private static void SolveMinCostFlow()
{
Console.WriteLine("Min Cost Flow Problem");
int numSources = 4;
int numTargets = 4;
int[,] costs = { { 90, 75, 75, 80 },
{ 35, 85, 55, 65 },
{ 125, 95, 90, 105 },
{ 45, 110, 95, 115 } };
int expectedCost = 275;
StarGraph graph = new StarGraph(numSources + numTargets,
numSources * numTargets);
MinCostFlow minCostFlow = new MinCostFlow(graph);
for (int source = 0; source < numSources; ++source)
{
for (int target = 0; target < numTargets; ++target)
{
int arc = graph.AddArc(source, numSources + target);
minCostFlow.SetArcUnitCost(arc, costs[source, target]);
minCostFlow.SetArcCapacity(arc, 1);
}
}
for (int source = 0; source < numSources; ++source)
{
minCostFlow.SetNodeSupply(source, 1);
}
for (int target = 0; target < numTargets; ++target)
{
minCostFlow.SetNodeSupply(numSources + target, -1);
}
Console.WriteLine("Solving min cost flow with " + numSources +
" sources, and " + numTargets + " targets.");
if (minCostFlow.Solve())
{
long totalFlowCost = minCostFlow.GetOptimalCost();
Console.WriteLine("total computed flow cost = " + totalFlowCost +
", expected = " + expectedCost);
}
else
{
Console.WriteLine("No solution found");
}
}
private static void SolveMaxFlow()
{
Console.WriteLine("Max Flow Problem");
int numNodes = 6;
int numArcs = 9;
int[] tails = { 0, 0, 0, 0, 1, 2, 3, 3, 4 };
int[] heads = { 1, 2, 3, 4, 3, 4, 4, 5, 5 };
int[] capacities = { 5, 8, 5, 3, 4, 5, 6, 6, 4 };
int[] expectedFlows = { 4, 4, 2, 0, 4, 4, 0, 6, 4 };
int expectedTotalFlow = 10;
StarGraph graph = new StarGraph(numNodes, numArcs);
MaxFlow maxFlow = new MaxFlow(graph, 0, numNodes - 1);
for (int i = 0; i < numArcs; ++i)
{
int arc = graph.AddArc(tails[i], heads[i]);
maxFlow.SetArcCapacity(arc, capacities[i]);
}
Console.WriteLine("Solving max flow with " + numNodes + " nodes, and " +
numArcs + " arcs, source = 0, sink = " + (numNodes - 1));
if (maxFlow.Solve())
{
long totalFlow = maxFlow.GetOptimalFlow();
Console.WriteLine("total computed flow " + totalFlow +
", expected = " + expectedTotalFlow);
for (int i = 0; i < numArcs; ++i)
{
Console.WriteLine("Arc " + i + " (" + heads[i] + " -> " + tails[i] +
", capacity = " + capacities[i] + ") computed = " +
maxFlow.Flow(i) + ", expected = " + expectedFlows[i]);
}
}
else
{
Console.WriteLine("No solution found");
}
}