COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/sub_graph_adaptor_demo.cc @ 1571:68ce4302fb0b

Last change on this file since 1571:68ce4302fb0b was 1560:01707a8a4ca6, checked in by athos, 14 years ago

Some demo programs got some interface. Most progress with lp_maxflow_demo.cc, which also got documented.

File size: 2.7 KB
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1// -*- c++ -*-
2
3// Use a DIMACS max flow file as input.
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
19using namespace lemon;
20
21using std::cout;
22using std::endl;
23
24int main(int argc, char *argv[])
25{
26  if(argc<2)
27  {
28      std::cerr << "USAGE: sub_graph_adaptor_demo <input_file.dim>" << std::endl;
29      std::cerr << "The file 'input_file.dim' has to contain a max flow instance in DIMACS format (e.g. sub_graph_adaptor_demo.dim is such a file)." << std::endl;
30      return 0;
31  }
32
33
34  //input stream to read the graph from
35  std::ifstream is(argv[1]);
36
37  typedef SmartGraph Graph;
38
39  typedef Graph::Edge Edge;
40  typedef Graph::Node Node;
41  typedef Graph::EdgeIt EdgeIt;
42  typedef Graph::NodeIt NodeIt;
43  typedef Graph::EdgeMap<int> LengthMap;
44
45  Graph g;
46  Node s, t;
47  LengthMap length(g);
48
49  readDimacs(is, g, length, s, t);
50
51  cout << "edges with lengths (of form id, source--length->target): " << endl;
52  for(EdgeIt e(g); e!=INVALID; ++e)
53    cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--"
54         << length[e] << "->" << g.id(g.target(e)) << endl;
55
56  cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;
57
58  typedef Dijkstra<Graph, LengthMap> Dijkstra;
59  Dijkstra dijkstra(g, length);
60  dijkstra.run(s);
61
62  // This map returns true exactly for those edges which are
63  // tight w.r.t the length funcion and the potential
64  // given by the dijkstra algorithm.
65  typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap>
66    TightEdgeFilter;
67  TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);
68
69//  ConstMap<Node, bool> const_true_map(true);
70  // This graph contains exaclty the tight edges.
71// typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
72  typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;
73  SubGW gw(g, tight_edge_filter);
74
75  ConstMap<Edge, int> const_1_map(1);
76  Graph::EdgeMap<int> flow(g, 0);
77  // Max flow between s and t in the graph of tight edges.
78  Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> >
79    preflow(gw, s, t, const_1_map, flow);
80  preflow.run();
81
82  cout << "maximum number of edge-disjoint shortest paths: "
83       << preflow.flowValue() << endl;
84  cout << "edges of the maximum number of edge-disjoint shortest s-t paths: "
85       << endl;
86  for(EdgeIt e(g); e!=INVALID; ++e)
87    if (flow[e])
88      cout << " " << g.id(e) << ", "
89           << g.id(g.source(e)) << "--"
90           << length[e] << "->" << g.id(g.target(e)) << endl;
91}
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