1 | // -*- C++ -*- |
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2 | |
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3 | //kell hogy tree_edge invalid elekbol alljon, Szep |
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4 | //lenne ha az elejen a konstrualas ilyet adna, de |
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5 | //ugy fest nem igy lesz, ekkor invalidalni kell |
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6 | |
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7 | /* |
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8 | *template <Graph, T, Heap=FibHeap> |
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9 | * |
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10 | *Constructor: |
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11 | * |
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12 | *Prim(Graph G, Graph::EdgeMap<T> weight, NodeIt root=[G.first()]) |
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13 | * |
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14 | * |
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15 | *Methods: |
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16 | * |
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17 | *void run() |
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18 | * |
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19 | * The followings functions should be used after run() was already run. |
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20 | * |
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21 | *T weight() : returns the minimum weight of a spanning tree of the |
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22 | * component of the root. |
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23 | * |
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24 | *EdgeIt tree(NodeIt v) : returns the first edge in the path from v |
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25 | * to the root. Returns an invalid iterator if v=s or v is |
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26 | * not reachable from the root. |
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27 | * |
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28 | *bool conn() : true iff G is connected |
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29 | * |
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30 | *bool reach(NodeIt v) : true iff v is in the same component as the root |
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31 | * |
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32 | *NodeIt root() : returns the root |
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33 | * |
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34 | */ |
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35 | |
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36 | #ifndef PRIM_H |
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37 | #define PRIM_H |
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38 | |
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39 | #include <fib_heap.h> |
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40 | |
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41 | #include <iostream> |
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42 | |
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43 | namespace hugo { |
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44 | |
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45 | template <typename Graph, typename T, |
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46 | typename Heap=FibHeap<typename Graph::NodeIt, T, |
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47 | typename Graph::NodeMap<int> > > |
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48 | class Prim{ |
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49 | typedef typename Graph::NodeIt NodeIt; |
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50 | typedef typename Graph::EachNodeIt EachNodeIt; |
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51 | typedef typename Graph::EdgeIt EdgeIt; |
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52 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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53 | typedef typename Graph::InEdgeIt InEdgeIt; |
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54 | |
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55 | Graph& G; |
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56 | NodeIt r; |
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57 | typename Graph::NodeMap<EdgeIt> tree_edge; |
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58 | typename Graph::NodeMap<T> min_weight; |
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59 | typename Graph::EdgeMap<T>& edge_weight; |
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60 | typename Graph::NodeMap<bool> reached; |
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61 | |
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62 | public : |
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63 | |
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64 | Prim(Graph& _G, typename Graph::EdgeMap<T>& _edge_weight, |
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65 | NodeIt const _r) : |
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66 | G(_G), r(_r), tree_edge(G), min_weight(G), |
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67 | edge_weight(_edge_weight), reached(G, false) { } |
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68 | |
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69 | Prim(Graph& _G, typename Graph::EdgeMap<T>& _edge_weight) : |
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70 | G(_G), tree_edge(G), min_weight(G), edge_weight(_edge_weight), reached(G, false) |
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71 | { |
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72 | EachNodeIt _r; //FIXME |
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73 | G.getFirst(_r); |
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74 | r=_r; |
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75 | } |
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76 | |
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77 | |
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78 | void run() { |
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79 | |
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80 | typename Graph::NodeMap<bool> scanned(G, false); |
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81 | typename Graph::NodeMap<int> heap_map(G,-1); |
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82 | |
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83 | Heap heap(heap_map); |
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84 | |
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85 | heap.push(r,0); |
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86 | reached.set(r, true); |
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87 | |
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88 | while ( !heap.empty() ) { |
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89 | |
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90 | NodeIt v=heap.top(); |
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91 | min_weight.set(v, heap.get(v)); |
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92 | heap.pop(); |
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93 | scanned.set(v,true); |
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94 | |
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95 | OutEdgeIt e; |
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96 | for( G.getFirst(e,v); G.valid(e); G.next(e)) { |
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97 | NodeIt w=G.head(e); |
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98 | |
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99 | if ( !scanned.get(w) ) { |
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100 | if ( !reached.get(w) ) { |
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101 | reached.set(w,true); |
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102 | heap.push(w, edge_weight.get(e)); |
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103 | tree_edge.set(w,e); |
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104 | } else if ( edge_weight.get(e) < heap.get(w) ) { |
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105 | tree_edge.set(w,e); |
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106 | heap.decrease(w, edge_weight.get(e)); |
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107 | } |
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108 | } |
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109 | } |
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110 | |
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111 | InEdgeIt f; |
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112 | for( G.getFirst(f,v); G.valid(f); G.next(f)) { |
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113 | NodeIt w=G.tail(f); |
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114 | |
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115 | if ( !scanned.get(w) ) { |
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116 | if ( !reached.get(w) ) { |
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117 | reached.set(w,true); |
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118 | heap.push(w, edge_weight.get(f)); |
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119 | tree_edge.set(w,f); |
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120 | } else if ( edge_weight.get(f) < heap.get(w) ) { |
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121 | tree_edge.set(w,f); |
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122 | heap.decrease(w, edge_weight.get(f)); |
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123 | } |
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124 | } |
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125 | } |
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126 | } |
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127 | } |
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128 | |
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129 | |
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130 | T weight() { |
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131 | T w=0; |
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132 | EachNodeIt u; |
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133 | for ( G.getFirst(u) ; G.valid(u) ; G.next(u) ) w+=min_weight.get(u); |
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134 | return w; |
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135 | } |
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136 | |
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137 | |
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138 | EdgeIt tree(NodeIt v) { |
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139 | return tree_edge.get(v); |
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140 | } |
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141 | |
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142 | |
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143 | bool conn() { |
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144 | bool c=true; |
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145 | EachNodeIt u; |
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146 | for ( G.getFirst(u) ; G.valid(u) ; G.next(u) ) |
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147 | if ( !reached.get(u) ) { |
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148 | c=false; |
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149 | break; |
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150 | } |
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151 | return c; |
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152 | } |
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153 | |
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154 | |
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155 | bool reach(NodeIt v) { |
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156 | return reached.get(v); |
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157 | } |
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158 | |
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159 | |
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160 | NodeIt root() { |
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161 | return r; |
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162 | } |
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163 | |
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164 | }; |
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165 | |
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166 | } |
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167 | |
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168 | #endif |
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169 | |
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170 | |
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