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] }