alpar@1309: #include<lemon/lp_glpk.h>
alpar@1309: #include<lemon/graph_reader.h>
alpar@1309: #include<lemon/list_graph.h>
alpar@1309: 
alpar@1309: using namespace lemon;
alpar@1309: 
alpar@1309: template<class G,class C>
alpar@1309: double maxFlow(const G &g,const C &cap,typename G::Node s,typename G::Node t)
alpar@1309: {
alpar@1309:   LpGlpk lp;
alpar@1309:   
alpar@1309:   typedef G Graph;
alpar@1309:   typedef typename G::Node Node;
alpar@1309:   typedef typename G::NodeIt NodeIt;
alpar@1309:   typedef typename G::Edge Edge;
alpar@1309:   typedef typename G::EdgeIt EdgeIt;
alpar@1309:   typedef typename G::OutEdgeIt OutEdgeIt;
alpar@1309:   typedef typename G::InEdgeIt InEdgeIt;
alpar@1309:   
alpar@1309:   typename G::template EdgeMap<LpGlpk::Col> x(g);
alpar@1309:   lp.addColSet(x);
alpar@1309:   
alpar@1309:   for(EdgeIt e(g);e!=INVALID;++e) {
alpar@1309:     lp.colUpperBound(x[e],cap[e]);
alpar@1309:     lp.colLowerBound(x[e],0);
alpar@1309:   }
alpar@1309: 
alpar@1309:   for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) {
alpar@1309:     LpGlpk::Expr ex;
alpar@1309:     for(InEdgeIt  e(g,n);e!=INVALID;++e) ex+=x[e];
alpar@1309:     for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e];
alpar@1309:     lp.addRow(ex==0);
alpar@1309:   }
alpar@1309:   {
alpar@1309:     LpGlpk::Expr ex;
alpar@1309:     for(InEdgeIt  e(g,t);e!=INVALID;++e) ex+=x[e];
alpar@1309:     for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e];
alpar@1309:     lp.setObj(ex);
alpar@1309:   }
alpar@1322:   lp.max();
alpar@1326: 
alpar@1326:   lp.presolver(true);
alpar@1326:   
alpar@1326:   lp.messageLevel(3);
alpar@1326: 
alpar@1309:   lp.solve();
alpar@1309: 
alpar@1322:   return lp.primalValue();
alpar@1309: }
alpar@1309: 
alpar@1309: int main() 
alpar@1309: {
alpar@1309:   ListGraph g;
alpar@1322:   ListGraph::Node s;
alpar@1322:   ListGraph::Node t;
alpar@1322:   
alpar@1309:   ListGraph::EdgeMap<double> cap(g);
alpar@1309:   
alpar@1309:   GraphReader<ListGraph> reader(std::cin,g);
alpar@1322:   reader.addNode("source",s).addNode("target",t)
alpar@1322:     .addEdgeMap("capacity",cap).run();
alpar@1309:   
alpar@1322:   // std::ifstream file("../test/preflow_");
alpar@1322: //   readDimacs(file, g, cap, s, t);
alpar@1322: 
alpar@1322:   std::cout << "Max flow value = " << maxFlow(g,cap,s,t) << std::endl;
alpar@1309: 
alpar@1309: }