78 lines
2.5 KiB
C++
78 lines
2.5 KiB
C++
// Copyright 2010-2024 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.
|
|
|
|
// Simple integer programming example
|
|
|
|
#include <cmath>
|
|
#include <iostream>
|
|
#include <limits>
|
|
#include <ostream>
|
|
|
|
#include "absl/status/status.h"
|
|
#include "absl/time/time.h"
|
|
#include "ortools/base/init_google.h"
|
|
#include "ortools/base/logging.h"
|
|
#include "ortools/base/status_macros.h"
|
|
#include "ortools/math_opt/cpp/math_opt.h"
|
|
|
|
namespace {
|
|
|
|
namespace math_opt = ::operations_research::math_opt;
|
|
|
|
constexpr double kInf = std::numeric_limits<double>::infinity();
|
|
|
|
// Model and solve the problem:
|
|
// max x + 10 * y
|
|
// s.t. x + 7 * y <= 17.5
|
|
// x <= 3.5
|
|
// x in {0.0, 1.0, 2.0, ...,
|
|
// y in {0.0, 1.0, 2.0, ...,
|
|
//
|
|
absl::Status Main() {
|
|
math_opt::Model model("Integer programming example");
|
|
|
|
// Variables
|
|
const math_opt::Variable x = model.AddIntegerVariable(0.0, kInf, "x");
|
|
const math_opt::Variable y = model.AddIntegerVariable(0.0, kInf, "y");
|
|
|
|
// Constraints
|
|
model.AddLinearConstraint(x + 7 * y <= 17.5, "c1");
|
|
model.AddLinearConstraint(x <= 3.5, "c2");
|
|
|
|
// Objective
|
|
model.Maximize(x + 10 * y);
|
|
|
|
ASSIGN_OR_RETURN(const math_opt::SolveResult result,
|
|
Solve(model, math_opt::SolverType::kGscip));
|
|
RETURN_IF_ERROR(result.termination.EnsureIsOptimalOrFeasible());
|
|
// A feasible solution is always available on termination reason kOptimal, and
|
|
// kFeasible, but in the later case the solution may be sub-optimal.
|
|
std::cout << "Problem solved in " << result.solve_time() << std::endl;
|
|
std::cout << "Objective value: " << result.objective_value() << std::endl;
|
|
std::cout << "Variable values: [x="
|
|
<< std::round(result.variable_values().at(x))
|
|
<< ", y=" << std::round(result.variable_values().at(y)) << "]"
|
|
<< std::endl;
|
|
return absl::OkStatus();
|
|
}
|
|
} // namespace
|
|
|
|
int main(int argc, char** argv) {
|
|
InitGoogle(argv[0], &argc, &argv, true);
|
|
const absl::Status status = Main();
|
|
if (!status.ok()) {
|
|
LOG(QFATAL) << status;
|
|
}
|
|
return 0;
|
|
}
|