why dislikes?

at least like that

std::cout << "graph";

vector<int> edges[200005]; // 200005 is max node amount

int main{
  int n,m; //n node amount, m edge amount
  cin>>n>>m;
  while (m--){ //repeat m times
    int a,b;
    cin>>a>>b;
    edges[a].push_back(b); //b shares an edge with a
    edges[b].push_back(a); //a shares an edge with b
  }
}

A simple implemetation of a graph(unweigthted,undirectional)

I am a beginner too. I recommend you use usaco guide to learn graph and do some practice problems.

Learn dfs,bfs,dijkstra and solve CSES graph section.

why