main page modules namespaces classes files
Gecode home

search for 

warehouses.cc

Go to the documentation of this file.

/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2005
 *
 *  Last modified:
 *     $Date: 2006-08-04 16:06:52 +0200 (Fri, 04 Aug 2006) $ by $Author: schulte $
 *     $Revision: 3517 $
 *
 *  This file is part of Gecode, the generic constraint
 *  development environment:
 *     http://www.gecode.org
 *
 *  See the file "LICENSE" for information on usage and
 *  redistribution of this file, and for a
 *     DISCLAIMER OF ALL WARRANTIES.
 *
 */

#include "examples/support.hh"
#include "gecode/minimodel.hh"

static const int n_suppliers = 5;
static const int n_stores = 10;

static const int building_cost = 30;

static const int capacity[n_suppliers] = {
  1, 4, 2, 1, 3
};

static const int cost_matrix[n_stores][n_suppliers] = {
  {20, 24, 11, 25, 30},
  {28, 27, 82, 83, 74},
  {74, 97, 71, 96, 70},
  { 2, 55, 73, 69, 61},
  {46, 96, 59, 83,  4},
  {42, 22, 29, 67, 59},
  { 1,  5, 73, 59, 56},
  {10, 73, 13, 43, 96},
  {93, 35, 63, 85, 46},
  {47, 65, 55, 71, 95}
};



class Warehouses : public Example {
protected:
  IntVarArray supplier;
  BoolVarArray open;
  IntVarArray cost;
  IntVar total;
public:
  Warehouses(const Options& opt)
    : supplier(this, n_stores, 0, n_suppliers-1),
      open(this, n_suppliers, 0, 1),
      cost(this, n_stores, 0, Limits::Int::int_max),
      total(this, 0, Limits::Int::int_max) {
    // Compute total cost
    {
      IntArgs c(n_stores + n_suppliers);
      IntVarArgs x(n_stores + n_suppliers);
      for (int i=0; i<n_stores; i++) {
        c[i]=1; x[i]=cost[i];
      }
      for (int i=0; i<n_suppliers; i++) {
        c[n_stores+i]=building_cost;
        x[n_stores+i]=open[i];
      }
      linear(this, c, x, IRT_EQ, total);
    }

    // Compute cost for store
    for (int i=0; i<n_stores; i++) {
      IntArgs c(n_suppliers);
      for (int j=0; j<n_suppliers; j++)
        c[j] = cost_matrix[i][j];
      element(this, c, supplier[i], cost[i]);
    }

    // Do not exceed capacity
    for (int i=0; i<n_suppliers; i++)
      count(this, supplier, i, IRT_LQ, capacity[i]);

    // A warehouse is open, if it supplies to a shop
    for (int i=0; i<n_suppliers; i++) {
      BoolVarArgs store_by_supplier(n_stores);
      for (int j=0; j<n_stores; j++)
        store_by_supplier[j] = post(this, ~(supplier[j] == i));
      BoolVar b(this, 0, 1);
      rel(this, open[i], IRT_EQ, 1, b);
      linear(this, store_by_supplier, IRT_GR, 0, b);
    }

    branch(this, cost, BVAR_REGRET_MIN_MAX, BVAL_MIN);
  }

  void
  constrain(Space* s) {
    rel(this, total, IRT_LE, static_cast<Warehouses*>(s)->total.val());
  }
  Warehouses(bool share, Warehouses& s) : Example(share,s) {
    supplier.update(this, share, s.supplier);
    open.update(this, share, s.open);
    cost.update(this, share, s.cost);
    total.update(this, share, s.total);
  }

  virtual Space*
  copy(bool share) {
    return new Warehouses(share,*this);
  }
  virtual void
  print(void) {
    std::cout << "\tSupplier: {";
    for (int i=0; i<n_stores; i++) {
      std::cout << supplier[i] << ((i<n_stores-1)?", ":"};\n");
    }
    std::cout << "\tCost: {";
    for (int i=0; i<n_stores; i++) {
      std::cout << cost[i] << ((i<n_stores-1)?", ":"};\n");
    }
    std::cout << "\tTotal cost: " << total << std::endl;
    std::cout << std::endl;
  }
};

int
main(int argc, char** argv) {
  Options opt("Warehouses");
  opt.solutions  = 0;
  opt.iterations = 10;
  opt.naive      = true;
  opt.parse(argc,argv);
  Example::run<Warehouses,BAB>(opt);
  return 0;
}

// STATISTICS: example-any