code: static int[] verticesInOrder(final int[] rank) {
          int[] vs = new int[rank.length];
          for (int v = 0; v < rank.length; v++)
              vs[rank[v]] = v;
          return vs;
      }
docs: Using the pre-computed rank, get the vertices in order.
  
  @param rank see {@link #rank(int[][])}
  @return vertices in order