/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */ /* * Main authors: * Christian Schulte <schulte@gecode.org> * * Copyright: * Christian Schulte, 2001 * * Last modified: * $Date: 2011-08-29 20:13:11 +1000 (Mon, 29 Aug 2011) $ by $Author: schulte $ * $Revision: 12357 $ * * This file is part of Gecode, the generic constraint * development environment: * http://www.gecode.org * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. * */ #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 MinimizeScript { protected: /// Array for ruler marks IntVarArray m; public: /// Search variants enum { SEARCH_BAB, ///< Use branch and bound to optimize SEARCH_RESTART ///< Use restart to optimize }; /// Actual model GolombRuler(const SizeOptions& 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.icl()); // 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(bool share, GolombRuler& s) : MinimizeScript(share,s) { m.update(*this, share, s.m); } /// Copy during cloning virtual Space* copy(bool share) { return new GolombRuler(share,*this); } }; /** \brief Main-function * \relates GolombRuler */ int main(int argc, char* argv[]) { SizeOptions opt("GolombRuler"); opt.solutions(0); opt.size(10); opt.icl(ICL_BND); opt.search(GolombRuler::SEARCH_BAB); opt.search(GolombRuler::SEARCH_BAB, "bab"); opt.search(GolombRuler::SEARCH_RESTART, "restart"); opt.parse(argc,argv); if (opt.size() > 0) switch (opt.search()) { case GolombRuler::SEARCH_BAB: MinimizeScript::run<GolombRuler,BAB,SizeOptions>(opt); break; case GolombRuler::SEARCH_RESTART: MinimizeScript::run<GolombRuler,Restart,SizeOptions>(opt); break; } return 0; } // STATISTICS: example-any