opBinTree.H

/*
  This file is part of Aleph system

  Copyright (c) 2002, 2003, 2004, 2005, 2006
  UNIVERSITY LOS ANDES (ULA) Merida - REPÚBLICA BOLIVARIANA DE VENEZUELA  

  - Center of Studies in Microelectronics & Distributed Systems (CEMISID) 
  - ULA Computer Science Department
  - FUNDACITE Mérida - Ministerio de Ciencia y Tecnología

  PERMISSION TO USE, COPY, MODIFY AND DISTRIBUTE THIS SOFTWARE AND ITS
  DOCUMENTATION IS HEREBY GRANTED, PROVIDED THAT BOTH THE COPYRIGHT
  NOTICE AND THIS PERMISSION NOTICE APPEAR IN ALL COPIES OF THE
  SOFTWARE, DERIVATIVE WORKS OR MODIFIED VERSIONS, AND ANY PORTIONS
  THEREOF, AND THAT BOTH NOTICES APPEAR IN SUPPORTING DOCUMENTATION.

  Aleph is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  or FITNESS FOR A PARTICULAR PURPOSE.

  UNIVERSIDAD DE LOS ANDES requests users of this software to return to 

  Leandro Leon
  CEMISID 
  Ed La Hechicera 
  3er piso, ala sur
  Facultad de Ingenieria 
  Universidad de Los Andes 
  Merida - REPÚBLICA BOLIVARIANA DE VENEZUELA    or

  lrleon@ula.ve

  any improvements or extensions that they make and grant Universidad 
  de Los Andes (ULA) the rights to redistribute these changes. 

  Aleph is (or was) granted by: 
  - Consejo de Desarrollo Cientifico, Humanistico, Tecnico de la ULA 
    (CDCHT)
  - Fundacite Mérida
*/


# ifndef OPBINTREE_H 
# define OPBINTREE_H

# include <tpl_dynArray.H>

namespace Aleph {

# define COST(i,j) (cost[(i)*(n+1) + (j)])
# define TREE(i,j) (tree[(i)*(n+1) + (j)])

static inline double sum_p(double p[], const int & i, const int & j);

    static inline int 
min_index(DynArray <double>&, const int &, const int &, const int &);

    static inline 
void compute_optimal_costs(DynArray <double> & cost, 
                           double              p[], 
                           const int &         n, 
                           DynArray <int>    & tree)
{
  int i, j, k;
  for (i = 1; i <= n; ++i)
    {
      COST(i, i - 1) = 0;
      TREE(i, i) = i;
    }
  for (i = 0; i < n; ++i)
    for (j = 1; j <= n - i; ++j)
      {
        k          = j + i;
        TREE(j, k) = min_index(cost, j, k, n);
        COST(j, k) = sum_p(p, j, k) + 
                     COST(j, TREE(j, k) - 1) + COST(TREE(j, k) + 1, k);
      }
}
static inline double sum_p(double p[], const int & i, const int & j)
{
  double sum = 0.0;

  for (int k = i - 1; k < j; ++k)
    sum += p[k];

  return sum;
}
static inline int min_index(DynArray <double>& cost, 
                            const int & j, const int & k, const int & n)
{
  int ret_val;
  double min_sum = 1e32;
  double sum;
  
  for (int i = j; i <= k; ++i)
    {
      sum = COST(j, i - 1) + COST(i + 1, k);

      if (sum < min_sum)
        {
          min_sum = sum;
          ret_val = i;
        }
    }

  return ret_val;
}
    template<class Node, typename Key> static inline
Node * compute_tree(Key keys[], DynArray<int>& tree, 
                    const int & n, const int & i, cons int & j)
{
  if (i > j)
    return Node::NullPtr;

  Node * root = new Node (keys[TREE(i, j) - 1]);

  LLINK(root) = compute_tree <Node, Key>(keys, tree, n, i, TREE(i, j) - 1);
  RLINK(root) = compute_tree <Node, Key>(keys, tree, n, TREE(i, j) + 1, j);

  return root;
}
    template <class Node, typename Key>
Node * build_optimal_tree(Key keys[], double p[], const int & n)
{
  DynArray <int> tree((n + 1)*(n + 1));
  DynArray <double> cost((n + 1)*(n + 1));
 
  compute_optimal_costs(cost, p, n, tree);

  return compute_tree<Node, Key> (keys, tree, n, 1, n);
}


# undef COST
# undef TREE
} // end namespace Aleph
# endif // OPBINTREE_H

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