Make InertialFlow a function

include/partition/inertial_flow.hpp

@@ -4,42 +4,15 @@
 #include "partition/dinic_max_flow.hpp"
 #include "partition/graph_view.hpp"
 
-#include <unordered_set>
-#include <vector>
-
 namespace osrm
 {
 namespace partition
 {
 
-class InertialFlow
-{
-  public:
-    InertialFlow(const GraphView &view);
-
-    DinicMaxFlow::MinCut ComputePartition(const std::size_t num_slopes,
-                                          const double balance,
-                                          const double source_sink_rate);
-
-  private:
-    // Spatially ordered sources and sink ids.
-    // The node ids refer to nodes in the GraphView.
-    struct SpatialOrder
-    {
-        std::unordered_set<NodeID> sources;
-        std::unordered_set<NodeID> sinks;
-    };
-
-    // Creates a spatial order of n * sources "first" and n * sink "last" node ids.
-    // The slope determines the spatial order for sorting node coordinates.
-    SpatialOrder MakeSpatialOrder(double ratio, double slope) const;
-
-    // Makes n cuts with different spatial orders and returns the best.
-    DinicMaxFlow::MinCut BestMinCut(std::size_t n, double ratio, double balance) const;
-
-    // The subgraph to partition into two parts.
-    const GraphView &view;
-};
+DinicMaxFlow::MinCut computeInertialFlowCut(const GraphView &view,
+                                            const std::size_t num_slopes,
+                                            const double balance,
+                                            const double source_sink_rate);
 
 } // namespace partition
 } // namespace osrm