marci@866: // -*- c++ -*-
marci@866: 
marci@866: // Use a DIMACS max flow file as stdin.
marci@866: // sub_graph_wrapper_demo < dimacs_max_flow_file
marci@871: // This program computes a maximum number of edge-disjoint shortest paths
marci@869: // between s and t.
marci@866: 
marci@866: #include <iostream>
marci@866: #include <fstream>
marci@866: 
marci@866: #include <hugo/smart_graph.h>
marci@866: #include <hugo/dijkstra.h>
marci@866: #include <hugo/maps.h>
marci@866: #include <hugo/graph_wrapper.h>
marci@866: #include <hugo/dimacs.h>
marci@866: #include <hugo/preflow.h>
marci@888: #include <hugo/tight_edge_filter_map.h>
marci@866: 
marci@866: using namespace hugo;
marci@866: 
marci@866: using std::cout;
marci@866: using std::endl;
marci@866: 
marci@866: int main()
marci@866: {    
marci@866:   typedef SmartGraph Graph;
marci@866: 
marci@866:   typedef Graph::Edge Edge;
marci@866:   typedef Graph::Node Node;
marci@866:   typedef Graph::EdgeIt EdgeIt;
marci@866:   typedef Graph::NodeIt NodeIt;
marci@866:   typedef Graph::EdgeMap<int> LengthMap;
marci@866: 
marci@866:   Graph g;
marci@866:   Node s, t;
marci@866:   LengthMap length(g);
marci@866: 
marci@866:   readDimacs(std::cin, g, length, s, t);
marci@866: 
marci@866:   cout << "edges with lengths (of form tail--length->head): " << endl;
marci@866:   for(EdgeIt e(g); e!=INVALID; ++e) 
marci@866:     cout << " " << g.id(g.tail(e)) << "--" 
marci@866: 	 << length[e] << "->" << g.id(g.head(e)) << endl;
marci@866: 
marci@866:   cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;
marci@866: 
marci@866:   typedef Dijkstra<Graph, LengthMap> Dijkstra;
marci@866:   Dijkstra dijkstra(g, length);
marci@866:   dijkstra.run(s);
marci@866: 
marci@869:   // This map returns true exactly for those edges which are 
marci@869:   // tight w.r.t the length funcion and the potential 
marci@869:   // given by the dijkstra algorithm.
marci@866:   typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap> 
marci@866:     TightEdgeFilter;
marci@866:   TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);
marci@866: 
marci@866:   ConstMap<Node, bool> const_true_map(true);
marci@869:   // This graph contains exaclty the tight edges.
marci@866:   typedef SubGraphWrapper<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
marci@866:   SubGW gw(g, const_true_map, tight_edge_filter);
marci@866: 
marci@866:   ConstMap<Edge, int> const_1_map(1);
marci@866:   Graph::EdgeMap<int> flow(g, 0);
marci@869:   // Max flow between s and t in the graph of tight edges.
marci@866:   Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> > 
marci@866:     preflow(gw, s, t, const_1_map, flow);
marci@866:   preflow.run();
marci@866: 
marci@866:   cout << "edges of the maximum number of edge-disjoint shortest s-t paths: " 
marci@866:        << endl;
marci@866:   for(EdgeIt e(g); e!=INVALID; ++e) 
marci@866:     if (flow[e])
marci@866:       cout << " " << g.id(g.tail(e)) << "--" 
marci@866: 	   << length[e] << "->" << g.id(g.head(e)) << endl;
marci@866: 
marci@866:   return 0;
marci@866: }