void insert_edge(graphT *g, int x, int y, int w)
{
        edgenodeT *pe, *current, *prev;
        pe = malloc(sizeof(edgenodeT)); // check if NULL
        pe->weight = w;
        pe->y = y;
  pe->next = NULL;
        // YOU MUST MODIFY THIS FUNCTION SO IT WILL KEEP LINK LIST SORTED
        // W.R.T. NEIGHBOR IDs.
  current = g->edges[x];
  if(current == NULL) {
    g->edges[x] = pe;
  } else {
    while(current) {
      if(current->y > pe->y) {
        if(prev == NULL) {
          g->edges[x] = pe;
          pe->next = current;
        } else {
          pe->next = current;
          prev->next = pe;
        }
        break;
      }
      if(current->next == NULL) {
        current->next = pe;
        pe->next = NULL;
        break;
      } else {
        prev = current;
        current = current->next;
      }
    }
  }
        g->degree[x]++;
        g->nedges++;
}