athos@1583: /* -*- C++ -*-
athos@1583:  *
alpar@1956:  * This file is a part of LEMON, a generic C++ optimization library
alpar@1956:  *
alpar@2553:  * Copyright (C) 2003-2008
alpar@1956:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
athos@1583:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
athos@1583:  *
athos@1583:  * Permission to use, modify and distribute this software is granted
athos@1583:  * provided that this copyright notice appears in all copies. For
athos@1583:  * precise terms see the accompanying LICENSE file.
athos@1583:  *
athos@1583:  * This software is provided "AS IS" with no warranty of any kind,
athos@1583:  * express or implied, and with no claim as to its suitability for any
athos@1583:  * purpose.
athos@1583:  *
athos@1583:  */
athos@1583: 
athos@1583: ///\ingroup demos
athos@1583: ///\file
athos@1583: ///\brief Computing maximum number of edge-disjoint shortest paths
athos@1583: ///
athos@1583: /// This program computes a maximum number of edge-disjoint shortest paths
athos@1583: /// between nodes \c s and \c t.
alpar@1641: ///
alpar@1641: /// \include sub_graph_adaptor_demo.cc
marci@866: 
athos@1560: // Use a DIMACS max flow file as input.
alpar@1401: // sub_graph_adaptor_demo < dimacs_max_flow_file
athos@1583: // Modified to eat lemon graph format! 
athos@1583: 
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>
ladanyi@2013: #include "tight_edge_filter_map.h"
marci@866: 
athos@1583: #include <lemon/graph_reader.h>
athos@1577: 
athos@1577: 
alpar@921: using namespace lemon;
marci@866: 
marci@866: using std::cout;
marci@866: using std::endl;
marci@866: 
athos@1560: int main(int argc, char *argv[]) 
athos@1560: {
athos@1560:   if(argc<2)
athos@1560:   {
athos@1583:       std::cerr << "USAGE: sub_graph_adaptor_demo input_file.lgf" << std::endl;
athos@1583:       std::cerr << "The file 'input_file.lgf' has to contain a max flow "
athos@1583: 		<< "instance in \n LEMON format "
athos@1583: 		<< "(e.g. sub_gad_input.lgf is such a file)." 
athos@1583: 		<< std::endl;
athos@1560:       return 0;
athos@1560:   }
athos@1560: 
athos@1560: 
athos@1560:   //input stream to read the graph from
athos@1560:   std::ifstream is(argv[1]);
athos@1560: 
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: 
athos@1583:   //readDimacs(is, g, length, s, t);
marci@866: 
athos@1577: 
athos@1583:   GraphReader<SmartGraph> reader(is,g);
athos@1583:   reader.readNode("source",s).readNode("target",t)
athos@1583:     .readEdgeMap("length",length).run();
athos@1577: 
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@869:   // Max flow between s and t in the graph of tight edges.
deba@2514:   Preflow<SubGW, ConstMap<Edge, int> > preflow(gw, const_1_map, s, t);
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) 
deba@2514:     if (preflow.flow(e) != 0)
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: }