weighted graph c++

//code  by Soumyadeep Ghosh
//insta : @soumyadepp
//linked in: https://www.linkedin.com/in/soumyadeep-ghosh-90a1951b6/

#include <bits/stdc++.h>
using namespace std;

//undirected weighted graph

class WeightedGraph
{
  vector< pair<int,int> >*adjacency_list;
  int vertices;
  public:
  WeightedGraph(int n)
  {
    vertices=n;
    adjacency_list=new vector< pair<int,int> >[n];
  }
  void add_edge(int v1,int v2,int wt);
  void display_graph();
};

int main()
{
  //graph of five vertices
  WeightedGraph wg1(5);
  //adding edges
  wg1.add_edge(0,1,10);
  wg1.add_edge(1,2,20);
  wg1.add_edge(2,3,30);
  wg1.add_edge(1,3,40);
  wg1.add_edge(2,4,100);
  wg1.add_edge(4,0,10);
  //displaying the graph
  wg1.display_graph();
  return 0;
}
//function definitions

void WeightedGraph::add_edge(int v1,int v2,int wt)
{
  /*push the other vertex into the adjacency list of the given vertex
  and vice versa. If it would have been a directed graph,
  only the first line would be enough
  */
  adjacency_list[v1].push_back(make_pair(v2,wt));
  adjacency_list[v2].push_back(make_pair(v1,wt));
}

void WeightedGraph::display_graph()
{
  int a,b;
  //first loop to traverse across vertices
  for(int i=0;i<vertices;i++)
  {
      cout<<"Adjacency list of vertex "<<i<<endl;
    //second loop to traverse across the adjacency list of some vertex i
    for(auto it=adjacency_list[i].begin();it!=adjacency_list[i].end();it++)
    {
      //set a as the vertex number and b as the weight
      a=it->first;
      b=it->second;
      cout<<"Vertex : "<<a<<" Weight : "<<b<<endl;
    }
    cout<<endl;
  }
}

//thank you!