COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/sub_graph_adaptor_demo.cc @ 1875:98698b69a902

Last change on this file since 1875:98698b69a902 was 1875:98698b69a902, checked in by Alpar Juttner, 14 years ago

Happy new year to LEMON

File size: 3.7 KB
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1/* -*- C++ -*-
2 * demo/sub_graph_adaptor_demo.cc - Part of LEMON, a generic C++ optimization
3 * library
4 *
5 * Copyright (C) 2006 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
6 * (Egervary Research Group on Combinatorial Optimization, EGRES).
7 *
8 * Permission to use, modify and distribute this software is granted
9 * provided that this copyright notice appears in all copies. For
10 * precise terms see the accompanying LICENSE file.
11 *
12 * This software is provided "AS IS" with no warranty of any kind,
13 * express or implied, and with no claim as to its suitability for any
14 * purpose.
15 *
16 */
17
18///\ingroup demos
19///\file
20///\brief Computing maximum number of edge-disjoint shortest paths
21///
22/// This program computes a maximum number of edge-disjoint shortest paths
23/// between nodes \c s and \c t.
24///
25/// \include sub_graph_adaptor_demo.cc
26
27// Use a DIMACS max flow file as input.
28// sub_graph_adaptor_demo < dimacs_max_flow_file
29// Modified to eat lemon graph format!
30
31
32#include <iostream>
33#include <fstream>
34
35#include <lemon/smart_graph.h>
36#include <lemon/dijkstra.h>
37#include <lemon/maps.h>
38#include <lemon/graph_adaptor.h>
39#include <lemon/dimacs.h>
40#include <lemon/preflow.h>
41#include <tight_edge_filter_map.h>
42
43#include <lemon/graph_reader.h>
44
45
46using namespace lemon;
47
48using std::cout;
49using std::endl;
50
51int main(int argc, char *argv[])
52{
53  if(argc<2)
54  {
55      std::cerr << "USAGE: sub_graph_adaptor_demo input_file.lgf" << std::endl;
56      std::cerr << "The file 'input_file.lgf' has to contain a max flow "
57                << "instance in \n LEMON format "
58                << "(e.g. sub_gad_input.lgf is such a file)."
59                << std::endl;
60      return 0;
61  }
62
63
64  //input stream to read the graph from
65  std::ifstream is(argv[1]);
66
67  typedef SmartGraph Graph;
68
69  typedef Graph::Edge Edge;
70  typedef Graph::Node Node;
71  typedef Graph::EdgeIt EdgeIt;
72  typedef Graph::NodeIt NodeIt;
73  typedef Graph::EdgeMap<int> LengthMap;
74
75  Graph g;
76  Node s, t;
77  LengthMap length(g);
78
79  //readDimacs(is, g, length, s, t);
80
81
82  GraphReader<SmartGraph> reader(is,g);
83  reader.readNode("source",s).readNode("target",t)
84    .readEdgeMap("length",length).run();
85
86  cout << "edges with lengths (of form id, source--length->target): " << endl;
87  for(EdgeIt e(g); e!=INVALID; ++e)
88    cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--"
89         << length[e] << "->" << g.id(g.target(e)) << endl;
90
91  cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;
92
93  typedef Dijkstra<Graph, LengthMap> Dijkstra;
94  Dijkstra dijkstra(g, length);
95  dijkstra.run(s);
96
97  // This map returns true exactly for those edges which are
98  // tight w.r.t the length funcion and the potential
99  // given by the dijkstra algorithm.
100  typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap>
101    TightEdgeFilter;
102  TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);
103
104//  ConstMap<Node, bool> const_true_map(true);
105  // This graph contains exaclty the tight edges.
106// typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
107  typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;
108  SubGW gw(g, tight_edge_filter);
109
110  ConstMap<Edge, int> const_1_map(1);
111  Graph::EdgeMap<int> flow(g, 0);
112  // Max flow between s and t in the graph of tight edges.
113  Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> >
114    preflow(gw, s, t, const_1_map, flow);
115  preflow.run();
116
117  cout << "maximum number of edge-disjoint shortest paths: "
118       << preflow.flowValue() << endl;
119  cout << "edges of the maximum number of edge-disjoint shortest s-t paths: "
120       << endl;
121  for(EdgeIt e(g); e!=INVALID; ++e)
122    if (flow[e])
123      cout << " " << g.id(e) << ", "
124           << g.id(g.source(e)) << "--"
125           << length[e] << "->" << g.id(g.target(e)) << endl;
126}
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