1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2008 |
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6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 | * |
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9 | * Permission to use, modify and distribute this software is granted |
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10 | * provided that this copyright notice appears in all copies. For |
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11 | * precise terms see the accompanying LICENSE file. |
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12 | * |
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13 | * This software is provided "AS IS" with no warranty of any kind, |
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14 | * express or implied, and with no claim as to its suitability for any |
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15 | * purpose. |
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16 | * |
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17 | */ |
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18 | |
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19 | #include <fstream> |
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20 | #include <string> |
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21 | |
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22 | #include "test_tools.h" |
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23 | #include <lemon/smart_graph.h> |
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24 | #include <lemon/dimacs.h> |
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25 | #include <lemon/preflow.h> |
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26 | #include <lemon/concepts/graph.h> |
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27 | #include <lemon/concepts/maps.h> |
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28 | |
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29 | using namespace lemon; |
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30 | |
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31 | void checkPreflow() |
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32 | { |
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33 | typedef int VType; |
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34 | typedef concepts::Graph Graph; |
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35 | |
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36 | typedef Graph::Node Node; |
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37 | typedef Graph::Edge Edge; |
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38 | typedef concepts::ReadMap<Edge,VType> CapMap; |
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39 | typedef concepts::ReadWriteMap<Edge,VType> FlowMap; |
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40 | typedef concepts::WriteMap<Node,bool> CutMap; |
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41 | |
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42 | Graph g; |
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43 | Node n; |
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44 | Edge e; |
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45 | CapMap cap; |
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46 | FlowMap flow; |
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47 | CutMap cut; |
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48 | |
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49 | Preflow<Graph, CapMap>::DefFlowMap<FlowMap>::Create preflow_test(g,cap,n,n); |
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50 | |
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51 | preflow_test.capacityMap(cap); |
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52 | flow = preflow_test.flowMap(); |
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53 | preflow_test.flowMap(flow); |
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54 | preflow_test.source(n); |
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55 | preflow_test.target(n); |
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56 | |
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57 | preflow_test.init(); |
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58 | preflow_test.flowInit(cap); |
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59 | preflow_test.startFirstPhase(); |
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60 | preflow_test.startSecondPhase(); |
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61 | preflow_test.run(); |
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62 | preflow_test.runMinCut(); |
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63 | |
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64 | preflow_test.flowValue(); |
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65 | preflow_test.minCut(n); |
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66 | preflow_test.minCutMap(cut); |
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67 | preflow_test.flow(e); |
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68 | |
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69 | } |
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70 | |
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71 | int cutValue (const SmartGraph& g, |
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72 | const SmartGraph::NodeMap<bool>& cut, |
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73 | const SmartGraph::EdgeMap<int>& cap) { |
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74 | |
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75 | int c=0; |
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76 | for(SmartGraph::EdgeIt e(g); e!=INVALID; ++e) { |
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77 | if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e]; |
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78 | } |
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79 | return c; |
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80 | } |
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81 | |
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82 | bool checkFlow(const SmartGraph& g, |
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83 | const SmartGraph::EdgeMap<int>& flow, |
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84 | const SmartGraph::EdgeMap<int>& cap, |
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85 | SmartGraph::Node s, SmartGraph::Node t) { |
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86 | |
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87 | for (SmartGraph::EdgeIt e(g); e != INVALID; ++e) { |
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88 | if (flow[e] < 0 || flow[e] > cap[e]) return false; |
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89 | } |
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90 | |
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91 | for (SmartGraph::NodeIt n(g); n != INVALID; ++n) { |
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92 | if (n == s || n == t) continue; |
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93 | int sum = 0; |
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94 | for (SmartGraph::OutEdgeIt e(g, n); e != INVALID; ++e) { |
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95 | sum += flow[e]; |
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96 | } |
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97 | for (SmartGraph::InEdgeIt e(g, n); e != INVALID; ++e) { |
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98 | sum -= flow[e]; |
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99 | } |
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100 | if (sum != 0) return false; |
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101 | } |
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102 | return true; |
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103 | } |
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104 | |
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105 | int main() { |
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106 | |
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107 | typedef SmartGraph Graph; |
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108 | |
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109 | typedef Graph::Node Node; |
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110 | typedef Graph::NodeIt NodeIt; |
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111 | typedef Graph::EdgeIt EdgeIt; |
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112 | typedef Graph::EdgeMap<int> CapMap; |
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113 | typedef Graph::EdgeMap<int> FlowMap; |
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114 | typedef Graph::NodeMap<bool> CutMap; |
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115 | |
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116 | typedef Preflow<Graph, CapMap> PType; |
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117 | |
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118 | std::string f_name; |
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119 | if( getenv("srcdir") ) |
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120 | f_name = std::string(getenv("srcdir")); |
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121 | else f_name = "."; |
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122 | f_name += "/test/preflow_graph.dim"; |
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123 | |
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124 | std::ifstream file(f_name.c_str()); |
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125 | |
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126 | check(file, "Input file '" << f_name << "' not found."); |
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127 | |
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128 | Graph g; |
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129 | Node s, t; |
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130 | CapMap cap(g); |
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131 | readDimacs(file, g, cap, s, t); |
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132 | |
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133 | PType preflow_test(g, cap, s, t); |
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134 | preflow_test.run(); |
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135 | |
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136 | check(checkFlow(g, preflow_test.flowMap(), cap, s, t), |
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137 | "The flow is not feasible."); |
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138 | |
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139 | CutMap min_cut(g); |
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140 | preflow_test.minCutMap(min_cut); |
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141 | int min_cut_value=cutValue(g,min_cut,cap); |
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142 | |
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143 | check(preflow_test.flowValue() == min_cut_value, |
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144 | "The max flow value is not equal to the three min cut values."); |
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145 | |
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146 | FlowMap flow(g); |
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147 | flow = preflow_test.flowMap(); |
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148 | |
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149 | int flow_value=preflow_test.flowValue(); |
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150 | |
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151 | for(EdgeIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e]; |
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152 | preflow_test.flowInit(flow); |
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153 | preflow_test.startFirstPhase(); |
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154 | |
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155 | CutMap min_cut1(g); |
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156 | preflow_test.minCutMap(min_cut1); |
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157 | min_cut_value=cutValue(g,min_cut1,cap); |
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158 | |
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159 | check(preflow_test.flowValue() == min_cut_value && |
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160 | min_cut_value == 2*flow_value, |
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161 | "The max flow value or the min cut value is wrong."); |
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162 | |
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163 | preflow_test.startSecondPhase(); |
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164 | |
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165 | check(checkFlow(g, preflow_test.flowMap(), cap, s, t), |
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166 | "The flow is not feasible."); |
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167 | |
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168 | CutMap min_cut2(g); |
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169 | preflow_test.minCutMap(min_cut2); |
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170 | min_cut_value=cutValue(g,min_cut2,cap); |
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171 | |
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172 | check(preflow_test.flowValue() == min_cut_value && |
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173 | min_cut_value == 2*flow_value, |
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174 | "The max flow value or the three min cut values were not doubled"); |
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175 | |
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176 | |
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177 | preflow_test.flowMap(flow); |
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178 | |
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179 | NodeIt tmp1(g,s); |
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180 | ++tmp1; |
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181 | if ( tmp1 != INVALID ) s=tmp1; |
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182 | |
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183 | NodeIt tmp2(g,t); |
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184 | ++tmp2; |
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185 | if ( tmp2 != INVALID ) t=tmp2; |
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186 | |
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187 | preflow_test.source(s); |
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188 | preflow_test.target(t); |
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189 | |
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190 | preflow_test.run(); |
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191 | |
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192 | CutMap min_cut3(g); |
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193 | preflow_test.minCutMap(min_cut3); |
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194 | min_cut_value=cutValue(g,min_cut3,cap); |
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195 | |
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196 | |
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197 | check(preflow_test.flowValue() == min_cut_value, |
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198 | "The max flow value or the three min cut values are incorrect."); |
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199 | |
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200 | return 0; |
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201 | } |
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