How can I push_back data in a 2d vector of type int

Question

I have a vector and want to store int data in to it at run time can I store the data in a 2D vector in this manner ?

std::vector<std::vector <int>> normal:
    for(i=0;i<10;i++){
        for(j=0;j<20;j++){
            normal[i].push_back(j);
    }
}

Answer 1

Yes, but you also need to push each of the sub-vectors:

std::vector<std::vector<int>> normal;
for(int i=0; i<10; i++)
{
    normal.push_back(std::vector<int>());
    for(int j=0; j<20; j++)
    {    
        normal[i].push_back(j);    
    }
}

Answer 2

create a temporary vector push elements into this temporary vector and then push this temporary vector(v2 in my code) into a 2d vector(v1 in my code).

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

 int main()
 {

    vector<vector<int>> v1;
    vector<int> v2;
    v2.push_back(1);
    v2.push_back(2);
    v2.push_back(13);
    v2.push_back(14);
    v2.push_back(15);

    v1.push_back(v2);
    //i pushed v2 into v1

    int j=0;
    for(int i=0 ; i<5 ;i++)
    {
        cout<<v1[0][i]<<"\t";
    }
  }