marci@866: // -*- c++ -*-
marci@866: 
marci@866: // Use a DIMACS max flow file as stdin.
alpar@1401: // sub_graph_adaptor_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: 
alpar@921: #include <lemon/smart_graph.h>
alpar@921: #include <lemon/dijkstra.h>
alpar@921: #include <lemon/maps.h>
alpar@1401: #include <lemon/graph_adaptor.h>
alpar@921: #include <lemon/dimacs.h>
alpar@921: #include <lemon/preflow.h>
marci@931: #include <tight_edge_filter_map.h>
marci@866: 
alpar@921: using namespace lemon;
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: 
alpar@986:   cout << "edges with lengths (of form id, source--length->target): " << endl;
marci@866:   for(EdgeIt e(g); e!=INVALID; ++e) 
alpar@986:     cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--" 
alpar@986: 	 << length[e] << "->" << g.id(g.target(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@932: //  ConstMap<Node, bool> const_true_map(true);
marci@869:   // This graph contains exaclty the tight edges.
alpar@1401: // typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
alpar@1401:   typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;
marci@932:   SubGW gw(g, 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: 
athos@1544:   cout << "maximum number of edge-disjoint shortest paths: " 
marci@931:        << preflow.flowValue() << endl;
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@931:       cout << " " << g.id(e) << ", "
alpar@986: 	   << g.id(g.source(e)) << "--" 
alpar@986: 	   << length[e] << "->" << g.id(g.target(e)) << endl;
marci@866: }