vector operations in c 2b 2b

1#include <vector>
2
3int main() {
4  std::vector<int> v;
5  v.push_back(10); // v = [10];
6  v.push_back(20); // v = [10, 20];
7  
8  v.pop_back(); // v = [10];
9  v.push_back(30); // v = [10, 30];
10  
11  auto it = v.begin();
12  int x = *it; // x = 10;
13  ++it;
14  int y = *it; // y = 30
15  ++it;
16  bool is_end = it == v.end(); // is_end = true
17  
18  return 0;
19}

1#include <iostream>
2#include<vector>
3#include<algorithm>
4
5using namespace std;
6
7int main()
8{
9    int n;
10    cin>>n;
11    vector<int>vec(n);
12    for(int i=0;i<n;i++)
13    {
14        cin>>vec[i];
15    }
16    cout<<"----------"<<endl;
17    for(int i=0;i<n;i++)
18    {
19      cout<<vec[i]<<" ";
20    }
21    vec.push_back(100);
22    vec.push_back(200);
23    cout<<endl;
24    auto it=vec.begin();
25    vec.insert(it,3,1000);
26    for(vector<int>::iterator it1=vec.begin();it1!=vec.end();it1++)
27    {
28        cout<<*it1<<" ";
29    }
30    cout<<endl;
31    vector<int>vec2;
32    vec2.push_back(15);
33    vec2.push_back(25);
34    vec2.push_back(35);
35    vec.insert(it,vec2.begin(),vec2.end());
36    for(vector<int>::iterator it1=vec.begin();it1!=vec.end();it1++)
37    {
38        cout<<*it1<<" ";
39    }
40    cout<<endl;
41    vec.pop_back();
42    vec.pop_back();
43    for(vector<int>::iterator it1=vec.begin();it1!=vec.end();it1++)
44    {
45        cout<<*it1<<" ";
46    }
47    cout<<endl;
48    int k;
49    cin>>k;
50    cout<<endl;
51    vector<int>::iterator its=vec.begin()+k-1;
52    int s=vec.size();
53    cout<<s<<endl;
54    vec.erase(its);
55    for(vector<int>::iterator it1=vec.begin();it1!=vec.end();it1++)
56    {
57        cout<<*it1<<" ";
58    }
59    
60
61    return 0;
62}
63