1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/demo/lp_maxflow_demo.cc	Fri Apr 15 20:46:18 2005 +0000
     1.3 @@ -0,0 +1,68 @@
     1.4 +#include<lemon/lp_glpk.h>
     1.5 +#include<lemon/graph_reader.h>
     1.6 +#include<lemon/list_graph.h>
     1.7 +
     1.8 +using namespace lemon;
     1.9 +
    1.10 +template<class G,class C>
    1.11 +double maxFlow(const G &g,const C &cap,typename G::Node s,typename G::Node t)
    1.12 +{
    1.13 +  LpGlpk lp;
    1.14 +  
    1.15 +  typedef G Graph;
    1.16 +  typedef typename G::Node Node;
    1.17 +  typedef typename G::NodeIt NodeIt;
    1.18 +  typedef typename G::Edge Edge;
    1.19 +  typedef typename G::EdgeIt EdgeIt;
    1.20 +  typedef typename G::OutEdgeIt OutEdgeIt;
    1.21 +  typedef typename G::InEdgeIt InEdgeIt;
    1.22 +  
    1.23 +  typename G::template EdgeMap<LpGlpk::Col> x(g);
    1.24 +  lp.addColSet(x);
    1.25 +  
    1.26 +  for(EdgeIt e(g);e!=INVALID;++e) {
    1.27 +    lp.colUpperBound(x[e],cap[e]);
    1.28 +    lp.colLowerBound(x[e],0);
    1.29 +  }
    1.30 +
    1.31 +  for(NodeIt n(g);n!=INVALID;++n) if(n!=s&&n!=t) {
    1.32 +    LpGlpk::Expr ex;
    1.33 +    for(InEdgeIt  e(g,n);e!=INVALID;++e) ex+=x[e];
    1.34 +    for(OutEdgeIt e(g,n);e!=INVALID;++e) ex-=x[e];
    1.35 +    lp.addRow(ex==0);
    1.36 +  }
    1.37 +  {
    1.38 +    LpGlpk::Expr ex;
    1.39 +    for(InEdgeIt  e(g,t);e!=INVALID;++e) ex+=x[e];
    1.40 +    for(OutEdgeIt e(g,t);e!=INVALID;++e) ex-=x[e];
    1.41 +    lp.setObj(ex);
    1.42 +  }
    1.43 +  lp.max();
    1.44 +
    1.45 +  lp.presolver(true);
    1.46 +  
    1.47 +  lp.messageLevel(3);
    1.48 +
    1.49 +  lp.solve();
    1.50 +
    1.51 +  return lp.primalValue();
    1.52 +}
    1.53 +
    1.54 +int main() 
    1.55 +{
    1.56 +  ListGraph g;
    1.57 +  ListGraph::Node s;
    1.58 +  ListGraph::Node t;
    1.59 +  
    1.60 +  ListGraph::EdgeMap<double> cap(g);
    1.61 +  
    1.62 +  GraphReader<ListGraph> reader(std::cin,g);
    1.63 +  reader.addNode("source",s).addNode("target",t)
    1.64 +    .addEdgeMap("capacity",cap).run();
    1.65 +  
    1.66 +  // std::ifstream file("../test/preflow_");
    1.67 +//   readDimacs(file, g, cap, s, t);
    1.68 +
    1.69 +  std::cout << "Max flow value = " << maxFlow(g,cap,s,t) << std::endl;
    1.70 +
    1.71 +}