nested unique_ptr and stl containers

Question

I have recently read about RAII and have begun using it. I am trying to define graph as adjacency list and allocate the entire DS on heap using unique_ptr. I know that I can define them as stack objects, but I am trying to use unique_ptr's to get used to them.

I am doing the following

unique_ptr to vector  --
                       |-->(unique_ptr)list<edge>
                       |-->(unique_ptr)list<edge>
                       |-->(unique_ptr)list<edge>
                       |-->(unique_ptr)list<edge>

Code:

#include<memory>
#include<vector>
#include<list>
using namespace std;

struct edge {
    int vertex;
    int weight;
};
int vertices = 10;
unique_ptr<vector<unique_ptr<list<struct edge > > > >
    adj_list(new vector<list<struct edge> >(10)); // THIS COMPILES

unique_ptr<vector<unique_ptr<list<struct edge > > > >
    adj_list(new vector<list<struct edge> >(10, new list<edge>())); //THIS GIVES COMPILATION ERROR

Can anyone help me correct this?

EDIT:

I have doubt regarding vector being RAII classes. if I do the following

vector<int> *v;
v = new vector<int> (10);

Do I have to delete the variable v. Or will it automatically free the memory on heap, when it goes out of scope ?

EDIT: using pointer to vector makes the user responsible for memory management.

Answer 1

Your unique_ptrs are unnecessary. Just use the objects themselves:

vector<list<edge>> adj_list;

RAII does not imply smart pointers, it's the other way around. C++ accomodated RAII long before smart pointers.

Answer 2

Look at vector's constructors here. None of them accepts a pointer to the element. So either use vector<list<struct edge>*> or change the call to this:

list<struct edge> emptyList;
... (new vector<list<struct edge> >(10, emptyList));