public void PrintNetworkFlowSolution(MinCostFlow networkFlowSolution)
{
long optimalCost = networkFlowSolution.OptimalCost();
Console.WriteLine("Minimum cost: " + optimalCost);
Console.WriteLine("");
Console.WriteLine(" Edge Flow / Capacity Cost");
for (int i = 0; i < numArcs; ++i)
{
long cost = networkFlowSolution.Flow(i) * networkFlowSolution.UnitCost(i);
Console.WriteLine(networkFlowSolution.Tail(i) + " -> " +
networkFlowSolution.Head(i) + " " +
string.Format("{0,3}", networkFlowSolution.Flow(i)) + " / " +
string.Format("{0,3}", networkFlowSolution.Capacity(i)) + " " +
string.Format("{0,3}", cost));
}
}
static void Main()
{
// [START data]
// Define four parallel arrays: sources, destinations, capacities, and unit costs
// between each pair. For instance, the arc from node 0 to node 1 has a
// capacity of 15.
// Problem taken From Taha's 'Introduction to Operations Research',
// example 6.4-2.
int[] startNodes = { 0, 0, 1, 1, 1, 2, 2, 3, 4 };
int[] endNodes = { 1, 2, 2, 3, 4, 3, 4, 4, 2 };
int[] capacities = { 15, 8, 20, 4, 10, 15, 4, 20, 5 };
int[] unitCosts = { 4, 4, 2, 2, 6, 1, 3, 2, 3 };
// Define an array of supplies at each node.
int[] supplies = { 20, 0, 0, -5, -15 };
// [END data]
// [START constraints]
// Instantiate a SimpleMinCostFlow solver.
MinCostFlow minCostFlow = new MinCostFlow();
// Add each arc.
for (int i = 0; i < startNodes.Length; ++i)
{
int arc =
minCostFlow.AddArcWithCapacityAndUnitCost(startNodes[i], endNodes[i], capacities[i], unitCosts[i]);
if (arc != i)
{
throw new Exception("Internal error");
}
}
// Add node supplies.
for (int i = 0; i < supplies.Length; ++i)
{
minCostFlow.SetNodeSupply(i, supplies[i]);
}
// [END constraints]
// [START solve]
// Find the min cost flow.
MinCostFlow.Status solveStatus = minCostFlow.Solve();
// [END solve]
// [START print_solution]
if (solveStatus == MinCostFlow.Status.OPTIMAL)
{
Console.WriteLine("Minimum cost: " + minCostFlow.OptimalCost());
Console.WriteLine("");
Console.WriteLine(" Edge Flow / Capacity Cost");
for (int i = 0; i < minCostFlow.NumArcs(); ++i)
{
long cost = minCostFlow.Flow(i) * minCostFlow.UnitCost(i);
Console.WriteLine(minCostFlow.Tail(i) + " -> " + minCostFlow.Head(i) + " " +
string.Format("{0,3}", minCostFlow.Flow(i)) + " / " +
string.Format("{0,3}", minCostFlow.Capacity(i)) + " " +
string.Format("{0,3}", cost));
}
}
else
{
Console.WriteLine("Solving the min cost flow problem failed. Solver status: " + solveStatus);
}
// [END print_solution]
}
