1 | // -*- C++ -*- |
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2 | |
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3 | //run gyorsan tudna adni a minmincutot a 2 fazis elejen , ne vegyuk be konstruktorba egy cutmapet? |
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4 | //constzero jo igy? |
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5 | |
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6 | //majd marci megmondja betegyem-e bfs-t meg resgraphot |
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7 | |
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8 | //constzero helyett az kell hogy flow-e vagy csak preflow, ha flow akor csak |
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9 | //excess[t]-t kell szmaolni |
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10 | |
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11 | /* |
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12 | Heuristics: |
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13 | 2 phase |
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14 | gap |
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15 | list 'level_list' on the nodes on level i implemented by hand |
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16 | stack 'active' on the active nodes on level i implemented by hand |
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17 | runs heuristic 'highest label' for H1*n relabels |
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18 | runs heuristic 'bound decrease' for H0*n relabels, starts with 'highest label' |
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19 | |
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20 | Parameters H0 and H1 are initialized to 20 and 10. |
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21 | |
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22 | Constructors: |
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23 | |
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24 | Preflow(Graph, Node, Node, CapMap, FlowMap, bool) : bool must be false if |
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25 | FlowMap is not constant zero, and should be true if it is |
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26 | |
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27 | Members: |
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28 | |
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29 | void run() |
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30 | |
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31 | T flowValue() : returns the value of a maximum flow |
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32 | |
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33 | void minMinCut(CutMap& M) : sets M to the characteristic vector of the |
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34 | minimum min cut. M should be a map of bools initialized to false. |
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35 | |
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36 | void maxMinCut(CutMap& M) : sets M to the characteristic vector of the |
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37 | maximum min cut. M should be a map of bools initialized to false. |
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38 | |
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39 | void minCut(CutMap& M) : sets M to the characteristic vector of |
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40 | a min cut. M should be a map of bools initialized to false. |
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41 | |
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42 | FIXME reset |
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43 | |
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44 | */ |
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45 | |
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46 | #ifndef LEMON_PREFLOW_H |
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47 | #define LEMON_PREFLOW_H |
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48 | |
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49 | #define H0 20 |
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50 | #define H1 1 |
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51 | |
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52 | #include <vector> |
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53 | #include <queue> |
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54 | #include <stack> |
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55 | |
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56 | namespace lemon { |
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57 | |
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58 | template <typename Graph, typename T, |
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59 | typename CapMap=typename Graph::template EdgeMap<T>, |
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60 | typename FlowMap=typename Graph::template EdgeMap<T> > |
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61 | class Preflow { |
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62 | |
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63 | typedef typename Graph::Node Node; |
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64 | typedef typename Graph::Edge Edge; |
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65 | typedef typename Graph::NodeIt NodeIt; |
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66 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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67 | typedef typename Graph::InEdgeIt InEdgeIt; |
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68 | |
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69 | const Graph& G; |
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70 | Node s; |
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71 | Node t; |
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72 | const CapMap& capacity; |
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73 | FlowMap& flow; |
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74 | T value; |
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75 | bool constzero; |
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76 | bool isflow; |
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77 | |
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78 | public: |
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79 | Preflow(Graph& _G, Node _s, Node _t, CapMap& _capacity, |
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80 | FlowMap& _flow, bool _constzero, bool _isflow ) : |
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81 | G(_G), s(_s), t(_t), capacity(_capacity), flow(_flow), constzero(_constzero), isflow(_isflow) {} |
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82 | |
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83 | |
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84 | void run() { |
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85 | |
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86 | value=0; //for the subsequent runs |
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87 | |
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88 | bool phase=0; //phase 0 is the 1st phase, phase 1 is the 2nd |
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89 | int n=G.nodeNum(); |
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90 | int heur0=(int)(H0*n); //time while running 'bound decrease' |
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91 | int heur1=(int)(H1*n); //time while running 'highest label' |
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92 | int heur=heur1; //starting time interval (#of relabels) |
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93 | bool what_heur=1; |
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94 | /* |
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95 | what_heur is 0 in case 'bound decrease' |
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96 | and 1 in case 'highest label' |
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97 | */ |
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98 | bool end=false; |
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99 | /* |
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100 | Needed for 'bound decrease', 'true' |
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101 | means no active nodes are above bound b. |
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102 | */ |
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103 | int relabel=0; |
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104 | int k=n-2; //bound on the highest level under n containing a node |
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105 | int b=k; //bound on the highest level under n of an active node |
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106 | |
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107 | typename Graph::template NodeMap<int> level(G,n); |
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108 | typename Graph::template NodeMap<T> excess(G); |
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109 | |
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110 | std::vector<std::stack<Node> > active(n); |
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111 | /* std::vector<Node> active(n-1,INVALID); |
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112 | typename Graph::template NodeMap<Node> next(G,INVALID); |
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113 | //Stack of the active nodes in level i < n. |
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114 | //We use it in both phases.*/ |
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115 | |
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116 | typename Graph::template NodeMap<Node> left(G,INVALID); |
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117 | typename Graph::template NodeMap<Node> right(G,INVALID); |
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118 | std::vector<Node> level_list(n,INVALID); |
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119 | /* |
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120 | List of the nodes in level i<n. |
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121 | */ |
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122 | |
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123 | |
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124 | if ( constzero ) { |
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125 | |
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126 | /*Reverse_bfs from t, to find the starting level.*/ |
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127 | level.set(t,0); |
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128 | std::queue<Node> bfs_queue; |
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129 | bfs_queue.push(t); |
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130 | |
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131 | while (!bfs_queue.empty()) { |
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132 | |
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133 | Node v=bfs_queue.front(); |
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134 | bfs_queue.pop(); |
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135 | int l=level[v]+1; |
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136 | |
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137 | InEdgeIt e; |
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138 | for(G.first(e,v); G.valid(e); G.next(e)) { |
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139 | Node w=G.tail(e); |
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140 | if ( level[w] == n && w != s ) { |
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141 | bfs_queue.push(w); |
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142 | Node first=level_list[l]; |
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143 | if ( G.valid(first) ) left.set(first,w); |
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144 | right.set(w,first); |
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145 | level_list[l]=w; |
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146 | level.set(w, l); |
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147 | } |
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148 | } |
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149 | } |
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150 | |
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151 | //the starting flow |
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152 | OutEdgeIt e; |
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153 | for(G.first(e,s); G.valid(e); G.next(e)) |
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154 | { |
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155 | T c=capacity[e]; |
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156 | if ( c == 0 ) continue; |
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157 | Node w=G.head(e); |
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158 | if ( level[w] < n ) { |
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159 | if ( excess[w] == 0 && w!=t ) active[level[w]].push(w); |
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160 | flow.set(e, c); |
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161 | excess.set(w, excess[w]+c); |
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162 | } |
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163 | } |
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164 | } |
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165 | else |
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166 | { |
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167 | |
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168 | /* |
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169 | Reverse_bfs from t in the residual graph, |
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170 | to find the starting level. |
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171 | */ |
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172 | level.set(t,0); |
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173 | std::queue<Node> bfs_queue; |
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174 | bfs_queue.push(t); |
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175 | |
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176 | while (!bfs_queue.empty()) { |
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177 | |
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178 | Node v=bfs_queue.front(); |
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179 | bfs_queue.pop(); |
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180 | int l=level[v]+1; |
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181 | |
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182 | InEdgeIt e; |
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183 | for(G.first(e,v); G.valid(e); G.next(e)) { |
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184 | if ( capacity[e] == flow[e] ) continue; |
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185 | Node w=G.tail(e); |
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186 | if ( level[w] == n && w != s ) { |
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187 | bfs_queue.push(w); |
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188 | Node first=level_list[l]; |
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189 | if ( G.valid(first) ) left.set(first,w); |
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190 | right.set(w,first); |
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191 | level_list[l]=w; |
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192 | level.set(w, l); |
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193 | } |
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194 | } |
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195 | |
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196 | OutEdgeIt f; |
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197 | for(G.first(f,v); G.valid(f); G.next(f)) { |
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198 | if ( 0 == flow[f] ) continue; |
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199 | Node w=G.head(f); |
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200 | if ( level[w] == n && w != s ) { |
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201 | bfs_queue.push(w); |
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202 | Node first=level_list[l]; |
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203 | if ( G.valid(first) ) left.set(first,w); |
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204 | right.set(w,first); |
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205 | level_list[l]=w; |
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206 | level.set(w, l); |
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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 | |
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212 | /* |
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213 | Counting the excess |
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214 | */ |
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215 | |
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216 | if ( !isflow ) { |
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217 | NodeIt v; |
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218 | for(G.first(v); G.valid(v); G.next(v)) { |
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219 | T exc=0; |
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220 | |
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221 | InEdgeIt e; |
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222 | for(G.first(e,v); G.valid(e); G.next(e)) exc+=flow[e]; |
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223 | OutEdgeIt f; |
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224 | for(G.first(f,v); G.valid(f); G.next(f)) exc-=flow[f]; |
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225 | |
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226 | excess.set(v,exc); |
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227 | |
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228 | //putting the active nodes into the stack |
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229 | int lev=level[v]; |
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230 | if ( exc > 0 && lev < n && v != t ) active[lev].push(v); |
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231 | } |
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232 | } else { |
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233 | T exc=0; |
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234 | |
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235 | InEdgeIt e; |
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236 | for(G.first(e,t); G.valid(e); G.next(e)) exc+=flow[e]; |
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237 | OutEdgeIt f; |
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238 | for(G.first(f,t); G.valid(f); G.next(f)) exc-=flow[f]; |
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239 | |
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240 | excess.set(t,exc); |
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241 | } |
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242 | |
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243 | |
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244 | //the starting flow |
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245 | OutEdgeIt e; |
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246 | for(G.first(e,s); G.valid(e); G.next(e)) |
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247 | { |
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248 | T rem=capacity[e]-flow[e]; |
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249 | if ( rem == 0 ) continue; |
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250 | Node w=G.head(e); |
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251 | if ( level[w] < n ) { |
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252 | if ( excess[w] == 0 && w!=t ) active[level[w]].push(w); |
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253 | flow.set(e, capacity[e]); |
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254 | excess.set(w, excess[w]+rem); |
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255 | } |
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256 | } |
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257 | |
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258 | InEdgeIt f; |
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259 | for(G.first(f,s); G.valid(f); G.next(f)) |
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260 | { |
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261 | if ( flow[f] == 0 ) continue; |
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262 | Node w=G.tail(f); |
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263 | if ( level[w] < n ) { |
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264 | if ( excess[w] == 0 && w!=t ) active[level[w]].push(w); |
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265 | excess.set(w, excess[w]+flow[f]); |
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266 | flow.set(f, 0); |
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267 | } |
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268 | } |
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269 | } |
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270 | |
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271 | |
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272 | |
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273 | |
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274 | /* |
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275 | End of preprocessing |
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276 | */ |
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277 | |
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278 | |
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279 | |
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280 | /* |
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281 | Push/relabel on the highest level active nodes. |
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282 | */ |
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283 | while ( true ) { |
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284 | |
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285 | if ( b == 0 ) { |
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286 | if ( phase ) break; |
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287 | |
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288 | if ( !what_heur && !end && k > 0 ) { |
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289 | b=k; |
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290 | end=true; |
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291 | } else { |
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292 | phase=1; |
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293 | level.set(s,0); |
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294 | std::queue<Node> bfs_queue; |
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295 | bfs_queue.push(s); |
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296 | |
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297 | while (!bfs_queue.empty()) { |
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298 | |
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299 | Node v=bfs_queue.front(); |
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300 | bfs_queue.pop(); |
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301 | int l=level[v]+1; |
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302 | |
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303 | InEdgeIt e; |
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304 | for(G.first(e,v); G.valid(e); G.next(e)) { |
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305 | if ( capacity[e] == flow[e] ) continue; |
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306 | Node u=G.tail(e); |
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307 | if ( level[u] >= n ) { |
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308 | bfs_queue.push(u); |
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309 | level.set(u, l); |
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310 | if ( excess[u] > 0 ) active[l].push(u); |
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311 | } |
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312 | } |
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313 | |
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314 | OutEdgeIt f; |
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315 | for(G.first(f,v); G.valid(f); G.next(f)) { |
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316 | if ( 0 == flow[f] ) continue; |
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317 | Node u=G.head(f); |
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318 | if ( level[u] >= n ) { |
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319 | bfs_queue.push(u); |
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320 | level.set(u, l); |
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321 | if ( excess[u] > 0 ) active[l].push(u); |
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322 | } |
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323 | } |
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324 | } |
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325 | b=n-2; |
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326 | } |
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327 | |
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328 | } |
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329 | |
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330 | |
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331 | /// |
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332 | if ( active[b].empty() ) --b; |
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333 | else { |
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334 | end=false; |
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335 | |
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336 | Node w=active[b].top(); |
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337 | active[b].pop(); |
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338 | int lev=level[w]; |
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339 | T exc=excess[w]; |
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340 | int newlevel=n; //bound on the next level of w |
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341 | |
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342 | OutEdgeIt e; |
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343 | for(G.first(e,w); G.valid(e); G.next(e)) { |
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344 | |
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345 | if ( flow[e] == capacity[e] ) continue; |
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346 | Node v=G.head(e); |
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347 | //e=wv |
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348 | |
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349 | if( lev > level[v] ) { |
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350 | /*Push is allowed now*/ |
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351 | |
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352 | if ( excess[v]==0 && v!=t && v!=s ) { |
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353 | int lev_v=level[v]; |
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354 | active[lev_v].push(v); |
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355 | } |
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356 | |
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357 | T cap=capacity[e]; |
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358 | T flo=flow[e]; |
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359 | T remcap=cap-flo; |
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360 | |
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361 | if ( remcap >= exc ) { |
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362 | /*A nonsaturating push.*/ |
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363 | |
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364 | flow.set(e, flo+exc); |
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365 | excess.set(v, excess[v]+exc); |
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366 | exc=0; |
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367 | break; |
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368 | |
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369 | } else { |
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370 | /*A saturating push.*/ |
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371 | |
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372 | flow.set(e, cap); |
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373 | excess.set(v, excess[v]+remcap); |
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374 | exc-=remcap; |
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375 | } |
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376 | } else if ( newlevel > level[v] ){ |
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377 | newlevel = level[v]; |
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378 | } |
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379 | |
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380 | } //for out edges wv |
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381 | |
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382 | |
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383 | if ( exc > 0 ) { |
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384 | InEdgeIt e; |
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385 | for(G.first(e,w); G.valid(e); G.next(e)) { |
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386 | |
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387 | if( flow[e] == 0 ) continue; |
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388 | Node v=G.tail(e); |
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389 | //e=vw |
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390 | |
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391 | if( lev > level[v] ) { |
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392 | /*Push is allowed now*/ |
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393 | |
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394 | if ( excess[v]==0 && v!=t && v!=s ) { |
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395 | int lev_v=level[v]; |
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396 | active[lev_v].push(v); |
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397 | } |
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398 | |
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399 | T flo=flow[e]; |
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400 | |
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401 | if ( flo >= exc ) { |
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402 | /*A nonsaturating push.*/ |
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403 | |
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404 | flow.set(e, flo-exc); |
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405 | excess.set(v, excess[v]+exc); |
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406 | exc=0; |
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407 | break; |
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408 | } else { |
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409 | /*A saturating push.*/ |
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410 | |
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411 | excess.set(v, excess[v]+flo); |
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412 | exc-=flo; |
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413 | flow.set(e,0); |
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414 | } |
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415 | } else if ( newlevel > level[v] ) { |
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416 | newlevel = level[v]; |
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417 | } |
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418 | } //for in edges vw |
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419 | |
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420 | } // if w still has excess after the out edge for cycle |
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421 | |
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422 | excess.set(w, exc); |
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423 | /// push |
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424 | |
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425 | |
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426 | /* |
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427 | Relabel |
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428 | */ |
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429 | |
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430 | |
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431 | if ( exc > 0 ) { |
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432 | //now 'lev' is the old level of w |
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433 | |
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434 | if ( phase ) { |
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435 | level.set(w,++newlevel); |
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436 | active[newlevel].push(w); |
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437 | b=newlevel; |
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438 | } else { |
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439 | //unlacing starts |
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440 | Node right_n=right[w]; |
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441 | Node left_n=left[w]; |
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442 | |
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443 | if ( G.valid(right_n) ) { |
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444 | if ( G.valid(left_n) ) { |
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445 | right.set(left_n, right_n); |
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446 | left.set(right_n, left_n); |
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447 | } else { |
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448 | level_list[lev]=right_n; |
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449 | left.set(right_n, INVALID); |
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450 | } |
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451 | } else { |
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452 | if ( G.valid(left_n) ) { |
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453 | right.set(left_n, INVALID); |
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454 | } else { |
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455 | level_list[lev]=INVALID; |
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456 | } |
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457 | } |
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458 | //unlacing ends |
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459 | |
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460 | if ( !G.valid(level_list[lev]) ) { |
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461 | |
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462 | //gapping starts |
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463 | for (int i=lev; i!=k ; ) { |
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464 | Node v=level_list[++i]; |
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465 | while ( G.valid(v) ) { |
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466 | level.set(v,n); |
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467 | v=right[v]; |
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468 | } |
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469 | level_list[i]=INVALID; |
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470 | if ( !what_heur ) { |
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471 | while ( !active[i].empty() ) { |
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472 | active[i].pop(); //FIXME: ezt szebben kene |
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473 | } |
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474 | } |
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475 | } |
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476 | |
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477 | level.set(w,n); |
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478 | b=lev-1; |
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479 | k=b; |
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480 | //gapping ends |
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481 | |
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482 | } else { |
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483 | |
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484 | if ( newlevel == n ) level.set(w,n); |
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485 | else { |
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486 | level.set(w,++newlevel); |
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487 | active[newlevel].push(w); |
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488 | if ( what_heur ) b=newlevel; |
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489 | if ( k < newlevel ) ++k; //now k=newlevel |
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490 | Node first=level_list[newlevel]; |
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491 | if ( G.valid(first) ) left.set(first,w); |
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492 | right.set(w,first); |
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493 | left.set(w,INVALID); |
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494 | level_list[newlevel]=w; |
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495 | } |
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496 | } |
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497 | |
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498 | |
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499 | ++relabel; |
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500 | if ( relabel >= heur ) { |
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501 | relabel=0; |
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502 | if ( what_heur ) { |
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503 | what_heur=0; |
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504 | heur=heur0; |
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505 | end=false; |
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506 | } else { |
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507 | what_heur=1; |
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508 | heur=heur1; |
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509 | b=k; |
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510 | } |
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511 | } |
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512 | } //phase 0 |
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513 | |
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514 | |
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515 | } // if ( exc > 0 ) |
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516 | |
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517 | |
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518 | } // if stack[b] is nonempty |
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519 | |
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520 | } // while(true) |
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521 | |
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522 | |
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523 | value = excess[t]; |
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524 | /*Max flow value.*/ |
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525 | |
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526 | } //void run() |
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527 | |
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528 | |
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529 | |
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530 | |
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531 | |
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532 | /* |
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533 | Returns the maximum value of a flow. |
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534 | */ |
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535 | |
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536 | T flowValue() { |
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537 | return value; |
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538 | } |
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539 | |
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540 | |
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541 | FlowMap Flow() { |
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542 | return flow; |
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543 | } |
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544 | |
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545 | |
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546 | void Flow(FlowMap& _flow ) { |
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547 | NodeIt v; |
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548 | for(G.first(v) ; G.valid(v); G.next(v)) |
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549 | _flow.set(v,flow[v]); |
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550 | } |
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551 | |
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552 | |
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553 | |
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554 | /* |
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555 | Returns the minimum min cut, by a bfs from s in the residual graph. |
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556 | */ |
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557 | |
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558 | template<typename _CutMap> |
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559 | void minMinCut(_CutMap& M) { |
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560 | |
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561 | std::queue<Node> queue; |
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562 | |
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563 | M.set(s,true); |
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564 | queue.push(s); |
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565 | |
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566 | while (!queue.empty()) { |
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567 | Node w=queue.front(); |
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568 | queue.pop(); |
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569 | |
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570 | OutEdgeIt e; |
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571 | for(G.first(e,w) ; G.valid(e); G.next(e)) { |
---|
572 | Node v=G.head(e); |
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573 | if (!M[v] && flow[e] < capacity[e] ) { |
---|
574 | queue.push(v); |
---|
575 | M.set(v, true); |
---|
576 | } |
---|
577 | } |
---|
578 | |
---|
579 | InEdgeIt f; |
---|
580 | for(G.first(f,w) ; G.valid(f); G.next(f)) { |
---|
581 | Node v=G.tail(f); |
---|
582 | if (!M[v] && flow[f] > 0 ) { |
---|
583 | queue.push(v); |
---|
584 | M.set(v, true); |
---|
585 | } |
---|
586 | } |
---|
587 | } |
---|
588 | } |
---|
589 | |
---|
590 | |
---|
591 | |
---|
592 | /* |
---|
593 | Returns the maximum min cut, by a reverse bfs |
---|
594 | from t in the residual graph. |
---|
595 | */ |
---|
596 | |
---|
597 | template<typename _CutMap> |
---|
598 | void maxMinCut(_CutMap& M) { |
---|
599 | |
---|
600 | std::queue<Node> queue; |
---|
601 | |
---|
602 | M.set(t,true); |
---|
603 | queue.push(t); |
---|
604 | |
---|
605 | while (!queue.empty()) { |
---|
606 | Node w=queue.front(); |
---|
607 | queue.pop(); |
---|
608 | |
---|
609 | |
---|
610 | InEdgeIt e; |
---|
611 | for(G.first(e,w) ; G.valid(e); G.next(e)) { |
---|
612 | Node v=G.tail(e); |
---|
613 | if (!M[v] && flow[e] < capacity[e] ) { |
---|
614 | queue.push(v); |
---|
615 | M.set(v, true); |
---|
616 | } |
---|
617 | } |
---|
618 | |
---|
619 | OutEdgeIt f; |
---|
620 | for(G.first(f,w) ; G.valid(f); G.next(f)) { |
---|
621 | Node v=G.head(f); |
---|
622 | if (!M[v] && flow[f] > 0 ) { |
---|
623 | queue.push(v); |
---|
624 | M.set(v, true); |
---|
625 | } |
---|
626 | } |
---|
627 | } |
---|
628 | |
---|
629 | NodeIt v; |
---|
630 | for(G.first(v) ; G.valid(v); G.next(v)) { |
---|
631 | M.set(v, !M[v]); |
---|
632 | } |
---|
633 | |
---|
634 | } |
---|
635 | |
---|
636 | |
---|
637 | |
---|
638 | template<typename CutMap> |
---|
639 | void minCut(CutMap& M) { |
---|
640 | minMinCut(M); |
---|
641 | } |
---|
642 | |
---|
643 | |
---|
644 | void resetTarget (Node _t) {t=_t;} |
---|
645 | void resetSource (Node _s) {s=_s;} |
---|
646 | |
---|
647 | void resetCap (CapMap _cap) {capacity=_cap;} |
---|
648 | |
---|
649 | void resetFlow (FlowMap _flow, bool _constzero) { |
---|
650 | flow=_flow; |
---|
651 | constzero=_constzero; |
---|
652 | } |
---|
653 | |
---|
654 | |
---|
655 | |
---|
656 | }; |
---|
657 | |
---|
658 | } //namespace lemon |
---|
659 | |
---|
660 | #endif //PREFLOW_H |
---|
661 | |
---|
662 | |
---|
663 | |
---|
664 | |
---|