partition.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, 2003
 *
 *  Last modified:
 *     $Date: 2011-06-20 22:39:54 +0200 (Mon, 20 Jun 2011) $ by $Author: schulte $
 *     $Revision: 12069 $
 *
 *  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
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 *  permit persons to whom the Software is furnished to do so, subject to
 *  the following conditions:
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 *  included in all copies or substantial portions of the Software.
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 */

#include <gecode/driver.hh>
#include <gecode/int.hh>
#include <gecode/minimodel.hh>

using namespace Gecode;

class Partition : public Script {
protected:
  IntVarArray x;
  IntVarArray y;
public:
  Partition(const SizeOptions& opt)
    : x(*this,opt.size(),1,2*opt.size()),
      y(*this,opt.size(),1,2*opt.size()) {
    const int n = opt.size();

    // Break symmetries by ordering numbers in each group
    rel(*this, x, IRT_LE);
    rel(*this, y, IRT_LE);

    rel(*this, x[0], IRT_LE, y[0]);

    IntVarArgs xy(2*n);
    for (int i = n; i--; ) {
      xy[i] = x[i]; xy[n+i] = y[i];
    }
    distinct(*this, xy, opt.icl());

    IntArgs c(2*n);
    for (int i = n; i--; ) {
      c[i] = 1; c[n+i] = -1;
    }
    linear(*this, c, xy, IRT_EQ, 0);

    // Array of products
    IntVarArgs sxy(2*n), sx(n), sy(n);

    for (int i = n; i--; ) {
      sx[i] = sxy[i] =   expr(*this, sqr(x[i]));
      sy[i] = sxy[n+i] = expr(*this, sqr(y[i]));
    }
    linear(*this, c, sxy, IRT_EQ, 0);

    // Redundant constraints
    linear(*this, x, IRT_EQ, 2*n*(2*n+1)/4);
    linear(*this, y, IRT_EQ, 2*n*(2*n+1)/4);
    linear(*this, sx, IRT_EQ, 2*n*(2*n+1)*(4*n+1)/12);
    linear(*this, sy, IRT_EQ, 2*n*(2*n+1)*(4*n+1)/12);
    branch(*this, xy, INT_VAR_SIZE_AFC_MIN, INT_VAL_MIN);
  }

  Partition(bool share, Partition& s) : Script(share,s) {
    x.update(*this, share, s.x);
    y.update(*this, share, s.y);
  }
  virtual Space*
  copy(bool share) {
    return new Partition(share,*this);
  }
  virtual void
  print(std::ostream& os) const {
    os << "\t";
    int a, b;
    a = b = 0;
    for (int i = 0; i < x.size(); i++) {
      a += x[i].val();
      b += x[i].val()*x[i].val();
      os << x[i] << ", ";
    }
    os << " = " << a << ", " << b << std::endl << "\t";
    a = b = 0;
    for (int i = 0; i < y.size(); i++) {
      a += y[i].val();
      b += y[i].val()*y[i].val();
      os << y[i] << ", ";
    }
    os << " = " << a << ", " << b << std::endl;
  }
};

int
main(int argc, char* argv[]) {
  SizeOptions opt("Partition");
  opt.size(32);
  opt.icl(ICL_BND);
  opt.parse(argc,argv);
  Script::run<Partition,DFS,SizeOptions>(opt);
  return 0;
}


// STATISTICS: example-any