golomb-ruler.cpp

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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
 *
 *  Last modified:
 *     $Date: 2011-08-29 12:13:11 +0200 (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,
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 *  permit persons to whom the Software is furnished to do so, subject to
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#include <gecode/driver.hh>
#include <gecode/int.hh>
#include <gecode/minimodel.hh>

#include <iomanip>

using namespace Gecode;

class GolombRuler : public MinimizeScript {
protected:
  IntVarArray m;
public:
  enum {
    SEARCH_BAB,    
    SEARCH_RESTART 
  };
  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);
  }

  virtual IntVar cost(void) const {
    return m[m.size()-1];
  }

  virtual void
  print(std::ostream& os) const {
    os << "\tm[" << m.size() << "] = " << m << std::endl;
  }

  GolombRuler(bool share, GolombRuler& s)
    : MinimizeScript(share,s) {
    m.update(*this, share, s.m);
  }
  virtual Space*
  copy(bool share) {
    return new GolombRuler(share,*this);
  }
};

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