109 lines
3.4 KiB
C#
109 lines
3.4 KiB
C#
// Copyright 2010-2018 Google LLC
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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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// [START program]
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// [START import]
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using System;
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using Google.OrTools.LinearSolver;
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// [END import]
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// [START program_part1]
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public class MipVarArray {
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// [START data_model]
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class DataModel {
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public double[, ] ConstraintCoeffs = {
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{5, 7, 9, 2, 1},
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{18, 4, -9, 10, 12},
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{4, 7, 3, 8, 5},
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{5, 13, 16, 3, -7},
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};
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public double[] Bounds = {250, 285, 211, 315};
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public double[] ObjCoeffs = {7, 8, 2, 9, 6};
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public int NumVars = 5;
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public int NumConstraints = 4;
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}
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// [END data_model]
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public static void Main() {
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// [START data]
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DataModel data = new DataModel();
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// [END data]
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// [END program_part1]
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// [START solver]
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// Create the linear solver with the SCIP backend.
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Solver solver = Solver.CreateSolver("SCIP");
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// [END solver]
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// [START program_part2]
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// [START variables]
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Variable[] x = new Variable[data.NumVars];
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for (int j = 0; j < data.NumVars; j++) {
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x[j] = solver.MakeIntVar(0.0, double.PositiveInfinity, $"x_{j}");
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}
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Console.WriteLine("Number of variables = " + solver.NumVariables());
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// [END variables]
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// [START constraints]
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for (int i = 0; i < data.NumConstraints; ++i) {
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Constraint constraint = solver.MakeConstraint(0, data.Bounds[i], "");
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for (int j = 0; j < data.NumVars; ++j) {
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constraint.SetCoefficient(x[j], data.ConstraintCoeffs[i, j]);
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}
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}
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Console.WriteLine("Number of constraints = " + solver.NumConstraints());
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// [END constraints]
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// [START objective]
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Objective objective = solver.Objective();
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for (int j = 0; j < data.NumVars; ++j) {
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objective.SetCoefficient(x[j], data.ObjCoeffs[j]);
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}
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objective.SetMaximization();
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// [END objective]
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// [START solve]
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Solver.ResultStatus resultStatus = solver.Solve();
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// [END solve]
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// [START print_solution]
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// Check that the problem has an optimal solution.
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if (resultStatus != Solver.ResultStatus.OPTIMAL) {
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Console.WriteLine("The problem does not have an optimal solution!");
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return;
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}
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Console.WriteLine("Solution:");
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Console.WriteLine("Optimal objective value = " +
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solver.Objective().Value());
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for (int j = 0; j < data.NumVars; ++j) {
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Console.WriteLine("x[" + j + "] = " +
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x [j]
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.SolutionValue());
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}
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// [END print_solution]
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// [START advanced]
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Console.WriteLine("\nAdvanced usage:");
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Console.WriteLine("Problem solved in " + solver.WallTime() +
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" milliseconds");
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Console.WriteLine("Problem solved in " + solver.Iterations() +
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" iterations");
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Console.WriteLine("Problem solved in " + solver.Nodes() +
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" branch-and-bound nodes");
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// [END advanced]
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}
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}
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// [END program_part2]
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// [END program]
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