How to Insert Elements into 2D Vector in C++?

#include <bits/stdc++.h>
using namespace std;
int main() {
    vector<vector<int>> v = {{1, 2, 3}, 
                            {4, 5, 6}};
  
    // Adding a new row at the end
    v.push_back({7, 8, 9});
  
    // Adding an element to the last row
    v[2].push_back(10);
    for (const auto& i : v) {
        for (int j : i)
            cout << j << " ";
        cout << endl;
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main() {
    vector<vector<int>> v = {{1, 3, 5}, 
                             {7, 9, 11}};
    // Inserting a new row at position 1
    v.insert(v.begin() + 1, {4, 6, 8});
    // Inserting a value into 2nd row at position 2
    v[1].insert(v[1].begin() + 2, 10);
    for (const auto& i : v) {
        for (int j : i)
            cout << j << " ";
        cout << endl;
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main() {
    vector<vector<int>> v = {{1, 3, 5}, 
                             {7, 9, 11}};
    // Emplacing a new row at position 1
    v.emplace(v.begin() + 1, vector<int>{4, 6, 8});
    // Emplacing value into 2nd row at position 2
    v[1].emplace(v[1].begin() + 2, 10);
    for (const auto& i : v) {
        for (int j : i)
            cout << j << " ";
        cout << endl;
    }
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main() {
    vector<vector<int>> v = {{1, 3, 5}, 
                             {7, 9, 11}};
    // Emplacing a new row at the end
    v.emplace_back(vector<int>{4, 6, 8});
    // Emplacing a value in the last row
    v[2].emplace_back(10);
    for (const auto& i : v) {
        for (int j : i)
            cout << j << " ";
        cout << endl;
    }
    return 0;
}