/* -*- C++ -*-

  * demo/lp_maxflow_demo.cc - Part of LEMON, a generic C++ optimization library

  *

  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

  * (Egervary Research Group on Combinatorial Optimization, EGRES).

  *

  * Permission to use, modify and distribute this software is granted

  * provided that this copyright notice appears in all copies. For

  * precise terms see the accompanying LICENSE file.

  *

  * This software is provided "AS IS" with no warranty of any kind,

  * express or implied, and with no claim as to its suitability for any

  * purpose.

  *

  */

 ///\ingroup demos

 ///\file

 ///\brief Computing maximum number of edge-disjoint shortest paths

 ///

 /// This program computes a maximum number of edge-disjoint shortest paths

 /// between nodes \c s and \c t.

 // Use a DIMACS max flow file as input.

 // sub_graph_adaptor_demo < dimacs_max_flow_file

 // Modified to eat lemon graph format! 

 #include <iostream>

 #include <fstream>

 #include <lemon/smart_graph.h>

 #include <lemon/dijkstra.h>

 #include <lemon/maps.h>

 #include <lemon/graph_adaptor.h>

 #include <lemon/dimacs.h>

 #include <lemon/preflow.h>

 #include <tight_edge_filter_map.h>

 #include <lemon/graph_reader.h>

 using namespace lemon;

 using std::cout;

 using std::endl;

 int main(int argc, char *argv[]) 

 {

   if(argc<2)

   {

       std::cerr << "USAGE: sub_graph_adaptor_demo input_file.lgf" << std::endl;

       std::cerr << "The file 'input_file.lgf' has to contain a max flow "

 		<< "instance in \n LEMON format "

 		<< "(e.g. sub_gad_input.lgf is such a file)." 

 		<< std::endl;

       return 0;

   }

   //input stream to read the graph from

   std::ifstream is(argv[1]);

   typedef SmartGraph Graph;

   typedef Graph::Edge Edge;

   typedef Graph::Node Node;

   typedef Graph::EdgeIt EdgeIt;

   typedef Graph::NodeIt NodeIt;

   typedef Graph::EdgeMap<int> LengthMap;

   Graph g;

   Node s, t;

   LengthMap length(g);

   //readDimacs(is, g, length, s, t);

   GraphReader<SmartGraph> reader(is,g);

   reader.readNode("source",s).readNode("target",t)

     .readEdgeMap("length",length).run();

   cout << "edges with lengths (of form id, source--length->target): " << endl;

   for(EdgeIt e(g); e!=INVALID; ++e) 

     cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--" 

 	 << length[e] << "->" << g.id(g.target(e)) << endl;

   cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;

   typedef Dijkstra<Graph, LengthMap> Dijkstra;

   Dijkstra dijkstra(g, length);

   dijkstra.run(s);

   // This map returns true exactly for those edges which are 

   // tight w.r.t the length funcion and the potential 

   // given by the dijkstra algorithm.

   typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap> 

     TightEdgeFilter;

   TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);

 //  ConstMap<Node, bool> const_true_map(true);

   // This graph contains exaclty the tight edges.

 // typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;

   typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;

   SubGW gw(g, tight_edge_filter);

   ConstMap<Edge, int> const_1_map(1);

   Graph::EdgeMap<int> flow(g, 0);

   // Max flow between s and t in the graph of tight edges.

   Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> > 

     preflow(gw, s, t, const_1_map, flow);

   preflow.run();

   cout << "maximum number of edge-disjoint shortest paths: " 

        << preflow.flowValue() << endl;

   cout << "edges of the maximum number of edge-disjoint shortest s-t paths: " 

        << endl;

   for(EdgeIt e(g); e!=INVALID; ++e) 

     if (flow[e])

       cout << " " << g.id(e) << ", "

 	   << g.id(g.source(e)) << "--" 

 	   << length[e] << "->" << g.id(g.target(e)) << endl;

 }