1 | #ifndef EDMONDS_KARP_HH |
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2 | #define EDMONDS_KARP_HH |
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3 | |
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4 | #include <algorithm> |
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5 | |
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6 | #include <bfs_iterator.hh> |
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7 | |
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8 | namespace marci { |
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9 | |
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10 | template<typename Graph, typename T, typename FlowMap, typename CapacityMap> |
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11 | class ResGraph { |
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12 | typedef typename Graph::NodeIt NodeIt; |
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13 | typedef typename Graph::EachNodeIt EachNodeIt; |
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14 | typedef typename Graph::SymEdgeIt OldSymEdgeIt; |
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15 | const Graph& G; |
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16 | FlowMap& flow; |
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17 | const CapacityMap& capacity; |
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18 | public: |
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19 | ResGraph(const Graph& _G, FlowMap& _flow, |
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20 | const CapacityMap& _capacity) : |
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21 | G(_G), flow(_flow), capacity(_capacity) { } |
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22 | |
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23 | class EdgeIt; |
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24 | class OutEdgeIt; |
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25 | friend class EdgeIt; |
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26 | friend class OutEdgeIt; |
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27 | |
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28 | class EdgeIt { |
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29 | friend class ResGraph<Graph, T, FlowMap, CapacityMap>; |
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30 | protected: |
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31 | const ResGraph<Graph, T, FlowMap, CapacityMap>* resG; |
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32 | OldSymEdgeIt sym; |
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33 | public: |
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34 | EdgeIt() { } |
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35 | //EdgeIt(const EdgeIt& e) : resG(e.resG), sym(e.sym) { } |
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36 | T free() const { |
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37 | if (resG->G.aNode(sym)==resG->G.tail(sym)) { |
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38 | return (resG->capacity.get(sym)-resG->flow.get(sym)); |
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39 | } else { |
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40 | return (resG->flow.get(sym)); |
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41 | } |
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42 | } |
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43 | bool valid() const { return sym.valid(); } |
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44 | void augment(T a) const { |
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45 | if (resG->G.aNode(sym)==resG->G.tail(sym)) { |
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46 | resG->flow.set(sym, resG->flow.get(sym)+a); |
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47 | } else { |
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48 | resG->flow.set(sym, resG->flow.get(sym)-a); |
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49 | } |
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50 | } |
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51 | }; |
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52 | |
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53 | class OutEdgeIt : public EdgeIt { |
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54 | friend class ResGraph<Graph, T, FlowMap, CapacityMap>; |
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55 | public: |
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56 | OutEdgeIt() { } |
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57 | //OutEdgeIt(const OutEdgeIt& e) { resG=e.resG; sym=e.sym; } |
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58 | private: |
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59 | OutEdgeIt(const ResGraph<Graph, T, FlowMap, CapacityMap>& _resG, NodeIt v) { |
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60 | resG=&_resG; |
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61 | sym=resG->G.template first<OldSymEdgeIt>(v); |
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62 | while( sym.valid() && !(free()>0) ) { ++sym; } |
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63 | } |
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64 | public: |
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65 | OutEdgeIt& operator++() { |
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66 | ++sym; |
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67 | while( sym.valid() && !(free()>0) ) { ++sym; } |
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68 | return *this; |
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69 | } |
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70 | }; |
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71 | |
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72 | void getFirst(OutEdgeIt& e, NodeIt v) const { |
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73 | e=OutEdgeIt(*this, v); |
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74 | } |
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75 | void getFirst(EachNodeIt& v) const { G.getFirst(v); } |
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76 | |
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77 | template< typename It > |
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78 | It first() const { |
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79 | It e; |
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80 | getFirst(e); |
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81 | return e; |
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82 | } |
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83 | |
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84 | template< typename It > |
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85 | It first(NodeIt v) const { |
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86 | It e; |
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87 | getFirst(e, v); |
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88 | return e; |
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89 | } |
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90 | |
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91 | NodeIt tail(EdgeIt e) const { return G.aNode(e.sym); } |
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92 | NodeIt head(EdgeIt e) const { return G.bNode(e.sym); } |
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93 | |
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94 | NodeIt aNode(OutEdgeIt e) const { return G.aNode(e.sym); } |
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95 | NodeIt bNode(OutEdgeIt e) const { return G.bNode(e.sym); } |
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96 | |
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97 | int id(NodeIt v) const { return G.id(v); } |
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98 | |
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99 | template <typename S> |
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100 | class NodeMap { |
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101 | typename Graph::NodeMap<S> node_map; |
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102 | public: |
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103 | NodeMap(const ResGraph<Graph, T, FlowMap, CapacityMap>& _G) : node_map(_G.G) { } |
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104 | NodeMap(const ResGraph<Graph, T, FlowMap, CapacityMap>& _G, S a) : node_map(_G.G, a) { } |
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105 | void set(NodeIt nit, S a) { node_map.set(nit, a); } |
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106 | S get(NodeIt nit) const { return node_map.get(nit); } |
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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 | template <typename Graph, typename T, typename FlowMap, typename CapacityMap> |
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112 | class MaxFlow { |
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113 | typedef typename Graph::NodeIt NodeIt; |
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114 | typedef typename Graph::EdgeIt EdgeIt; |
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115 | typedef typename Graph::EachEdgeIt EachEdgeIt; |
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116 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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117 | typedef typename Graph::InEdgeIt InEdgeIt; |
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118 | const Graph& G; |
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119 | NodeIt s; |
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120 | NodeIt t; |
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121 | FlowMap& flow; |
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122 | const CapacityMap& capacity; |
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123 | typedef ResGraph<Graph, T, FlowMap, CapacityMap > AugGraph; |
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124 | typedef typename AugGraph::OutEdgeIt AugOutEdgeIt; |
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125 | typedef typename AugGraph::EdgeIt AugEdgeIt; |
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126 | public: |
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127 | MaxFlow(const Graph& _G, NodeIt _s, NodeIt _t, FlowMap& _flow, const CapacityMap& _capacity) : G(_G), s(_s), t(_t), flow(_flow), capacity(_capacity) { } |
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128 | bool augment() { |
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129 | AugGraph res_graph(G, flow, capacity); |
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130 | bool _augment=false; |
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131 | |
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132 | typedef typename AugGraph::NodeMap<bool> ReachedMap; |
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133 | BfsIterator2< AugGraph, AugOutEdgeIt, ReachedMap > res_bfs(res_graph); |
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134 | res_bfs.pushAndSetReached(s); |
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135 | |
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136 | typename AugGraph::NodeMap<AugEdgeIt> pred(res_graph); |
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137 | //filled with invalid iterators |
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138 | |
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139 | typename AugGraph::NodeMap<int> free(res_graph); |
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140 | |
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141 | //searching for augmenting path |
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142 | while ( !res_bfs.finished() ) { |
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143 | AugOutEdgeIt e=AugOutEdgeIt(res_bfs); |
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144 | if (e.valid() && res_bfs.isBNodeNewlyReached()) { |
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145 | NodeIt v=res_graph.tail(e); |
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146 | NodeIt w=res_graph.head(e); |
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147 | pred.set(w, e); |
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148 | if (pred.get(v).valid()) { |
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149 | free.set(w, std::min(free.get(v), e.free())); |
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150 | } else { |
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151 | free.set(w, e.free()); |
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152 | } |
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153 | if (res_graph.head(e)==t) { _augment=true; break; } |
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154 | } |
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155 | |
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156 | ++res_bfs; |
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157 | } //end of searching augmenting path |
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158 | |
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159 | if (_augment) { |
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160 | NodeIt n=t; |
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161 | T augment_value=free.get(t); |
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162 | while (pred.get(n).valid()) { |
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163 | AugEdgeIt e=pred.get(n); |
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164 | e.augment(augment_value); |
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165 | n=res_graph.tail(e); |
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166 | } |
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167 | } |
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168 | |
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169 | return _augment; |
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170 | } |
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171 | void run() { |
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172 | while (augment()) { } |
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173 | } |
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174 | T flowValue() { |
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175 | T a=0; |
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176 | for(OutEdgeIt i=G.template first<OutEdgeIt>(s); i.valid(); ++i) { |
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177 | a+=flow.get(i); |
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178 | } |
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179 | return a; |
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180 | } |
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181 | }; |
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182 | |
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183 | } // namespace marci |
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184 | |
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185 | #endif //EDMONDS_KARP_HH |
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