Replace flush in contract with in-place renumbering

include/contractor/graph_contractor.hpp

@@ -163,13 +163,6 @@ class GraphContractor
             }
         }
         graph = ContractorGraph{};
-        orig_node_id_from_new_node_id_map.clear();
-        orig_node_id_from_new_node_id_map.shrink_to_fit();
-
-        BOOST_ASSERT(0 == orig_node_id_from_new_node_id_map.capacity());
-
-        edges.append(external_edge_list.begin(), external_edge_list.end());
-        external_edge_list.clear();
 
         // sort and remove duplicates
         tbb::parallel_sort(edges.begin(), edges.end());
@@ -408,7 +401,6 @@ class GraphContractor
     bool Bias(const NodeID a, const NodeID b) const;
 
     ContractorGraph graph;
-    ExternalVector<QueryEdge> external_edge_list;
     std::vector<NodeID> orig_node_id_from_new_node_id_map;
     std::vector<float> node_levels;
 

include/util/dynamic_graph.hpp

@@ -351,17 +351,25 @@ template <typename EdgeDataT> class DynamicGraph
                 edge_list[edge].target = old_to_new_node[edge_list[edge].target];
                 old_to_new_edge[edge] = new_edge_index++;
             }
-            // and all adjacent empty edges
-            for (auto edge = EndEdges(node); edge < number_of_edges && isDummy(edge); edge++)
+            node_array[node].first_edge = new_first_edge;
+        }
+        auto number_of_valid_edges = new_edge_index;
+
+        // move all dummy edges to the end of the renumbered range
+        for (auto edge : util::irange<NodeID>(0, edge_list.size()))
+        {
+            if (old_to_new_edge[edge] == SPECIAL_EDGEID)
             {
+                BOOST_ASSERT(isDummy(edge));
                 old_to_new_edge[edge] = new_edge_index++;
             }
-            node_array[node].first_edge = new_first_edge;
         }
         BOOST_ASSERT(std::find(old_to_new_edge.begin(), old_to_new_edge.end(), SPECIAL_EDGEID) ==
                      old_to_new_edge.end());
-
         util::inplacePermutation(edge_list.begin(), edge_list.end(), old_to_new_edge);
+        // Remove useless dummy nodes at the end
+        edge_list.resize(number_of_valid_edges);
+        number_of_edges = number_of_valid_edges;
     }
 
   protected: