bool isConnected(List* G, int n){
	
	if(n < 2)
	{
		return true;
	}
	bool* M = new bool[n];
	for(int i = 0; i < n; i++)
	{
		M[i] = false; //none of the nodes have been visited
	}
	int v0 = 0;
	visit(G,M,v0);
	//if there are nodes that were not visited
	//return false
	for(int i = 0; i < n; i++)
	{
		if(!M[i])
		{
			delete[] M;
			return false;
		}
	}
	delete[] M
	return true;
}

void visit(List* G, bool* M, int v){
	//take vertex v, mark it, and then take all it's neighbours marking and visiting them
	M[v] = true;
	for(List p = G[v]; p != nullptr; p = p->next)
	{
		int u = p->vertex;
		if(!M[u])
		{
			visit(G,M,u);
		}
	}
}