warehouses.cc

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/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
/*
 *  Main authors:
 *     Christian Schulte <schulte@gecode.org>
 *
 *  Copyright:
 *     Christian Schulte, 2005
 *
 *  Last modified:
 *     $Date: 2008-02-06 18:48:22 +0100 (Wed, 06 Feb 2008) $ by $Author: schulte $
 *     $Revision: 6102 $
 *
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 *     http://www.gecode.org
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#include "examples/support.hh"
#include "gecode/minimodel.hh"

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

const int building_cost = 30;

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

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&)
    : supplier(this, n_stores, 0, n_suppliers-1),
      open(this, n_suppliers, 0, 1),
      cost(this, n_stores, 0, Int::Limits::max),
      total(this, 0, Int::Limits::max) {
    // Compute total cost
    {
      // Opening cost
      IntArgs c(n_suppliers);
      for (int i=0; i<n_suppliers; i++)
        c[i]=building_cost;
      IntVar oc(this, 0, Int::Limits::max);
      linear(this, c, open, IRT_EQ, oc);
      // Total cost of stores
      IntVarArgs tc(n_stores+1);
      for (int i=0; i<n_stores; i++)
        tc[i]=cost[i];
      tc[n_stores] = oc;
      linear(this, tc, 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));
      rel(this, BOT_OR, store_by_supplier, open[i]);
    }

    branch(this, cost, INT_VAR_REGRET_MIN_MAX, INT_VAL_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(std::ostream& os) {
    os << "\tSupplier: " << supplier << std::endl
       << "\tCost: " << cost << std::endl
       << "\tTotal cost: " << total << std::endl
       << std::endl;
  }
};

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

// STATISTICS: example-any