1 #ifdef HAVE_CONFIG_H |
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2 #include <config.h> |
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3 #endif |
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4 |
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5 #include<lemon/graph_reader.h> |
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6 #include<lemon/list_graph.h> |
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7 |
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8 |
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9 #ifdef HAVE_GLPK |
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10 #include <lemon/lp_glpk.h> |
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11 #elif HAVE_CPLEX |
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12 #include <lemon/lp_cplex.h> |
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13 #endif |
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14 |
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15 using namespace lemon; |
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16 |
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17 #ifdef HAVE_GLPK |
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18 typedef LpGlpk LpDefault; |
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19 #elif HAVE_CPLEX |
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20 typedef LpCplex LpDefault; |
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21 #endif |
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22 |
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23 |
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24 template<class G,class C> |
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25 double maxFlow(const G &g,const C &cap,typename G::Node s,typename G::Node t) |
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26 { |
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27 LpDefault lp; |
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28 |
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29 typedef G Graph; |
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30 typedef typename G::Node Node; |
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31 typedef typename G::NodeIt NodeIt; |
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32 typedef typename G::Edge Edge; |
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33 typedef typename G::EdgeIt EdgeIt; |
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34 typedef typename G::OutEdgeIt OutEdgeIt; |
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35 typedef typename G::InEdgeIt InEdgeIt; |
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36 |
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37 typename G::template EdgeMap<LpDefault::Col> x(g); |
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38 lp.addColSet(x); |
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39 |
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40 for(EdgeIt e(g);e!=INVALID;++e) { |
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41 lp.colUpperBound(x[e],cap[e]); |
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42 lp.colLowerBound(x[e],0); |
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43 } |
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44 |
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45 for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) { |
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46 LpDefault::Expr ex; |
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47 for(InEdgeIt e(g,n);e!=INVALID;++e) ex+=x[e]; |
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48 for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e]; |
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49 lp.addRow(ex==0); |
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50 } |
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51 { |
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52 LpDefault::Expr ex; |
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53 for(InEdgeIt e(g,t);e!=INVALID;++e) ex+=x[e]; |
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54 for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e]; |
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55 lp.setObj(ex); |
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56 } |
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57 lp.max(); |
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58 |
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59 #ifdef HAVE_GLPK |
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60 lp.presolver(true); |
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61 lp.messageLevel(3); |
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62 #endif |
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63 |
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64 lp.solve(); |
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65 |
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66 return lp.primalValue(); |
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67 } |
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68 |
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69 int main() |
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70 { |
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71 ListGraph g; |
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72 ListGraph::Node s; |
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73 ListGraph::Node t; |
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74 |
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75 ListGraph::EdgeMap<double> cap(g); |
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76 |
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77 GraphReader<ListGraph> reader(std::cin,g); |
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78 reader.readNode("source",s).readNode("target",t) |
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79 .readEdgeMap("capacity",cap).run(); |
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80 |
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81 // std::ifstream file("../test/preflow_"); |
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82 // readDimacs(file, g, cap, s, t); |
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83 |
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84 std::cout << "Max flow value = " << maxFlow(g,cap,s,t) << std::endl; |
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85 |
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86 } |
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