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Sample code of using Network Simplex in Lemon for Min Cost Flow problem.
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| #include <iostream> | |
| #include <lemon/smart_graph.h> | |
| #include <lemon/network_simplex.h> | |
| using namespace lemon; | |
| using namespace std; | |
| using Weight = int; | |
| using Capacity = int; | |
| using Graph = SmartDigraph; | |
| using Node = Graph::Node; | |
| using Arc = Graph::Arc; | |
| template<typename ValueType> | |
| using ArcMap = SmartDigraph::ArcMap<ValueType>; | |
| using NS = NetworkSimplex<SmartDigraph, Capacity, Weight>; | |
| int main() { | |
| Graph g; | |
| Node u = g.addNode(); | |
| Node v = g.addNode(); | |
| Arc a = g.addArc(u, v); | |
| Arc b = g.addArc(u, v); | |
| ArcMap<Weight> weights(g); | |
| weights[a] = 5; | |
| weights[b] = 2; | |
| ArcMap<Capacity> capacities(g); | |
| capacities[a] = 10; | |
| capacities[b] = 5; | |
| NS ns(g); | |
| ns.costMap(weights).upperMap(capacities).stSupply(u, v, 12); | |
| ArcMap<Capacity> flows(g); | |
| NS::ProblemType status = ns.run(); | |
| switch (status) { | |
| case NS::INFEASIBLE: | |
| cerr << "insufficient flow" << endl; | |
| break; | |
| case NS::OPTIMAL: | |
| ns.flowMap(flows); | |
| cerr << "flow[a]=" << ns.flow(a) << " flow[b]=" << flows[b] << endl; | |
| cerr << "cost=" << ns.totalCost() << endl; | |
| break; | |
| case NS::UNBOUNDED: | |
| cerr << "infinite flow" << endl; | |
| break; | |
| default: | |
| break; | |
| } | |
| return 0; | |
| } |
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