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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
* Main authors:
* Christian Schulte <schulte@gecode.org>
*
* Copyright:
* Christian Schulte, 2001
*
* 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 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
*/
int
main(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
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