ilp_grb.cpp

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#include <iostream>
 
#include "qbpp.hpp"
#include "qbpp_grb.hpp"
 
int main() {
  // Define variables
  auto x1 = 0 <= qbpp::var_int("x1") <= 5;
  auto x2 = 0 <= qbpp::var_int("x2") <= 4;
  auto x3 = 0 <= qbpp::var_int("x3") <= 3;
  auto x4 = 0 <= qbpp::var_int("x4") <= 6;
 
  // Define the objective function
  auto obj = 6 * x1 + 4 * x2 + 3 * x3 + 5 * x4;
 
  // Define the constraints
  auto c1 = x1 + 2 * x2 + 3 * x3 + 4 * x4;
  auto c2 = 3 * x1 + x2 + 2 * x3 + x4;
 
  // Define QUBO expression
  auto f = -obj + 100 * ((0 <= c1 <= 15) + (0 <= c2 <= 10));
 
  // Simplify the QUBO expression
  f.simplify_as_binary();
 
  // Create a Gurobi model from the QUBO expression
  auto model = qbpp_grb::QuadModel(f);
 
  // Solve the model
  auto sol = model.optimize();
 
  // Print the solution
  std::cout << sol << std::endl;
 
  std::cout << "x1 = " << eval(x1, sol) << std::endl;
  std::cout << "x2 = " << eval(x2, sol) << std::endl;
  std::cout << "x3 = " << eval(x3, sol) << std::endl;
  std::cout << "x4 = " << eval(x4, sol) << std::endl;
  std::cout << "c1 = " << eval(c1, sol) << std::endl;
  std::cout << "c2 = " << eval(c2, sol) << std::endl;
  std::cout << "Objective value = " << eval(obj, sol) << std::endl;
}