demo/sub_graph_adaptor_demo.cc
author ladanyi
Tue, 12 Jul 2005 13:36:01 +0000
changeset 1545 e8378402f97e
parent 1435 8e85e6bbefdf
child 1560 01707a8a4ca6
permissions -rw-r--r--
Added the individual png files to EXTRA_DIST instead of the icons directory. This way the .svn directories do not get in the tarball. An alternative solution would be to delete these in a dist-hook target.
     1 // -*- c++ -*-
     2 
     3 // Use a DIMACS max flow file as stdin.
     4 // sub_graph_adaptor_demo < dimacs_max_flow_file
     5 // This program computes a maximum number of edge-disjoint shortest paths
     6 // between s and t.
     7 
     8 #include <iostream>
     9 #include <fstream>
    10 
    11 #include <lemon/smart_graph.h>
    12 #include <lemon/dijkstra.h>
    13 #include <lemon/maps.h>
    14 #include <lemon/graph_adaptor.h>
    15 #include <lemon/dimacs.h>
    16 #include <lemon/preflow.h>
    17 #include <tight_edge_filter_map.h>
    18 
    19 using namespace lemon;
    20 
    21 using std::cout;
    22 using std::endl;
    23 
    24 int main()
    25 {    
    26   typedef SmartGraph Graph;
    27 
    28   typedef Graph::Edge Edge;
    29   typedef Graph::Node Node;
    30   typedef Graph::EdgeIt EdgeIt;
    31   typedef Graph::NodeIt NodeIt;
    32   typedef Graph::EdgeMap<int> LengthMap;
    33 
    34   Graph g;
    35   Node s, t;
    36   LengthMap length(g);
    37 
    38   readDimacs(std::cin, g, length, s, t);
    39 
    40   cout << "edges with lengths (of form id, source--length->target): " << endl;
    41   for(EdgeIt e(g); e!=INVALID; ++e) 
    42     cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--" 
    43 	 << length[e] << "->" << g.id(g.target(e)) << endl;
    44 
    45   cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;
    46 
    47   typedef Dijkstra<Graph, LengthMap> Dijkstra;
    48   Dijkstra dijkstra(g, length);
    49   dijkstra.run(s);
    50 
    51   // This map returns true exactly for those edges which are 
    52   // tight w.r.t the length funcion and the potential 
    53   // given by the dijkstra algorithm.
    54   typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap> 
    55     TightEdgeFilter;
    56   TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);
    57 
    58 //  ConstMap<Node, bool> const_true_map(true);
    59   // This graph contains exaclty the tight edges.
    60 // typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
    61   typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;
    62   SubGW gw(g, tight_edge_filter);
    63 
    64   ConstMap<Edge, int> const_1_map(1);
    65   Graph::EdgeMap<int> flow(g, 0);
    66   // Max flow between s and t in the graph of tight edges.
    67   Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> > 
    68     preflow(gw, s, t, const_1_map, flow);
    69   preflow.run();
    70 
    71   cout << "maximum number of edge-disjoint shortest paths: " 
    72        << preflow.flowValue() << endl;
    73   cout << "edges of the maximum number of edge-disjoint shortest s-t paths: " 
    74        << endl;
    75   for(EdgeIt e(g); e!=INVALID; ++e) 
    76     if (flow[e])
    77       cout << " " << g.id(e) << ", "
    78 	   << g.id(g.source(e)) << "--" 
    79 	   << length[e] << "->" << g.id(g.target(e)) << endl;
    80 }