auto M = 4; // num of rows
auto N = 3; // num of cols in each row
auto default_value = 1; // default value of all int elements
std::vector<std::vector<int>> matrix(M, std::vector<int>(N, default_value));
vector<vector<int>> vec( n , vector<int> (m, 0));
where: n is number of ROWS,
m is number of COLUMNS
So result will be ( Let n = 2, m = 3 )
[[ 0, 0, 0],
[ 0, 0, 0]]
( 2 x 3 )
#include<vector>
#include<algorithm>
// all the std and main syntax ofcourse.
vector<int> pack = {1,2,3} ;
// To add at the END
pack.push_back(6); // {1,2,3,6}
// OR
// To add at BEGGINING
pack.insert(pack.begin(),6) // {6,1,2,3,}