DisjointSets.hh

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// (c) Copyright Rosetta Commons Member Institutions.
// (c) This file is part of the Rosetta software suite and is made available under license.
// (c) The Rosetta software is developed by the contributing members of the Rosetta Commons.
// (c) For more information, see http://www.rosettacommons.org. Questions about this can be
// (c) addressed to University of Washington UW TechTransfer, email: license@u.washington.edu.

/// @file   core/graph/Graph.hh
/// @brief  generic graph class header
/// @author Andrew Leaver-Fay (aleaverfay@gmail.com)

#ifndef INCLUDED_core_graph_DisjointSets_hh
#define INCLUDED_core_graph_DisjointSets_hh

// Project Headers
// AUTO-REMOVED #include <platform/types.hh>

// Utility Headers
// AUTO-REMOVED #include <utility/vector1.hh>

// C++ headers
#include <map>

#include <utility/vector1_bool.hh>


namespace core {
namespace graph {

struct DS_Node {
  platform::Size index;
  platform::Size parent;
  platform::Size rank;
};

class DisjointSets
{

public:

  DisjointSets();

  ///  @brief ctor for class if the number of nodes is known upfront. Fastest.
  DisjointSets( platform::Size n_nodes );

  platform::Size n_nodes() const;

  /// @brief add a new node -- as implemented, O(N) operation
  /// use the DS(platform::Size) constructor for better speed.
  void ds_make_set();

  /// @brief return the representative for a node
  platform::Size ds_find( platform::Size node_id ) const;

  /// @brief make it so that two nodes end up in the same set
  void ds_union( platform::Size node1, platform::Size node2 );

  /// @brief DS_Node read access
  DS_Node const &
  node( platform::Size node_id ) const {
    return nodes_[ node_id ];
  }

  /// @brief count the number of disjoint sets. O(N)
  platform::Size n_disjoint_sets() const;

  /// @brief count the size of each disjoint set. O(N)
  utility::vector1< platform::Size >
  disjoint_set_sizes() const;

  /// @brief return the nodes in the set containing the specified node.
  utility::vector1< platform::Size >
  nodes_in_set( platform::Size node_id ) const;

  /// @brief return a map from the representative node of each set to
  ///  the list of nodes in their sets
  std::map< platform::Size, utility::vector1< platform::Size > >
  sets() const;

private:

  mutable utility::vector1< DS_Node > nodes_;

};



}
}

#endif