Q:

# how to take input in 2d vector in c++

``````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));``````
1
``````myVector[
Vector[0, 4, 2, 5],
Vector[1, 4, 2]
];

/*When you call for myVector.size() it would return 3 and  would return 4.

For the amount of rows (int vectors) in the 2d vector, you can just use myVector.size()

You can run this to see it in actions*/``````
2
``````// Initializing 2D vector "vect" with
// values
vector<vector<int> > vect{ { 1, 2, 3 },
{ 4, 5, 6 },
{ 7, 8, 9 } }; ``````
4
``````std::vector<vector<int>> d;
//std::vector<int> d;
cout<<"Enter the N number of ship and port:"<<endl;
cin>>in;
cout<<"\Enter preference etc..:\n";
for(i=0; i<in; i++){
cout<<"ship"<<i+1<<":"<<' ';
for(j=0; j<in; j++){
cin>>temp;
d[i].push_back(temp);
}
}``````
1
``````std::vector<vector<int>> d;
//std::vector<int> d;
cout<<"Enter the N number of ship and port:"<<endl;
cin>>in;
cout<<"\Enter preference etc..:\n";
for(i=0; i<in; i++){
cout<<"ship"<<i+1<<":"<<' ';
for(j=0; j<in; j++){
cin>>temp;
d.push_back(temp);// I don't know how to push_back here!!
}
}``````
0