pls some send link or explain vectors of vectors

thank you.

# Pls explain vector of vector

vector of vector i.e. "vector<vector > v " is same as 2-d array . The only difference is the representation and style of inserting the element or mostly the same.When we use 2-d array then while inserting the element we first insert in the first row and then in the other rows.Means we insert into array row-wise.Here is the same case.

if you want to insert into a 2-d array then you can do like this :

suppose you want to have a 2-d vector of size n x n .

declaration :

vector<vector > v;

I want to insert like the following :

1 1 1 1 1 …n times

2 2 2 2 2 …n times

. . . . .

. . . . .

n n n n n …n times

Then for this I will do this:

for(int i=1;i<=n;i++)

{

vector temp; // temporary vector

for(int j=1;j<=n;j++) temp.push_back(i); //pushing elements into temp vector column-wise

v.push_back(temp); // push the row vector one by one to make 2-d vector

temp.clear(): // make the vector size 0 by clearing all the elements.

}

so what i am doing here is that i am pushing 1-d vector into a another 2-dimensional vector .

Although everyone have been using different methods.It may be one of them.

Following are the link for vector :

You can search more ! Hope this helps !

Let’s say you want to initialize 2D vector, m*n, with initial value to be 0

we could do this

```
#include<iostream>
int main(){
int m = 2, n = 5;
vector<vector<int>> vec(m, vector<int> (n, 0));
return 0;
}
```

Then to print value you can use vec[i][j] as same as in array.