// Graph operation implementation
#include <dgl/graph_op.h>

namespace dgl {

Graph GraphOp::DisjointUnion(std::vector<const Graph*> graphs) {
  Graph rst;
  uint64_t cumsum = 0;
  for (const Graph* gr : graphs) {
    rst.AddVertices(gr->NumVertices());
    for (uint64_t i = 0; i < gr->NumEdges(); ++i) {
      rst.AddEdge(gr->all_edges_src_[i] + cumsum, gr->all_edges_dst_[i] + cumsum);
    }
    cumsum += gr->NumVertices();
  }
  return rst;
}

}  // namespace dgl