COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/sub_graph_adaptor_demo.cc

Last change on this file was 2553:bfced05fa852, checked in by Alpar Juttner, 12 years ago

Happy New Year to LEMON (+ better update-copyright-header script)

File size: 3.6 KB
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1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2008
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19///\ingroup demos
20///\file
21///\brief Computing maximum number of edge-disjoint shortest paths
22///
23/// This program computes a maximum number of edge-disjoint shortest paths
24/// between nodes \c s and \c t.
25///
26/// \include sub_graph_adaptor_demo.cc
27
28// Use a DIMACS max flow file as input.
29// sub_graph_adaptor_demo < dimacs_max_flow_file
30// Modified to eat lemon graph format!
31
32
33#include <iostream>
34#include <fstream>
35
36#include <lemon/smart_graph.h>
37#include <lemon/dijkstra.h>
38#include <lemon/maps.h>
39#include <lemon/graph_adaptor.h>
40#include <lemon/dimacs.h>
41#include <lemon/preflow.h>
42#include "tight_edge_filter_map.h"
43
44#include <lemon/graph_reader.h>
45
46
47using namespace lemon;
48
49using std::cout;
50using std::endl;
51
52int main(int argc, char *argv[])
53{
54  if(argc<2)
55  {
56      std::cerr << "USAGE: sub_graph_adaptor_demo input_file.lgf" << std::endl;
57      std::cerr << "The file 'input_file.lgf' has to contain a max flow "
58                << "instance in \n LEMON format "
59                << "(e.g. sub_gad_input.lgf is such a file)."
60                << std::endl;
61      return 0;
62  }
63
64
65  //input stream to read the graph from
66  std::ifstream is(argv[1]);
67
68  typedef SmartGraph Graph;
69
70  typedef Graph::Edge Edge;
71  typedef Graph::Node Node;
72  typedef Graph::EdgeIt EdgeIt;
73  typedef Graph::NodeIt NodeIt;
74  typedef Graph::EdgeMap<int> LengthMap;
75
76  Graph g;
77  Node s, t;
78  LengthMap length(g);
79
80  //readDimacs(is, g, length, s, t);
81
82
83  GraphReader<SmartGraph> reader(is,g);
84  reader.readNode("source",s).readNode("target",t)
85    .readEdgeMap("length",length).run();
86
87  cout << "edges with lengths (of form id, source--length->target): " << endl;
88  for(EdgeIt e(g); e!=INVALID; ++e)
89    cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--"
90         << length[e] << "->" << g.id(g.target(e)) << endl;
91
92  cout << "s: " << g.id(s) << " t: " << g.id(t) << endl;
93
94  typedef Dijkstra<Graph, LengthMap> Dijkstra;
95  Dijkstra dijkstra(g, length);
96  dijkstra.run(s);
97
98  // This map returns true exactly for those edges which are
99  // tight w.r.t the length funcion and the potential
100  // given by the dijkstra algorithm.
101  typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap>
102    TightEdgeFilter;
103  TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length);
104
105//  ConstMap<Node, bool> const_true_map(true);
106  // This graph contains exaclty the tight edges.
107// typedef SubGraphAdaptor<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW;
108  typedef EdgeSubGraphAdaptor<Graph, TightEdgeFilter> SubGW;
109  SubGW gw(g, tight_edge_filter);
110
111  ConstMap<Edge, int> const_1_map(1);
112  // Max flow between s and t in the graph of tight edges.
113  Preflow<SubGW, ConstMap<Edge, int> > preflow(gw, const_1_map, s, t);
114  preflow.run();
115
116  cout << "maximum number of edge-disjoint shortest paths: "
117       << preflow.flowValue() << endl;
118  cout << "edges of the maximum number of edge-disjoint shortest s-t paths: "
119       << endl;
120  for(EdgeIt e(g); e!=INVALID; ++e)
121    if (preflow.flow(e) != 0)
122      cout << " " << g.id(e) << ", "
123           << g.id(g.source(e)) << "--"
124           << length[e] << "->" << g.id(g.target(e)) << endl;
125}
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