1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2006 |
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6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 | * |
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9 | * Permission to use, modify and distribute this software is granted |
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10 | * provided that this copyright notice appears in all copies. For |
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11 | * precise terms see the accompanying LICENSE file. |
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12 | * |
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13 | * This software is provided "AS IS" with no warranty of any kind, |
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14 | * express or implied, and with no claim as to its suitability for any |
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15 | * purpose. |
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16 | * |
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17 | */ |
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18 | |
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19 | #include <iostream> |
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20 | |
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21 | #include <lemon/smart_graph.h> |
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22 | #include <lemon/graph_reader.h> |
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23 | #include <lemon/ugraph_adaptor.h> |
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24 | #include <lemon/graph_to_eps.h> |
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25 | #include <lemon/dfs.h> |
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26 | #include <lemon/topology.h> |
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27 | |
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28 | |
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29 | /// \ingroup demos |
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30 | /// \file |
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31 | /// \brief Strongly connected orientation |
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32 | /// |
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33 | /// This example demonstrates the usage of the DirUGraphAdaptor, |
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34 | /// the DfsVisitor and some topology functions. The program reads |
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35 | /// an input undirected graph and with a DfsVisit it orients each edge |
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36 | /// to minimize the strongly connected components in the graph. At least |
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37 | /// it checks the result of the orientation with to topology functions. |
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38 | /// |
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39 | /// \include strongly_connected_orientation.cc |
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40 | |
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41 | using namespace lemon; |
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42 | using namespace std; |
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43 | |
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44 | typedef SmartUGraph UGraph; |
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45 | UGRAPH_TYPEDEFS(UGraph) |
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46 | |
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47 | Color color(bool c) { |
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48 | return c ? BLACK : RED; |
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49 | } |
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50 | |
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51 | template <typename DirMap> |
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52 | class OrientVisitor : public DfsVisitor<UGraph> { |
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53 | public: |
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54 | |
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55 | OrientVisitor(const UGraph& ugraph, DirMap& dirMap) |
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56 | : _ugraph(ugraph), _dirMap(dirMap), _processed(ugraph, false) {} |
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57 | |
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58 | void discover(const Edge& edge) { |
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59 | _processed.set(edge, true); |
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60 | _dirMap.set(edge, _ugraph.direction(edge)); |
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61 | } |
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62 | |
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63 | void examine(const Edge& edge) { |
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64 | if (_processed[edge]) return; |
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65 | _processed.set(edge, true); |
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66 | _dirMap.set(edge, _ugraph.direction(edge)); |
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67 | } |
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68 | |
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69 | private: |
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70 | const UGraph& _ugraph; |
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71 | DirMap& _dirMap; |
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72 | UGraph::UEdgeMap<bool> _processed; |
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73 | }; |
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74 | |
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75 | |
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76 | int main() { |
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77 | cout << "Orientation of the strongly_connected_orientation.lgf " |
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78 | << "to be strongly connected" << endl; |
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79 | |
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80 | UGraph ugraph; |
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81 | UGraph::NodeMap<dim2::Point<double> > coords(ugraph); |
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82 | UGraphReader<UGraph>("strongly_connected_orientation.lgf", ugraph). |
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83 | readNodeMap("coords", coords).run(); |
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84 | |
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85 | UGraph::UEdgeMap<bool> dmap(ugraph); |
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86 | |
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87 | typedef OrientVisitor<UGraph::UEdgeMap<bool> > Visitor; |
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88 | Visitor visitor(ugraph, dmap); |
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89 | |
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90 | DfsVisit<UGraph, Visitor> dfs(ugraph, visitor); |
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91 | |
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92 | dfs.run(); |
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93 | |
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94 | typedef DirUGraphAdaptor<UGraph> DGraph; |
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95 | DGraph dgraph(ugraph, dmap); |
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96 | |
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97 | cout << "The result written into the " |
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98 | << "strongly_connected_orientation.eps file" << endl; |
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99 | |
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100 | graphToEps(dgraph, "strongly_connected_orientation.eps"). |
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101 | drawArrows().coords(coords).scaleToA4().enableParallel(). |
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102 | autoNodeScale().autoEdgeWidthScale().run(); |
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103 | |
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104 | int num_scc = countStronglyConnectedComponents(dgraph); |
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105 | int num_becc = countBiEdgeConnectedComponents(ugraph); |
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106 | |
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107 | if (num_scc != num_becc) { |
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108 | std::cerr << "Wrong Orientation" << std::endl; |
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109 | } |
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110 | |
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111 | return 0; |
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112 | } |
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