1 | // -*- C++ -*- |
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2 | //The same as preflow.h, using ResGraphWrapper |
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3 | #ifndef LEMON_PREFLOW_RES_H |
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4 | #define LEMON_PREFLOW_RES_H |
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5 | |
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6 | #define H0 20 |
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7 | #define H1 1 |
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8 | |
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9 | #include <vector> |
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10 | #include <queue> |
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11 | #include <graph_wrapper.h> |
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12 | |
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13 | #include<iostream> |
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14 | |
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15 | namespace lemon { |
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16 | |
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17 | template <typename Graph, typename T, |
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18 | typename CapMap=typename Graph::template EdgeMap<T>, |
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19 | typename FlowMap=typename Graph::template EdgeMap<T> > |
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20 | class PreflowRes { |
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21 | |
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22 | typedef typename Graph::Node Node; |
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23 | typedef typename Graph::Edge Edge; |
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24 | typedef typename Graph::NodeIt NodeIt; |
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25 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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26 | typedef typename Graph::InEdgeIt InEdgeIt; |
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27 | |
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28 | const Graph& G; |
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29 | Node s; |
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30 | Node t; |
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31 | const CapMap& capacity; |
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32 | FlowMap& flow; |
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33 | T value; |
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34 | bool constzero; |
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35 | |
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36 | typedef ResGraphWrapper<const Graph, T, CapMap, FlowMap> ResGW; |
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37 | typedef typename ResGW::OutEdgeIt ResOutEdgeIt; |
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38 | typedef typename ResGW::InEdgeIt ResInEdgeIt; |
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39 | typedef typename ResGW::Edge ResEdge; |
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40 | |
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41 | public: |
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42 | PreflowRes(Graph& _G, Node _s, Node _t, CapMap& _capacity, |
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43 | FlowMap& _flow, bool _constzero ) : |
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44 | G(_G), s(_s), t(_t), capacity(_capacity), flow(_flow), constzero(_constzero) {} |
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45 | |
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46 | |
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47 | void run() { |
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48 | |
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49 | ResGW res_graph(G, capacity, flow); |
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50 | |
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51 | value=0; //for the subsequent runs |
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52 | |
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53 | bool phase=0; //phase 0 is the 1st phase, phase 1 is the 2nd |
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54 | int n=G.nodeNum(); |
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55 | int heur0=(int)(H0*n); //time while running 'bound decrease' |
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56 | int heur1=(int)(H1*n); //time while running 'highest label' |
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57 | int heur=heur1; //starting time interval (#of relabels) |
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58 | bool what_heur=1; |
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59 | /* |
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60 | what_heur is 0 in case 'bound decrease' |
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61 | and 1 in case 'highest label' |
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62 | */ |
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63 | bool end=false; |
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64 | /* |
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65 | Needed for 'bound decrease', 'true' |
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66 | means no active nodes are above bound b. |
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67 | */ |
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68 | int relabel=0; |
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69 | int k=n-2; //bound on the highest level under n containing a node |
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70 | int b=k; //bound on the highest level under n of an active node |
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71 | |
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72 | typename Graph::template NodeMap<int> level(G,n); |
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73 | typename Graph::template NodeMap<T> excess(G); |
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74 | |
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75 | std::vector<Node> active(n-1,INVALID); |
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76 | typename Graph::template NodeMap<Node> next(G,INVALID); |
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77 | //Stack of the active nodes in level i < n. |
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78 | //We use it in both phases. |
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79 | |
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80 | typename Graph::template NodeMap<Node> left(G,INVALID); |
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81 | typename Graph::template NodeMap<Node> right(G,INVALID); |
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82 | std::vector<Node> level_list(n,INVALID); |
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83 | /* |
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84 | List of the nodes in level i<n. |
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85 | */ |
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86 | |
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87 | |
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88 | /* |
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89 | Reverse_bfs from t in the residual graph, |
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90 | to find the starting level. |
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91 | */ |
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92 | level.set(t,0); |
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93 | std::queue<Node> bfs_queue; |
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94 | bfs_queue.push(t); |
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95 | |
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96 | while (!bfs_queue.empty()) { |
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97 | |
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98 | Node v=bfs_queue.front(); |
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99 | bfs_queue.pop(); |
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100 | int l=level[v]+1; |
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101 | |
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102 | ResInEdgeIt e; |
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103 | for(res_graph.first(e,v); res_graph.valid(e); |
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104 | res_graph.next(e)) { |
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105 | Node w=res_graph.source(e); |
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106 | if ( level[w] == n && w != s ) { |
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107 | bfs_queue.push(w); |
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108 | Node first=level_list[l]; |
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109 | if ( G.valid(first) ) left.set(first,w); |
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110 | right.set(w,first); |
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111 | level_list[l]=w; |
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112 | level.set(w, l); |
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113 | } |
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114 | } |
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115 | } |
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116 | |
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117 | |
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118 | if ( !constzero ) { |
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119 | /* |
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120 | Counting the excess |
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121 | */ |
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122 | NodeIt v; |
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123 | for(G.first(v); G.valid(v); G.next(v)) { |
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124 | T exc=0; |
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125 | |
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126 | InEdgeIt e; |
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127 | for(G.first(e,v); G.valid(e); G.next(e)) exc+=flow[e]; |
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128 | OutEdgeIt f; |
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129 | for(G.first(f,v); G.valid(f); G.next(f)) exc-=flow[f]; |
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130 | |
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131 | excess.set(v,exc); |
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132 | |
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133 | //putting the active nodes into the stack |
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134 | int lev=level[v]; |
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135 | if ( exc > 0 && lev < n ) { |
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136 | next.set(v,active[lev]); |
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137 | active[lev]=v; |
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138 | } |
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139 | } |
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140 | } |
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141 | |
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142 | |
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143 | |
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144 | //the starting flow |
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145 | ResOutEdgeIt e; |
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146 | for(res_graph.first(e,s); res_graph.valid(e); |
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147 | res_graph.next(e)) { |
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148 | Node w=res_graph.target(e); |
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149 | if ( level[w] < n ) { |
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150 | if ( excess[w] == 0 && w!=t ) { |
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151 | next.set(w,active[level[w]]); |
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152 | active[level[w]]=w; |
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153 | } |
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154 | T rem=res_graph.resCap(e); |
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155 | excess.set(w, excess[w]+rem); |
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156 | res_graph.augment(e, rem ); |
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157 | } |
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158 | } |
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159 | |
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160 | |
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161 | /* |
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162 | End of preprocessing |
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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 | Push/relabel on the highest level active nodes. |
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169 | */ |
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170 | while ( true ) { |
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171 | |
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172 | if ( b == 0 ) { |
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173 | if ( phase ) break; |
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174 | |
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175 | if ( !what_heur && !end && k > 0 ) { |
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176 | b=k; |
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177 | end=true; |
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178 | } else { |
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179 | phase=1; |
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180 | level.set(s,0); |
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181 | std::queue<Node> bfs_queue; |
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182 | bfs_queue.push(s); |
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183 | |
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184 | while (!bfs_queue.empty()) { |
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185 | |
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186 | Node v=bfs_queue.front(); |
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187 | bfs_queue.pop(); |
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188 | int l=level[v]+1; |
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189 | |
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190 | ResInEdgeIt e; |
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191 | for(res_graph.first(e,v); |
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192 | res_graph.valid(e); res_graph.next(e)) { |
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193 | Node u=res_graph.source(e); |
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194 | if ( level[u] >= n ) { |
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195 | bfs_queue.push(u); |
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196 | level.set(u, l); |
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197 | if ( excess[u] > 0 ) { |
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198 | next.set(u,active[l]); |
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199 | active[l]=u; |
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200 | } |
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201 | } |
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202 | } |
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203 | |
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204 | } |
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205 | b=n-2; |
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206 | } |
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207 | |
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208 | } |
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209 | |
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210 | |
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211 | if ( !G.valid(active[b]) ) --b; |
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212 | else { |
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213 | end=false; |
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214 | |
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215 | Node w=active[b]; |
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216 | active[b]=next[w]; |
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217 | int lev=level[w]; |
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218 | T exc=excess[w]; |
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219 | int newlevel=n; //bound on the next level of w |
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220 | |
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221 | ResOutEdgeIt e; |
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222 | for(res_graph.first(e,w); res_graph.valid(e); res_graph.next(e)) { |
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223 | |
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224 | Node v=res_graph.target(e); |
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225 | if( lev > level[v] ) { |
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226 | /*Push is allowed now*/ |
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227 | |
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228 | if ( excess[v]==0 && v!=t && v!=s ) { |
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229 | int lev_v=level[v]; |
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230 | next.set(v,active[lev_v]); |
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231 | active[lev_v]=v; |
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232 | } |
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233 | |
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234 | T remcap=res_graph.resCap(e); |
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235 | |
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236 | if ( remcap >= exc ) { |
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237 | /*A nonsaturating push.*/ |
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238 | res_graph.augment(e, exc); |
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239 | excess.set(v, excess[v]+exc); |
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240 | exc=0; |
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241 | break; |
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242 | |
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243 | } else { |
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244 | /*A saturating push.*/ |
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245 | |
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246 | res_graph.augment(e, remcap); |
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247 | excess.set(v, excess[v]+remcap); |
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248 | exc-=remcap; |
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249 | } |
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250 | } else if ( newlevel > level[v] ){ |
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251 | newlevel = level[v]; |
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252 | } |
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253 | |
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254 | } |
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255 | |
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256 | excess.set(w, exc); |
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257 | |
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258 | /* |
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259 | Relabel |
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260 | */ |
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261 | |
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262 | |
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263 | if ( exc > 0 ) { |
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264 | //now 'lev' is the old level of w |
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265 | |
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266 | if ( phase ) { |
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267 | level.set(w,++newlevel); |
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268 | next.set(w,active[newlevel]); |
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269 | active[newlevel]=w; |
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270 | b=newlevel; |
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271 | } else { |
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272 | //unlacing starts |
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273 | Node right_n=right[w]; |
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274 | Node left_n=left[w]; |
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275 | |
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276 | if ( G.valid(right_n) ) { |
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277 | if ( G.valid(left_n) ) { |
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278 | right.set(left_n, right_n); |
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279 | left.set(right_n, left_n); |
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280 | } else { |
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281 | level_list[lev]=right_n; |
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282 | left.set(right_n, INVALID); |
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283 | } |
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284 | } else { |
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285 | if ( G.valid(left_n) ) { |
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286 | right.set(left_n, INVALID); |
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287 | } else { |
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288 | level_list[lev]=INVALID; |
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289 | } |
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290 | } |
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291 | //unlacing ends |
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292 | |
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293 | if ( !G.valid(level_list[lev]) ) { |
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294 | |
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295 | //gapping starts |
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296 | for (int i=lev; i!=k ; ) { |
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297 | Node v=level_list[++i]; |
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298 | while ( G.valid(v) ) { |
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299 | level.set(v,n); |
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300 | v=right[v]; |
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301 | } |
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302 | level_list[i]=INVALID; |
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303 | if ( !what_heur ) active[i]=INVALID; |
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304 | } |
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305 | |
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306 | level.set(w,n); |
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307 | b=lev-1; |
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308 | k=b; |
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309 | //gapping ends |
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310 | |
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311 | } else { |
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312 | |
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313 | if ( newlevel == n ) level.set(w,n); |
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314 | else { |
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315 | level.set(w,++newlevel); |
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316 | next.set(w,active[newlevel]); |
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317 | active[newlevel]=w; |
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318 | if ( what_heur ) b=newlevel; |
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319 | if ( k < newlevel ) ++k; //now k=newlevel |
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320 | Node first=level_list[newlevel]; |
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321 | if ( G.valid(first) ) left.set(first,w); |
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322 | right.set(w,first); |
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323 | left.set(w,INVALID); |
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324 | level_list[newlevel]=w; |
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325 | } |
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326 | } |
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327 | |
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328 | |
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329 | ++relabel; |
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330 | if ( relabel >= heur ) { |
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331 | relabel=0; |
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332 | if ( what_heur ) { |
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333 | what_heur=0; |
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334 | heur=heur0; |
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335 | end=false; |
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336 | } else { |
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337 | what_heur=1; |
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338 | heur=heur1; |
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339 | b=k; |
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340 | } |
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341 | } |
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342 | } //phase 0 |
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343 | |
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344 | |
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345 | } // if ( exc > 0 ) |
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346 | |
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347 | |
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348 | } // if stack[b] is nonempty |
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349 | |
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350 | } // while(true) |
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351 | |
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352 | |
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353 | value = excess[t]; |
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354 | /*Max flow value.*/ |
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355 | |
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356 | } //void run() |
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357 | |
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358 | |
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359 | |
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360 | |
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361 | |
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362 | /* |
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363 | Returns the maximum value of a flow. |
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364 | */ |
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365 | |
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366 | T flowValue() { |
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367 | return value; |
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368 | } |
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369 | |
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370 | |
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371 | FlowMap Flow() { |
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372 | return flow; |
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373 | } |
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374 | |
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375 | |
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376 | |
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377 | void Flow(FlowMap& _flow ) { |
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378 | NodeIt v; |
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379 | for(G.first(v) ; G.valid(v); G.next(v)) |
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380 | _flow.set(v,flow[v]); |
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381 | } |
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382 | |
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383 | |
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384 | |
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385 | /* |
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386 | Returns the minimum min cut, by a bfs from s in the residual graph. |
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387 | */ |
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388 | |
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389 | template<typename _CutMap> |
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390 | void minMinCut(_CutMap& M) { |
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391 | |
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392 | std::queue<Node> queue; |
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393 | |
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394 | M.set(s,true); |
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395 | queue.push(s); |
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396 | |
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397 | while (!queue.empty()) { |
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398 | Node w=queue.front(); |
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399 | queue.pop(); |
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400 | |
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401 | OutEdgeIt e; |
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402 | for(G.first(e,w) ; G.valid(e); G.next(e)) { |
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403 | Node v=G.target(e); |
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404 | if (!M[v] && flow[e] < capacity[e] ) { |
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405 | queue.push(v); |
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406 | M.set(v, true); |
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407 | } |
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408 | } |
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409 | |
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410 | InEdgeIt f; |
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411 | for(G.first(f,w) ; G.valid(f); G.next(f)) { |
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412 | Node v=G.source(f); |
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413 | if (!M[v] && flow[f] > 0 ) { |
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414 | queue.push(v); |
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415 | M.set(v, true); |
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416 | } |
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417 | } |
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418 | } |
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419 | } |
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420 | |
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421 | |
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422 | |
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423 | /* |
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424 | Returns the maximum min cut, by a reverse bfs |
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425 | from t in the residual graph. |
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426 | */ |
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427 | |
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428 | template<typename _CutMap> |
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429 | void maxMinCut(_CutMap& M) { |
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430 | |
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431 | std::queue<Node> queue; |
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432 | |
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433 | M.set(t,true); |
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434 | queue.push(t); |
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435 | |
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436 | while (!queue.empty()) { |
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437 | Node w=queue.front(); |
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438 | queue.pop(); |
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439 | |
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440 | |
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441 | InEdgeIt e; |
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442 | for(G.first(e,w) ; G.valid(e); G.next(e)) { |
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443 | Node v=G.source(e); |
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444 | if (!M[v] && flow[e] < capacity[e] ) { |
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445 | queue.push(v); |
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446 | M.set(v, true); |
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447 | } |
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448 | } |
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449 | |
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450 | OutEdgeIt f; |
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451 | for(G.first(f,w) ; G.valid(f); G.next(f)) { |
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452 | Node v=G.target(f); |
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453 | if (!M[v] && flow[f] > 0 ) { |
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454 | queue.push(v); |
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455 | M.set(v, true); |
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456 | } |
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457 | } |
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458 | } |
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459 | |
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460 | NodeIt v; |
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461 | for(G.first(v) ; G.valid(v); G.next(v)) { |
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462 | M.set(v, !M[v]); |
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463 | } |
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464 | |
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465 | } |
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466 | |
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467 | |
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468 | |
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469 | template<typename CutMap> |
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470 | void minCut(CutMap& M) { |
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471 | minMinCut(M); |
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472 | } |
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473 | |
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474 | |
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475 | |
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476 | void resetTarget (Node _t) {t=_t;} |
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477 | void resetSource (Node _s) {s=_s;} |
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478 | |
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479 | void resetCap (CapMap _cap) {capacity=_cap;} |
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480 | |
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481 | void resetFlow (FlowMap _flow, bool _constzero) { |
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482 | flow=_flow; |
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483 | constzero=_constzero; |
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484 | } |
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485 | |
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486 | |
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487 | }; |
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488 | |
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489 | } //namespace lemon |
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490 | |
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491 | #endif //LEMON_PREFLOW_RES_H |
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492 | |
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493 | |
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494 | |
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495 | |
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