99 lines
3.4 KiB
C#
99 lines
3.4 KiB
C#
// Copyright 2010-2022 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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// Minimal example to call the SCIP solver.
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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.ModelBuilder;
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// [END import]
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public class SimpleMipProgramMb
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{
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static void Main()
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{
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// [START model]
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// Create the model builder.
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ModelBuilder model = new ModelBuilder();
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// [END model]
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// [START variables]
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// Create the variables x and y.
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Variable x = model.NewIntVar(0.0, double.PositiveInfinity, "x");
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Variable y = model.NewIntVar(0.0, double.PositiveInfinity, "y");
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// [END variables]
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// [START constraints]
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// x + 7 * y <= 17.5.
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model.Add(x + 7 * y <= 17.5);
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// x <= 3.5.
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LinearConstraint c2 = model.Add(x <= 3.5);
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// [END constraints]
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// [START objective]
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// Maximize x + 10 * y.
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model.Maximize(x + 10 * y);
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// [END objective]
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// [Start clone]
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// Clone the model.
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Console.WriteLine("Cloning the model");
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ModelBuilder modelCopy = model.Clone();
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Variable xCopy = modelCopy.VarFromIndex(x.Index);
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Variable yCopy = modelCopy.VarFromIndex(y.Index);
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Variable zCopy = modelCopy.NewBoolVar("z");
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LinearConstraint c2Copy = modelCopy.ConstraintFromIndex(c2.Index);
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// Add a new constraint.
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LinearConstraint unusedC3Copy = modelCopy.Add(xCopy >= 1);
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// Modify a constraint.
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c2Copy.AddTerm(zCopy, 2.0);
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Console.WriteLine("Number of constraints in the original model = " + model.ConstraintsCount());
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Console.WriteLine("Number of constraints in the cloned model = " + modelCopy.ConstraintsCount());
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// [END clone]
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// [START solver]
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// Create the solver with the SCIP backend and checks it is supported.
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ModelSolver solver = new ModelSolver("SCIP");
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if (!solver.SolverIsSupported()) return;
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// [END solver]
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// [START solve]
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var resultStatus = solver.Solve(modelCopy);
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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 != SolveStatus.OPTIMAL)
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{
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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("Objective value = " + solver.ObjectiveValue);
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Console.WriteLine("x = " + solver.Value(xCopy));
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Console.WriteLine("y = " + solver.Value(yCopy));
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Console.WriteLine("z = " + solver.Value(zCopy));
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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 + " milliseconds");
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// [END advanced]
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}
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}
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// [END program]
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