undirected-graph-matrix.cpp

/* 
  Adjacency Matrix Representation
*/
// undirected dense graph (with lesser nodes eg N = 1e3)
int adj_matrix[N][N];

int main(){
  int num_nodes, num_edges;
  cin >> num_nodes >> num_edges;
  for(int i = 0, u, v; i < num_edges; ++i){
    // take nodes between which we have an edge
    cin >> u >> v;
    // undirected so we mark both (u, v) and (v, u) as 1
    adj_matrix[u][v] = 1;
    adj_matrix[v][u] = 1;
  }
  // do something with the graph
}