题解 | 【模板】序列操作

#include <bits/stdc++.h>
#include <vector>
using namespace std;

int main(){
    int q,n,x,i;
    vector<int> arr;
    cin>>q;
    while(q--){
        cin>>n;
        switch(n){
            case 1: 
                cin>>x;
                arr.push_back(x);
                break;
            case 2:
                arr.pop_back();
                break;
            case 3:
                cin>>i;
                cout<<arr[i]<<endl;
                break;
            case 4:
                cin>>i>>x;
                arr.insert(arr.begin()+i+1,x);
                break;
            case 5:
                sort(arr.begin(),arr.end());
                break;
            case 6:
                sort(arr.begin(),arr.end(),[](int a,int b){
                    return a>b;
                });
                break;
            case 7:
                cout<<arr.size()<<endl;
                break;
            case 8:
                for(const auto&num : arr) cout<<num<<' ';
                cout<<endl;
                break;
        }
    }
}