[1578] | 1 | /* -*- C++ -*- |
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| 2 | * |
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[1956] | 3 | * This file is a part of LEMON, a generic C++ optimization library |
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| 4 | * |
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[2391] | 5 | * Copyright (C) 2003-2007 |
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[1956] | 6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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[1578] | 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 Minimum weight spanning tree by Kruskal algorithm (demo). |
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| 22 | /// |
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[1583] | 23 | /// This demo program shows how to find a minimum weight spanning tree |
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| 24 | /// in a graph by using the Kruskal algorithm. |
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[1641] | 25 | /// |
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| 26 | /// \include kruskal_demo.cc |
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[1578] | 27 | |
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[1182] | 28 | #include <iostream> |
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| 29 | #include <vector> |
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| 30 | |
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| 31 | #include <lemon/maps.h> |
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| 32 | #include <lemon/kruskal.h> |
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| 33 | #include <lemon/list_graph.h> |
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| 34 | |
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| 35 | |
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| 36 | using namespace std; |
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| 37 | using namespace lemon; |
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| 38 | |
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| 39 | |
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| 40 | int main() { |
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| 41 | |
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| 42 | typedef ListGraph::Node Node; |
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| 43 | typedef ListGraph::Edge Edge; |
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| 44 | typedef ListGraph::NodeIt NodeIt; |
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| 45 | typedef ListGraph::EdgeIt EdgeIt; |
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| 46 | |
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[1578] | 47 | ListGraph g; |
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| 48 | //Make an example graph g. |
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| 49 | Node s=g.addNode(); |
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| 50 | Node v1=g.addNode(); |
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| 51 | Node v2=g.addNode(); |
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| 52 | Node v3=g.addNode(); |
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| 53 | Node v4=g.addNode(); |
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| 54 | Node t=g.addNode(); |
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| 55 | |
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| 56 | Edge e1 = g.addEdge(s, v1); |
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| 57 | Edge e2 = g.addEdge(s, v2); |
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| 58 | Edge e3 = g.addEdge(v1, v2); |
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| 59 | Edge e4 = g.addEdge(v2, v1); |
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| 60 | Edge e5 = g.addEdge(v1, v3); |
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| 61 | Edge e6 = g.addEdge(v3, v2); |
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| 62 | Edge e7 = g.addEdge(v2, v4); |
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| 63 | Edge e8 = g.addEdge(v4, v3); |
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| 64 | Edge e9 = g.addEdge(v3, t); |
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| 65 | Edge e10 = g.addEdge(v4, t); |
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[1182] | 66 | |
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[1584] | 67 | //Make the input for the kruskal. |
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[1182] | 68 | typedef ListGraph::EdgeMap<int> ECostMap; |
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[1584] | 69 | ECostMap edge_cost_map(g); |
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| 70 | |
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| 71 | // Fill the edge_cost_map. |
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| 72 | edge_cost_map.set(e1, -10); |
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| 73 | edge_cost_map.set(e2, -9); |
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| 74 | edge_cost_map.set(e3, -8); |
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| 75 | edge_cost_map.set(e4, -7); |
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| 76 | edge_cost_map.set(e5, -6); |
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| 77 | edge_cost_map.set(e6, -5); |
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| 78 | edge_cost_map.set(e7, -4); |
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| 79 | edge_cost_map.set(e8, -3); |
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| 80 | edge_cost_map.set(e9, -2); |
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| 81 | edge_cost_map.set(e10, -1); |
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| 82 | |
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| 83 | // Make the map or the vector, which will contain the edges of the minimum |
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| 84 | // spanning tree. |
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| 85 | |
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[1182] | 86 | typedef ListGraph::EdgeMap<bool> EBoolMap; |
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[1578] | 87 | EBoolMap tree_map(g); |
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[1182] | 88 | |
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| 89 | vector<Edge> tree_edge_vec; |
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| 90 | |
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| 91 | |
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[1584] | 92 | //Kruskal Algorithm. |
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[1182] | 93 | |
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[1584] | 94 | //Input: a graph (g); a costmap of the graph (edge_cost_map); a |
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| 95 | //boolmap (tree_map) or a vector (tree_edge_vec) to store the edges |
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| 96 | //of the output tree; |
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[1182] | 97 | |
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[1584] | 98 | //Output: it gives back the value of the minimum spanning tree, and |
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| 99 | //set true for the edges of the tree in the edgemap tree_map or |
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| 100 | //store the edges of the tree in the vector tree_edge_vec; |
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| 101 | |
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| 102 | |
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| 103 | // Kruskal with boolmap; |
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| 104 | std::cout << "The weight of the minimum spanning tree is " << |
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| 105 | kruskal(g, edge_cost_map, tree_map)<<std::endl; |
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| 106 | |
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| 107 | int k=0; |
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| 108 | std::cout << "The edges of the tree:" ; |
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[2281] | 109 | for(EdgeIt i(g); i!=INVALID; ++i) |
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[1584] | 110 | if (tree_map[i]) { |
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| 111 | std::cout << g.id(i) <<";"; |
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| 112 | ++k; |
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| 113 | } |
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[2281] | 114 | |
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[1584] | 115 | std::cout << std::endl; |
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| 116 | std::cout << "The size of the tree is: "<< k << std::endl; |
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| 117 | |
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| 118 | |
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| 119 | // Kruskal with vector; |
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[1578] | 120 | std::cout << "The weight of the minimum spanning tree again is " << |
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[1584] | 121 | kruskal(g, edge_cost_map, std::back_inserter(tree_edge_vec)) <<std::endl; |
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[1182] | 122 | |
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[1578] | 123 | |
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[1584] | 124 | |
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| 125 | std::cout << "The edges of the tree again: " ; |
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| 126 | for(int i=tree_edge_vec.size()-1; i>=0; i--) |
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| 127 | std::cout << g.id(tree_edge_vec[i]) << ";" ; |
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| 128 | std::cout << std::endl; |
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[1641] | 129 | std::cout << "The size of the tree again is: "<< tree_edge_vec.size() |
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| 130 | << std::endl; |
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[1584] | 131 | |
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| 132 | |
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[1182] | 133 | return 0; |
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| 134 | } |
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