1 | /* -*- C++ -*- |
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2 | * demo/kruskal_demo.cc - Part of LEMON, a generic C++ optimization library |
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3 | * |
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4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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6 | * |
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7 | * Permission to use, modify and distribute this software is granted |
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8 | * provided that this copyright notice appears in all copies. For |
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9 | * precise terms see the accompanying LICENSE file. |
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10 | * |
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11 | * This software is provided "AS IS" with no warranty of any kind, |
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12 | * express or implied, and with no claim as to its suitability for any |
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13 | * purpose. |
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14 | * |
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15 | */ |
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16 | |
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17 | ///\ingroup demos |
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18 | ///\file |
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19 | ///\brief Minimum weight spanning tree by Kruskal algorithm (demo). |
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20 | /// |
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21 | /// This demo program shows how to find a minimum weight spanning tree |
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22 | /// in a graph by using the Kruskal algorithm. |
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23 | |
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24 | #include <iostream> |
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25 | #include <vector> |
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26 | |
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27 | #include <lemon/maps.h> |
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28 | #include <lemon/kruskal.h> |
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29 | #include <lemon/list_graph.h> |
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30 | |
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31 | |
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32 | using namespace std; |
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33 | using namespace lemon; |
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34 | |
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35 | |
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36 | int main() { |
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37 | |
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38 | typedef ListGraph::Node Node; |
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39 | typedef ListGraph::Edge Edge; |
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40 | typedef ListGraph::NodeIt NodeIt; |
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41 | typedef ListGraph::EdgeIt EdgeIt; |
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42 | |
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43 | ListGraph g; |
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44 | //Make an example graph g. |
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45 | Node s=g.addNode(); |
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46 | Node v1=g.addNode(); |
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47 | Node v2=g.addNode(); |
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48 | Node v3=g.addNode(); |
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49 | Node v4=g.addNode(); |
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50 | Node t=g.addNode(); |
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51 | |
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52 | Edge e1 = g.addEdge(s, v1); |
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53 | Edge e2 = g.addEdge(s, v2); |
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54 | Edge e3 = g.addEdge(v1, v2); |
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55 | Edge e4 = g.addEdge(v2, v1); |
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56 | Edge e5 = g.addEdge(v1, v3); |
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57 | Edge e6 = g.addEdge(v3, v2); |
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58 | Edge e7 = g.addEdge(v2, v4); |
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59 | Edge e8 = g.addEdge(v4, v3); |
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60 | Edge e9 = g.addEdge(v3, t); |
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61 | Edge e10 = g.addEdge(v4, t); |
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62 | |
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63 | //Make the input and output for the kruskal. |
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64 | typedef ListGraph::EdgeMap<int> ECostMap; |
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65 | typedef ListGraph::EdgeMap<bool> EBoolMap; |
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66 | |
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67 | ECostMap edge_cost_map(g, 2); |
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68 | EBoolMap tree_map(g); |
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69 | |
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70 | // Kruskal. |
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71 | std::cout << "The weight of the minimum spanning tree by using Kruskal algorithm is " |
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72 | << kruskal(g, ConstMap<ListGraph::Edge,int>(2), tree_map)<<std::endl; |
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73 | |
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74 | //Make another input (non-uniform costs) for the kruskal. |
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75 | ECostMap edge_cost_map_2(g); |
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76 | edge_cost_map_2.set(e1, -10); |
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77 | edge_cost_map_2.set(e2, -9); |
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78 | edge_cost_map_2.set(e3, -8); |
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79 | edge_cost_map_2.set(e4, -7); |
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80 | edge_cost_map_2.set(e5, -6); |
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81 | edge_cost_map_2.set(e6, -5); |
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82 | edge_cost_map_2.set(e7, -4); |
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83 | edge_cost_map_2.set(e8, -3); |
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84 | edge_cost_map_2.set(e9, -2); |
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85 | edge_cost_map_2.set(e10, -1); |
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86 | |
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87 | vector<Edge> tree_edge_vec; |
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88 | |
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89 | //Test with non uniform costs and inserter. |
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90 | std::cout << "The weight of the minimum spanning tree with non-uniform costs is " << |
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91 | kruskal(g, edge_cost_map_2, std::back_inserter(tree_edge_vec)) <<std::endl; |
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92 | |
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93 | //The vector for the edges of the output tree. |
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94 | tree_edge_vec.clear(); |
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95 | |
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96 | //Test with makeKruskalMapInput and makeKruskalSequenceOutput. |
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97 | |
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98 | std::cout << "The weight of the minimum spanning tree again is " << |
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99 | kruskal(g,makeKruskalMapInput(g,edge_cost_map_2),makeKruskalSequenceOutput(std::back_inserter(tree_edge_vec)))<< std::endl; |
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100 | |
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101 | |
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102 | return 0; |
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103 | } |
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