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 | /// \ingroup demos |
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20 | /// \file |
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21 | /// \brief Node and edge disjoint paths in directed graph. |
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22 | /// |
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23 | /// This demo program calculates how many edge disjoint and node disjoint |
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24 | /// paths are in a directed graph between a source and a target node. |
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25 | /// The edge disjoint paths can be computed with a flow algorithm, |
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26 | /// in this example we use the Preflow algorithm class. To get the node |
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27 | /// disjoint paths we should first adapt the graph with the SplitGraphAdaptor |
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28 | /// and just then calculate the flow. |
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29 | /// |
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30 | /// \include disjoint_paths.cc |
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31 | |
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32 | #include <iostream> |
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33 | |
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34 | #include <lemon/smart_graph.h> |
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35 | #include <lemon/graph_adaptor.h> |
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36 | #include <lemon/graph_reader.h> |
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37 | #include <lemon/preflow.h> |
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38 | #include <lemon/graph_to_eps.h> |
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39 | |
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40 | using namespace lemon; |
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41 | using namespace std; |
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42 | |
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43 | Color color(bool b) { |
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44 | return b ? Color(1.0, 0.0, 0.0) : Color(0.0, 0.0, 0.0); |
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45 | } |
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46 | |
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47 | int main() { |
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48 | cout << "This program calculates the number " << |
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49 | "of disjoint paths in a graph" << endl; |
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50 | cout << "The graph is read from the disjoint_paths.lgf file" << endl; |
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51 | typedef SmartGraph Graph; |
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52 | |
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53 | Graph graph; |
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54 | |
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55 | Graph::NodeMap<xy<double> > coords(graph); |
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56 | Graph::Node source, target; |
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57 | GraphReader<Graph>("disjoint_paths.lgf", graph). |
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58 | readNodeMap("coords", coords). |
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59 | readNode("source", source).readNode("target", target).run(); |
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60 | |
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61 | typedef ConstMap<Graph::Edge, int> Capacity; |
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62 | Capacity capacity(1); |
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63 | |
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64 | Graph::EdgeMap<int> flow(graph); |
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65 | |
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66 | Preflow<Graph, int, Capacity> preflow(graph, source, target, capacity, flow); |
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67 | |
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68 | preflow.run(); |
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69 | |
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70 | cout << "Number of edge disjoint paths: " << preflow.flowValue() << endl; |
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71 | |
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72 | graphToEps(graph, "edge_disjoint.eps"). |
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73 | title("edge disjoint path").copyright("(C) 2006 LEMON Project").drawArrows(). |
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74 | edgeColors(composeMap(functorMap(color), flow)). |
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75 | coords(coords).autoNodeScale().run(); |
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76 | |
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77 | |
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78 | cout << "The paths are written into edge_disjoint.eps" << endl; |
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79 | |
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80 | typedef SplitGraphAdaptor<SmartGraph> SGraph; |
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81 | |
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82 | SGraph sgraph(graph); |
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83 | |
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84 | typedef ConstMap<SGraph::Edge, int> SCapacity; |
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85 | SCapacity scapacity(1); |
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86 | |
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87 | SGraph::EdgeMap<int> sflow(sgraph); |
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88 | |
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89 | Preflow<SGraph, int, SCapacity> spreflow(sgraph, SGraph::outNode(source), |
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90 | SGraph::inNode(target), |
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91 | scapacity, sflow); |
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92 | |
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93 | spreflow.run(); |
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94 | |
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95 | cout << "Number of node disjoint paths: " << spreflow.flowValue() << endl; |
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96 | |
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97 | |
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98 | graphToEps(sgraph, "node_disjoint.eps"). |
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99 | title("node disjoint path").copyright("(C) 2006 LEMON Project").drawArrows(). |
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100 | edgeColors(composeMap(functorMap(color), sflow)). |
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101 | coords(SGraph::combinedNodeMap(coords, shiftMap(coords, xy<double>(5, 0)))). |
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102 | autoNodeScale().run(); |
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103 | |
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104 | cout << "The paths are written into node_disjoint.eps" << endl; |
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105 | |
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106 | return 0; |
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107 | } |
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