c++ – Passing array of vector of pairs by reference

I am trying to pass array of vector by reference as defined here.

Here is how I am trying :

     main()
        {
        
            vector<pair<int, int> > adj[V];
            addEdge(adj, 1, 2, 30);

            ..................
            printGraph(adj, V);
    
        }
    
    void addEdge(vector <pair<int, int> > (&adj) [5], int u,
                                        int v, int wt)
    {
        adj[u].push_back(make_pair(v, wt));
        adj[v].push_back(make_pair(u, wt));
    }

But getting compile time errors? What did I miss?

On the followup note ,can I avoid specifying “5” as a array size in argument of function and keep it blank?