SimpleMipProgram.cs

Go to the documentation of this file.

// 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]
// [START import]
using System;
using Google.OrTools.LinearSolver;
// [END import]
 
public class SimpleMipProgram
{
  static void Main()
  {
    // [START solver]
    // Create the linear solver with the CBC backend.
    Solver solver = Solver.CreateSolver("SimpleMipProgram", "CBC_MIXED_INTEGER_PROGRAMMING");
    // [END solver]
 
    // [START variables]
    // x and y are integer non-negative variables.
    Variable x = solver.MakeIntVar(0.0, double.PositiveInfinity, "x");
    Variable y = solver.MakeIntVar(0.0, double.PositiveInfinity, "y");
 
    Console.WriteLine("Number of variables = " + solver.NumVariables());
    // [END variables]
 
    // [START constraints]
    // x + 7 * y <= 17.5.
    solver.Add(x + 7 * y <= 17.5);
 
    // x <= 3.5.
    solver.Add(x <= 3.5);
 
    Console.WriteLine("Number of constraints = " + solver.NumConstraints());
    // [END constraints]
 
    // [START objective]
    // Maximize x + 10 * y.
    solver.Maximize(x + 10 * y);
    // [END objective]
 
    // [START solve]
    Solver.ResultStatus resultStatus = solver.Solve();
    // Check that the problem has an optimal solution.
    if (resultStatus != Solver.ResultStatus.OPTIMAL)
    {
      Console.WriteLine("The problem does not have an optimal solution!");
      return;
    }
    // [END solve]
 
    // [START print_solution]
    Console.WriteLine("Solution:");
    Console.WriteLine("Objective value = " + solver.Objective().Value());
    Console.WriteLine("x = " + x.SolutionValue());
    Console.WriteLine("y = " + y.SolutionValue());
    // [END print_solution]
 
    // [START advanced]
    Console.WriteLine("\nAdvanced usage:");
    Console.WriteLine("Problem solved in " + solver.WallTime() + " milliseconds");
    Console.WriteLine("Problem solved in " + solver.Iterations() + " iterations");
    Console.WriteLine("Problem solved in " + solver.Nodes() + " branch-and-bound nodes");
    // [END advanced]
  }
}
// [END program]