuss/726480854079250432
#include <iostream>
#include <vector>
using namespace std;
template<typename T>
class hv_heap{
private:
  int size = 0;
  vector<T> tree;
  void ppush(T x){
    size++;
    tree.emplace_back(x);
    int last = size - 1;
    int root = (last - 1) / 2;
    while(tree[root] < tree[last]){
      swap(tree[root], tree[last]);
      last = root;
      root = (last - 1) / 2;
    }
  }
  bool empty(){
    return size <= 0;
  }
  void down(int root){
    int left = root * 2 + 1,
    right = root * 2 + 2,
    maxroot = root;
    if (left < size && tree[left] > tree[maxroot]) maxroot = left;
    if (right < size && tree[right] > tree[maxroot]) maxroot = right;
    if (maxroot != root){
      swap(tree[maxroot], tree[root]);
      down(maxroot);
    }
  }
  void ppop(){
    if (empty()) cout << "empty\n";
    else {
      cout << tree[0] << "\n";
      tree[0] = tree.back();
      tree.pop_back();
      size--;
      down(0);
    }
  }
public:
  void push(T x){
    ppush(x);
  }
  void top(){
    if (empty()) cout << "empty\n";
    else cout << tree[0] << "\n";
  }
  void pop(){
    ppop();
  }
};
int main() {
  ios_base::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);
  hv_heap<int> heap;
  int n, x;
  cin >> n;
  string s;
  while(n--){
    cin >> s;
    if (s == "push"){
      cin >> x;
      heap.push(x);
    }
    else if (s == "top"){
      heap.top();
    }
    else if (s == "pop"){
      heap.pop();
    }
  }
  return 0;
}
// 64 位输出请用 printf("%lld")