1 | #ifndef LEMON_NEAREST_NEIGHBOUR_TSP_H |
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2 | #define LEMON_NEAREST_NEIGHBOUR_TSP_H |
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3 | |
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4 | #include <deque> |
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5 | #include <lemon/full_graph.h> |
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6 | #include <lemon/path.h> |
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7 | #include <lemon/maps.h> |
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8 | |
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9 | namespace lemon { |
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10 | |
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11 | namespace nn_helper { |
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12 | template <class L> |
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13 | L dequeConvert(const std::deque<FullGraph::Node> &_path) { |
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14 | return L(_path.begin(), _path.end()); |
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15 | } |
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16 | |
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17 | template <> |
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18 | std::deque<FullGraph::Node> dequeConvert(const std::deque<FullGraph::Node> &_path) { |
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19 | return _path; |
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20 | } |
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21 | } |
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22 | |
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23 | template <typename CM> |
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24 | class NearestNeighborTsp { |
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25 | private: |
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26 | GRAPH_TYPEDEFS(FullGraph); |
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27 | |
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28 | public: |
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29 | typedef CM CostMap; |
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30 | typedef typename CM::Value Cost; |
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31 | |
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32 | NearestNeighborTsp(const FullGraph &gr, const CostMap &cost) : _gr(gr), _cost(cost) {} |
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33 | |
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34 | Cost run() { |
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35 | _path.clear(); |
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36 | |
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37 | Edge min_edge1 = INVALID, |
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38 | min_edge2 = INVALID; |
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39 | |
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40 | min_edge1 = mapMin(_gr, _cost); |
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41 | |
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42 | FullGraph::NodeMap<bool> used(_gr, false); |
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43 | |
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44 | Node n1 = _gr.u(min_edge1), |
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45 | n2 = _gr.v(min_edge1); |
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46 | |
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47 | _path.push_back(n1); |
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48 | _path.push_back(n2); |
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49 | |
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50 | used[n1] = true; |
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51 | used[n2] = true; |
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52 | |
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53 | min_edge1 = INVALID; |
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54 | |
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55 | while (int(_path.size()) != _gr.nodeNum()) { |
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56 | if (min_edge1 == INVALID) { |
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57 | for (IncEdgeIt e(_gr, n1); e!=INVALID; ++e) { |
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58 | if (!used[_gr.runningNode(e)]) { |
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59 | if (min_edge1==INVALID || _cost[min_edge1] > _cost[e]) |
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60 | min_edge1 = e; |
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61 | } |
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62 | } |
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63 | } |
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64 | |
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65 | if (min_edge2 == INVALID) { |
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66 | for (IncEdgeIt e(_gr, n2); e!=INVALID; ++e) { |
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67 | if (!used[_gr.runningNode(e)]) { |
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68 | if (min_edge2==INVALID || _cost[min_edge2] > _cost[e]) |
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69 | min_edge2 = e; |
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70 | } |
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71 | } |
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72 | } |
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73 | |
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74 | if ( _cost[min_edge1] < _cost[min_edge2] ) { |
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75 | n1 = (_gr.u(min_edge1) == n1) ? _gr.v(min_edge1) : _gr.u(min_edge1); |
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76 | _path.push_front(n1); |
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77 | |
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78 | used[n1] = true; |
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79 | min_edge1 = INVALID; |
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80 | |
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81 | if (_gr.u(min_edge2)==n1 || _gr.v(min_edge2)==n1) |
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82 | min_edge2 = INVALID; |
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83 | } else { |
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84 | n2 = (_gr.u(min_edge2) == n2) ? _gr.v(min_edge2) : _gr.u(min_edge2); |
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85 | _path.push_back(n2); |
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86 | |
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87 | used[n2] = true; |
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88 | min_edge2 = INVALID; |
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89 | |
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90 | if (_gr.u(min_edge1)==n2 || _gr.v(min_edge1)==n2) |
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91 | min_edge1 = INVALID; |
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92 | } |
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93 | } |
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94 | |
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95 | _sum = _cost[ _gr.edge(_path.back(), _path.front()) ]; |
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96 | for (unsigned int i=0; i<_path.size()-1; ++i) |
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97 | _sum += _cost[ _gr.edge(_path[i], _path[i+1]) ]; |
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98 | |
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99 | return _sum; |
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100 | } |
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101 | |
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102 | |
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103 | template <typename L> |
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104 | void tourNodes(L &container) { |
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105 | container(nn_helper::dequeConvert<L>(_path)); |
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106 | } |
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107 | |
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108 | template <template <typename> class L> |
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109 | L<Node> tourNodes() { |
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110 | return nn_helper::dequeConvert<L<Node> >(_path); |
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111 | } |
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112 | |
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113 | const std::deque<Node>& tourNodes() { |
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114 | return _path; |
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115 | } |
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116 | |
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117 | Path<FullGraph> tour() { |
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118 | Path<FullGraph> p; |
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119 | if (_path.size()<2) |
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120 | return p; |
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121 | |
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122 | for (unsigned int i=0; i<_path.size()-1; ++i) { |
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123 | p.addBack(_gr.arc(_path[i], _path[i+1])); |
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124 | } |
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125 | p.addBack(_gr.arc(_path.back(), _path.front())); |
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126 | |
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127 | return p; |
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128 | } |
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129 | |
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130 | Cost tourCost() { |
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131 | return _sum; |
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132 | } |
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133 | |
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134 | |
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135 | private: |
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136 | const FullGraph &_gr; |
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137 | const CostMap &_cost; |
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138 | Cost _sum; |
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139 | std::deque<Node> _path; |
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140 | }; |
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141 | |
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142 | |
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143 | }; // namespace lemon |
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144 | |
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145 | #endif |
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