142 lines
3.8 KiB
C++
142 lines
3.8 KiB
C++
/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
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/*
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* Main authors:
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* Christian Schulte <schulte@gecode.org>
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*
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* Copyright:
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* Christian Schulte, 2001
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*
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* This file is part of Gecode, the generic constraint
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* development environment:
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* http://www.gecode.org
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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#include <gecode/driver.hh>
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#include <gecode/int.hh>
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#include <gecode/minimodel.hh>
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#include <iomanip>
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using namespace Gecode;
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/**
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* \brief %Example: Finding optimal %Golomb rulers
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*
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* The script makes use of two lower bounds taken from:
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* Barbara Smith, Kostas Stergiou, Toby Walsh,
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* Modelling the Golomb Ruler Problem.
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* In IJCAI 99 Workshop on Non-binary Constraints,
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* 1999.
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*
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* See also problem 6 at http://www.csplib.org/.
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*
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* The upper bound used is from the trivial construction where
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* distances between consecutive marks are increasing powers of two.
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*
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* Note that "Modeling and Programming with Gecode" uses this example
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* as a case study.
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*
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* \ingroup Example
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*
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*/
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class GolombRuler : public IntMinimizeScript {
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protected:
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/// Array for ruler marks
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IntVarArray m;
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public:
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/// Actual model
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GolombRuler(const SizeOptions& opt)
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: IntMinimizeScript(opt),
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m(*this,opt.size(),0,
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(opt.size() < 31) ? (1 << (opt.size()-1))-1 : Int::Limits::max) {
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// Assume first mark to be zero
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rel(*this, m[0], IRT_EQ, 0);
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// Order marks
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rel(*this, m, IRT_LE);
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// Number of marks and differences
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const int n = m.size();
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const int n_d = (n*n-n)/2;
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// Array of differences
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IntVarArgs d(n_d);
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// Setup difference constraints
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for (int k=0, i=0; i<n-1; i++)
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for (int j=i+1; j<n; j++, k++)
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// d[k] is m[j]-m[i] and must be at least sum of first j-i integers
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rel(*this, d[k] = expr(*this, m[j]-m[i]),
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IRT_GQ, (j-i)*(j-i+1)/2);
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distinct(*this, d, opt.ipl());
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// Symmetry breaking
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if (n > 2)
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rel(*this, d[0], IRT_LE, d[n_d-1]);
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branch(*this, m, INT_VAR_NONE(), INT_VAL_MIN());
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}
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/// Return cost
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virtual IntVar cost(void) const {
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return m[m.size()-1];
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}
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/// Print solution
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virtual void
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print(std::ostream& os) const {
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os << "\tm[" << m.size() << "] = " << m << std::endl;
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}
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/// Constructor for cloning \a s
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GolombRuler(GolombRuler& s)
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: IntMinimizeScript(s) {
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m.update(*this, s.m);
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}
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/// Copy during cloning
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virtual Space*
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copy(void) {
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return new GolombRuler(*this);
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}
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};
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/** \brief Main-function
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* \relates GolombRuler
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*/
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int
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main(int argc, char* argv[]) {
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SizeOptions opt("GolombRuler");
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opt.solutions(0);
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opt.size(10);
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opt.ipl(IPL_BND);
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opt.parse(argc,argv);
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if (opt.size() > 0)
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IntMinimizeScript::run<GolombRuler,BAB,SizeOptions>(opt);
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return 0;
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}
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// STATISTICS: example-any
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