106 lines
3.5 KiB
C#
106 lines
3.5 KiB
C#
// Copyright 2010-2011 Google
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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using System;
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using Google.OrTools.Graph;
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public class CsFlow
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{
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private static void SolveMinCostFlow()
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{
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Console.WriteLine("Min Cost Flow Problem");
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int numSources = 4;
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int numTargets = 4;
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int[,] costs = { {90, 75, 75, 80},
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{35, 85, 55, 65},
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{125, 95, 90, 105},
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{45, 110, 95, 115} };
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int expectedCost = 275;
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StarGraph graph = new StarGraph(numSources + numTargets,
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numSources * numTargets);
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MinCostFlow minCostFlow = new MinCostFlow(graph);
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for (int source = 0; source < numSources; ++source)
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{
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for (int target = 0; target < numTargets; ++target) {
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int arc = graph.AddArc(source, numSources + target);
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minCostFlow.SetArcUnitCost(arc, costs[source, target]);
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minCostFlow.SetArcCapacity(arc, 1);
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}
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}
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for (int source = 0; source < numSources; ++source)
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{
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minCostFlow.SetNodeSupply(source, 1);
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}
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for (int target = 0; target < numTargets; ++target)
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{
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minCostFlow.SetNodeSupply(numSources + target, -1);
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}
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Console.WriteLine("Solving min cost flow with " + numSources +
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" sources, and " + numTargets + " targets.");
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if (minCostFlow.Solve())
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{
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long totalFlowCost = minCostFlow.GetOptimalCost();
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Console.WriteLine("total computed flow cost = " + totalFlowCost +
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", expected = " + expectedCost);
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}
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else
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{
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Console.WriteLine("No solution found");
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}
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}
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private static void SolveMaxFlow()
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{
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Console.WriteLine("Max Flow Problem");
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int numNodes = 6;
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int numArcs = 9;
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int[] tails = {0, 0, 0, 0, 1, 2, 3, 3, 4};
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int[] heads = {1, 2, 3, 4, 3, 4, 4, 5, 5};
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int[] capacities = {5, 8, 5, 3, 4, 5, 6, 6, 4};
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int[] expectedFlows = {4, 4, 2, 0, 4, 4, 0, 6, 4};
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int expectedTotalFlow = 10;
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StarGraph graph = new StarGraph(numNodes, numArcs);
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MaxFlow maxFlow = new MaxFlow(graph, 0, numNodes - 1);
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for (int i = 0; i < numArcs; ++i)
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{
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int arc = graph.AddArc(tails[i], heads[i]);
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maxFlow.SetArcCapacity(arc, capacities[i]);
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}
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Console.WriteLine("Solving max flow with " + numNodes + " nodes, and " +
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numArcs + " arcs, source = 0, sink = " + (numNodes - 1));
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if (maxFlow.Solve())
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{
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long totalFlow = maxFlow.GetOptimalFlow();
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Console.WriteLine("total computed flow " + totalFlow +
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", expected = " + expectedTotalFlow);
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for (int i = 0; i < numArcs; ++i)
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{
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Console.WriteLine("Arc " + i + " (" + heads[i] + " -> " + tails[i] +
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", capacity = " + capacities[i] + ") computed = " +
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maxFlow.Flow(i) + ", expected = " + expectedFlows[i]);
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}
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}
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else
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{
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Console.WriteLine("No solution found");
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}
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}
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static void Main()
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{
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SolveMinCostFlow();
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SolveMaxFlow();
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}
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}
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