trjhtr

My aim to implement adjacency list correctly. After takin help from here, I have implemented it. I have tried to implement it here, but it was suggested that it is most likely adjacency matrix. Help me to improve my code. Should I add any other function for DFS.

#include <iostream>
#include <vector>

class Graph

 int vertex_count;
 enum Color WHITE, GRAY, BLACK;

 struct Vertex
 
 int id;
 Color color;
 Vertex(int _id) : id(_id),
 color(Color::WHITE)
 
 ;

 struct Adj_list_node
 
 int dest_id;
 Adj_list_node * next;
 Adj_list_node(int _dest_id) : dest_id(_dest_id),
 next (nullptr)
 
 ;

 struct Adj_list
 
 Adj_list_node *head;
 ;
 std::vector<Vertex> vertices;
 std::vector<Adj_list> adjacent;
public:
 Graph(int);
 void add_edge(int, int);
 void depth_first_search();

private:
 void depth_first_search_visit(int);
;

Graph::Graph(int v)

 vertex_count = v;
 adjacent.resize(vertex_count);

 for (int i = 0; i < vertex_count; i++)
 
 vertices.push_back( Vertex(i) );
 adjacent[i].head = nullptr;
 


void Graph::depth_first_search()

 for (const auto& u: vertices)
 
 if (vertices[u.id].color == WHITE)
 
 depth_first_search_visit(u.id);
 
 


void Graph::depth_first_search_visit(int u)

 vertices[u].color = GRAY;
 std::cout << vertices[u].id <<" ";
 const auto& v = adjacent[u].head;
 if (vertices[v->dest_id].color == WHITE)
 
 depth_first_search_visit(v->dest_id);
 
 vertices[u].color = BLACK;


void Graph::add_edge(int src, int dest)

 Adj_list_node *node = new Adj_list_node(dest);
 if (adjacent[src].head == nullptr)
 
 adjacent[src].head = node;
 
 else
 
 Adj_list_node *tmp = adjacent[src].head;
 while (tmp->next != nullptr)
 tmp = tmp->next;

 tmp->next = node;
 

 //undirected graph
 node = new Adj_list_node(src);
 if (adjacent[dest].head == nullptr)
 
 adjacent[dest].head = node;
 
 else
 
 Adj_list_node *tmp = adjacent[dest].head;
 while (tmp->next != nullptr)
 tmp = tmp->next;

 tmp->next = node;
 


int main()

 Graph grp(4);
 grp.add_edge(0, 1);
 grp.add_edge(1, 2);
 grp.add_edge(2, 3);
 grp.add_edge(2, 1);
 grp.add_edge(0, 3);
 grp.depth_first_search();
 std::cout << "n";