74 lines
2.4 KiB
C#
74 lines
2.4 KiB
C#
// Copyright 2010-2018 Google LLC
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// [START program]
|
|
using System;
|
|
using Google.OrTools.Graph;
|
|
|
|
public class SimpleMaxFlowProgram
|
|
{
|
|
static void Main()
|
|
{
|
|
// [START data]
|
|
// Define three parallel arrays: start_nodes, end_nodes, and the capacities
|
|
// between each pair. For instance, the arc from node 0 to node 1 has a
|
|
// capacity of 20.
|
|
// From Taha's 'Introduction to Operations Research',
|
|
// example 6.4-2.
|
|
int[] startNodes = {0, 0, 0, 1, 1, 2, 2, 3, 3};
|
|
int[] endNodes = {1, 2, 3, 2, 4, 3, 4, 2, 4};
|
|
int[] capacities = {20, 30, 10, 40, 30, 10, 20, 5, 20};
|
|
// [END data]
|
|
|
|
// [START constraints]
|
|
// Instantiate a SimpleMaxFlow solver.
|
|
MaxFlow maxFlow = new MaxFlow();
|
|
|
|
// Add each arc.
|
|
for (int i = 0; i < startNodes.Length; ++i)
|
|
{
|
|
int arc = maxFlow.AddArcWithCapacity(startNodes[i], endNodes[i],
|
|
capacities[i]);
|
|
if (arc != i) throw new Exception("Internal error");
|
|
}
|
|
// [END constraints]
|
|
|
|
// [START solve]
|
|
// Find the maximum flow between node 0 and node 4.
|
|
MaxFlow.Status solveStatus = maxFlow.Solve(0, 4);
|
|
// [END solve]
|
|
|
|
// [START print_solution]
|
|
if (solveStatus == MaxFlow.Status.OPTIMAL)
|
|
{
|
|
Console.WriteLine("Max. flow: " + maxFlow.OptimalFlow());
|
|
Console.WriteLine("");
|
|
Console.WriteLine(" Arc Flow / Capacity");
|
|
for (int i = 0; i < maxFlow.NumArcs(); ++i)
|
|
{
|
|
Console.WriteLine(maxFlow.Tail(i) + " -> " +
|
|
maxFlow.Head(i) + " " +
|
|
string.Format("{0,3}", maxFlow.Flow(i)) + " / " +
|
|
string.Format("{0,3}", maxFlow.Capacity(i)));
|
|
}
|
|
}
|
|
else
|
|
{
|
|
Console.WriteLine("Solving the max flow problem failed. Solver status: " +
|
|
solveStatus);
|
|
}
|
|
// [END print_solution]
|
|
}
|
|
}
|
|
// [END program]
|