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#include <gecode/driver.hh>#include <gecode/int.hh>#include <gecode/minimodel.hh>
#include <iomanip>
using namespace Gecode;
/** * \brief %Example: Finding optimal %Golomb rulers * * The script makes use of two lower bounds taken from: * Barbara Smith, Kostas Stergiou, Toby Walsh, * Modelling the Golomb Ruler Problem. * In IJCAI 99 Workshop on Non-binary Constraints, * 1999. * * See also problem 6 at http://www.csplib.org/. * * The upper bound used is from the trivial construction where * distances between consecutive marks are increasing powers of two. * * Note that "Modeling and Programming with Gecode" uses this example * as a case study. * * \ingroup Example * */class GolombRuler : public IntMinimizeScript {protected: /// Array for ruler marks IntVarArray m;public: /// Actual model GolombRuler(const SizeOptions& opt) : IntMinimizeScript(opt), m(*this,opt.size(),0, (opt.size() < 31) ? (1 << (opt.size()-1))-1 : Int::Limits::max) {
// Assume first mark to be zero rel(*this, m[0], IRT_EQ, 0);
// Order marks rel(*this, m, IRT_LE);
// Number of marks and differences const int n = m.size(); const int n_d = (n*n-n)/2;
// Array of differences IntVarArgs d(n_d);
// Setup difference constraints for (int k=0, i=0; i<n-1; i++) for (int j=i+1; j<n; j++, k++) // d[k] is m[j]-m[i] and must be at least sum of first j-i integers rel(*this, d[k] = expr(*this, m[j]-m[i]), IRT_GQ, (j-i)*(j-i+1)/2);
distinct(*this, d, opt.ipl());
// Symmetry breaking if (n > 2) rel(*this, d[0], IRT_LE, d[n_d-1]);
branch(*this, m, INT_VAR_NONE(), INT_VAL_MIN()); }
/// Return cost virtual IntVar cost(void) const { return m[m.size()-1]; }
/// Print solution virtual void print(std::ostream& os) const { os << "\tm[" << m.size() << "] = " << m << std::endl; }
/// Constructor for cloning \a s GolombRuler(GolombRuler& s) : IntMinimizeScript(s) { m.update(*this, s.m); } /// Copy during cloning virtual Space* copy(void) { return new GolombRuler(*this); }};
/** \brief Main-function * \relates GolombRuler */intmain(int argc, char* argv[]) { SizeOptions opt("GolombRuler"); opt.solutions(0); opt.size(10); opt.ipl(IPL_BND); opt.parse(argc,argv); if (opt.size() > 0) IntMinimizeScript::run<GolombRuler,BAB,SizeOptions>(opt); return 0;}
// STATISTICS: example-any