alpar@906: /* -*- C++ -*-
alpar@906:  *
alpar@1956:  * This file is a part of LEMON, a generic C++ optimization library
alpar@1956:  *
alpar@2553:  * Copyright (C) 2003-2008
alpar@1956:  * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
alpar@1359:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
alpar@906:  *
alpar@906:  * Permission to use, modify and distribute this software is granted
alpar@906:  * provided that this copyright notice appears in all copies. For
alpar@906:  * precise terms see the accompanying LICENSE file.
alpar@906:  *
alpar@906:  * This software is provided "AS IS" with no warranty of any kind,
alpar@906:  * express or implied, and with no claim as to its suitability for any
alpar@906:  * purpose.
alpar@906:  *
alpar@906:  */
alpar@906: 
alpar@921: #ifndef LEMON_KRUSKAL_H
alpar@921: #define LEMON_KRUSKAL_H
alpar@810: 
alpar@810: #include <algorithm>
klao@1942: #include <vector>
alpar@921: #include <lemon/unionfind.h>
deba@2424: #include <lemon/graph_utils.h>
deba@2424: #include <lemon/maps.h>
deba@2424: 
deba@2424: #include <lemon/radix_sort.h>
deba@2424: 
deba@1993: #include <lemon/bits/utility.h>
deba@1993: #include <lemon/bits/traits.h>
alpar@810: 
alpar@810: ///\ingroup spantree
alpar@810: ///\file
alpar@810: ///\brief Kruskal's algorithm to compute a minimum cost tree
alpar@810: ///
alpar@810: ///Kruskal's algorithm to compute a minimum cost tree.
alpar@1557: ///
alpar@810: 
alpar@921: namespace lemon {
alpar@810: 
deba@2424:   namespace _kruskal_bits {
alpar@810: 
deba@2424:     template <typename Map, typename Comp>
deba@2424:     struct MappedComp {
alpar@810: 
deba@2424:       typedef typename Map::Key Key;
deba@2424: 
deba@2424:       const Map& map;
deba@2424:       Comp comp;
deba@2424: 
deba@2424:       MappedComp(const Map& _map) 
deba@2424:         : map(_map), comp() {}
deba@2424: 
deba@2424:       bool operator()(const Key& left, const Key& right) {
deba@2424:         return comp(map[left], map[right]);
deba@2424:       }
deba@2424: 
deba@2424:     };
deba@2424:   
deba@2424:   }
deba@2424: 
deba@2424:   /// \brief Default traits class of Kruskal class.
deba@2424:   ///
deba@2424:   /// Default traits class of Kruskal class.
deba@2424:   /// \param _UGraph Undirected graph type.
deba@2424:   /// \param _CostMap Type of cost map.
deba@2424:   template <typename _UGraph, typename _CostMap>
deba@2424:   struct KruskalDefaultTraits{
deba@2424: 
deba@2424:     /// \brief The graph type the algorithm runs on. 
deba@2424:     typedef _UGraph UGraph;
deba@2424: 
deba@2424:     /// \brief The type of the map that stores the edge costs.
deba@2424:     ///
deba@2424:     /// The type of the map that stores the edge costs.
deba@2424:     /// It must meet the \ref concepts::ReadMap "ReadMap" concept.
deba@2424:     typedef _CostMap CostMap;
deba@2424: 
deba@2424:     /// \brief The type of the cost of the edges.
deba@2424:     typedef typename _CostMap::Value Value;
deba@2424: 
deba@2424:     /// \brief The type of the map that stores whether an edge is in the
deba@2424:     /// spanning tree or not.
deba@2424:     ///
deba@2424:     /// The type of the map that stores whether an edge is in the
deba@2424:     /// spanning tree or not.
deba@2424:     typedef typename _UGraph::template UEdgeMap<bool> TreeMap;
deba@2424: 
deba@2424:     /// \brief Instantiates a TreeMap.
deba@2424:     ///
deba@2424:     /// This function instantiates a \ref TreeMap.
deba@2424:     ///
deba@2424:     /// The first parameter is the graph, to which
deba@2424:     /// we would like to define the \ref TreeMap
deba@2424:     static TreeMap *createTreeMap(const _UGraph& graph){
deba@2424:       return new TreeMap(graph);
deba@2424:     }
deba@2424: 
deba@2424:     template <typename Iterator>
deba@2424:     static void sort(Iterator begin, Iterator end, const CostMap& cost) {
deba@2424:       _kruskal_bits::MappedComp<CostMap, std::less<Value> > comp(cost);
deba@2424:       std::sort(begin, end, comp);
deba@2424:     }
deba@2424: 
deba@2424:   };
deba@2424: 
deba@2428:   ///\ingroup spantree
deba@2428:   ///
deba@2424:   /// \brief Kruskal's algorithm to find a minimum cost tree of a graph.
deba@2424:   ///
deba@2424:   /// This class implements Kruskal's algorithm to find a minimum cost
deba@2424:   /// spanning tree. The 
deba@2424:   ///
deba@2424:   /// \param _UGraph Undirected graph type.
deba@2424:   /// \param _CostMap Type of cost map.
deba@2424:   template <typename _UGraph, typename _CostMap,
deba@2424:             typename _Traits = KruskalDefaultTraits<_UGraph, _CostMap> >
deba@2424:   class Kruskal {
deba@2424:   public:
deba@2424: 
deba@2424:     typedef _Traits Traits;
deba@2424: 
deba@2424:     typedef typename _Traits::UGraph UGraph;
deba@2424:     typedef typename _Traits::CostMap CostMap;
deba@2424: 
deba@2424:     typedef typename _Traits::TreeMap TreeMap;
deba@2424: 
deba@2424:     typedef typename _Traits::Value Value;
deba@2424: 
deba@2424:     template <typename Comp>
deba@2424:     struct DefSortCompareTraits : public Traits {
deba@2424:       template <typename Iterator>
deba@2424:       static void sort(Iterator begin, Iterator end, const CostMap& cost) {
deba@2424:         _kruskal_bits::MappedComp<CostMap, Comp> comp(cost, Comp());
deba@2424:         std::sort(begin, end, comp);
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:     /// \brief \ref named-templ-param "Named parameter" for setting the
deba@2424:     /// comparator object of the standard sort
deba@2424:     ///
deba@2424:     /// \ref named-templ-param "Named parameter" for setting the
deba@2424:     /// comparator object of the standard sort
deba@2424:     template <typename Comp>
deba@2424:     struct DefSortCompare
deba@2424:       : public Kruskal<UGraph, CostMap, DefSortCompareTraits<Comp> > {
deba@2424:       typedef Kruskal<UGraph, CostMap, DefSortCompareTraits<Comp> > Create;
deba@2424:     };    
deba@2424: 
deba@2424:     struct DefRadixSortTraits : public Traits {
deba@2424:       template <typename Iterator>
deba@2424:       static void sort(Iterator begin, Iterator end, const CostMap& cost) {
deba@2424:         radixSort(begin, end, cost);
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:     /// \brief \ref named-templ-param "Named parameter" for setting the
deba@2424:     /// sort function to radix sort
deba@2424:     ///
deba@2424:     /// \brief \ref named-templ-param "Named parameter" for setting the
deba@2424:     /// sort function to radix sort. The value type of the cost map should
deba@2424:     /// be integral, of course. 
deba@2424:     struct DefRadixSort
deba@2424:       : public Kruskal<UGraph, CostMap, DefRadixSortTraits> {
deba@2424:       typedef Kruskal<UGraph, CostMap, DefRadixSortTraits> Create;
deba@2424:     };    
deba@2424: 
deba@2424:     template <class TM>
deba@2424:     struct DefTreeMapTraits : public Traits {
deba@2424:       typedef TM TreeMap;
deba@2424:       static TreeMap *createTreeMap(const UGraph &) {
deba@2424:         throw UninitializedParameter();
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:     /// \brief \ref named-templ-param "Named parameter" for setting
deba@2424:     /// TreeMap
deba@2424:     ///
deba@2424:     /// \ref named-templ-param "Named parameter" for setting TreeMap
deba@2424:     ///
deba@2424:     template <class TM>
deba@2424:     struct DefTreeMap
deba@2424:       : public Kruskal< UGraph, CostMap, DefTreeMapTraits<TM> > {
deba@2424:       typedef Kruskal< UGraph, CostMap, DefTreeMapTraits<TM> > Create;
deba@2424:     };    
deba@2424:     
deba@2424: 
deba@2424:   private:
deba@2424: 
deba@2424:     typedef typename UGraph::Node Node;
deba@2424:     typedef typename UGraph::NodeIt NodeIt;
deba@2424: 
deba@2424:     typedef typename UGraph::UEdge UEdge;
deba@2424:     typedef typename UGraph::UEdgeIt UEdgeIt;
deba@2424: 
deba@2424:     const UGraph& graph;
deba@2424:     const CostMap& cost;
deba@2424:     
deba@2424:     std::vector<UEdge> edges;
deba@2424:     
deba@2424:     typedef typename UGraph::template NodeMap<int> UfIndex;
deba@2424:     typedef UnionFind<UfIndex> Uf;
deba@2424:     UfIndex *ufi;
deba@2424:     Uf *uf;
deba@2424: 
deba@2424:     int index;
deba@2424: 
deba@2424:     void initStructures() {
deba@2424:       if (!_tree) {
deba@2424:         _tree = Traits::createTreeMap(graph);
deba@2424:         local_tree = true;
deba@2424:       }
deba@2424:       if (!uf) {
deba@2424:         ufi = new typename UGraph::template NodeMap<int>(graph);
deba@2424:         uf = new UnionFind<typename UGraph::template NodeMap<int> >(*ufi);
deba@2424:       }
deba@2424:     }
deba@2424:     
deba@2424:     void initUnionFind() {
deba@2424:       uf->clear();
deba@2424:       for (NodeIt it(graph); it != INVALID; ++it) {
deba@2424:         uf->insert(it);
deba@2424:       }
deba@2424:     }
deba@2424: 
deba@2424:     bool local_tree;
deba@2424:     TreeMap* _tree;
deba@2424: 
deba@2424:   public:
deba@2424: 
deba@2424:     /// \brief Constructor
deba@2424:     ///
deba@2424:     /// Constructor of the algorithm.
deba@2424:     Kruskal(const UGraph& _graph, const CostMap& _cost) 
deba@2424:       : graph(_graph), cost(_cost),
deba@2424:         ufi(0), uf(0), local_tree(false), _tree(0) {}
deba@2424: 
deba@2424:     /// \brief Destructor
deba@2424:     ///
deba@2424:     /// Destructor
deba@2424:     ~Kruskal() {
deba@2424:       if (local_tree) {
deba@2424:         delete _tree;
deba@2424:       }
deba@2424:       if (uf) {
deba@2424:         delete uf;
deba@2424:         delete ufi;
deba@2424:       }
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Sets the map storing the tree edges.
deba@2424:     ///
deba@2424:     /// Sets the map storing the tree edges.
deba@2424:     /// If you don't use this function before calling \ref run(),
deba@2424:     /// it will allocate one. The destuctor deallocates this
deba@2424:     /// automatically allocated map, of course.
deba@2424:     /// \return \c *this </tt>
deba@2424:     Kruskal& treeMap(TreeMap &m){
deba@2424:       if (local_tree) {
deba@2424: 	delete _tree;
deba@2424: 	local_tree = false;
deba@2424:       }
deba@2424:       _tree = &m;
deba@2424:       return *this;
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Initialize the algorithm
deba@2424:     ///
deba@2424:     /// This member function initializes the unionfind data structure
deba@2424:     /// and sorts the edges into ascending order
deba@2424:     void init() {
deba@2424:       initStructures();
deba@2424:       initUnionFind();
deba@2424:       for (UEdgeIt e(graph); e != INVALID; ++e) {
deba@2424:         edges.push_back(e);
deba@2424:         _tree->set(e, false);
deba@2424:       }      
deba@2424:       Traits::sort(edges.begin(), edges.end(), cost); 
deba@2424:       index = 0;
deba@2424:     }
deba@2424: 
deba@2424: 
deba@2424:     /// \brief Initialize the algorithm
deba@2424:     ///
deba@2424:     /// This member function initializes the unionfind data structure
deba@2424:     /// and sets the edge order to the given sequence. The given
deba@2424:     /// sequence should be a valid STL range of undirected edges.
deba@2424:     template <typename Iterator>
deba@2424:     void initPresorted(Iterator begin, Iterator end) {
deba@2424:       initStructures();
deba@2424:       initUnionFind();
deba@2424:       edges.clear();
deba@2424:       std::copy(begin, end, std::back_inserter(edges));
deba@2424:       index = 0;
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Initialize the algorithm
deba@2424:     ///
deba@2424:     /// This member function initializes the unionfind data structure
deba@2428:     /// and sets the tree to empty. It does not change the order of
deba@2428:     /// the edges, it uses the order of the previous running.
deba@2424:     void reinit() {
deba@2424:       initStructures();
deba@2424:       initUnionFind();
deba@2424:       for (UEdgeIt e(graph); e != INVALID; ++e) {
deba@2424:         _tree->set(e, false);
deba@2424:       }
deba@2424:       index = 0;
deba@2424:     }
deba@2424: 
deba@2424: 
deba@2424:     /// \brief Executes the algorithm.
deba@2424:     ///
deba@2424:     /// Executes the algorithm.
deba@2424:     ///
deba@2424:     /// \pre init() must be called before using this function.
deba@2424:     ///
deba@2424:     /// This method runs the %Kruskal algorithm.
deba@2424:     void start() {
deba@2424:       while (index < int(edges.size())) {
deba@2424:         if (uf->join(graph.target(edges[index]), graph.source(edges[index]))) {
deba@2424:           _tree->set(edges[index], true);
deba@2424:         }
deba@2424:         ++index;
deba@2424:       }
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Runs the prim algorithm until it find a new tree edge
deba@2424:     ///
deba@2424:     /// Runs the prim algorithm until it find a new tree edge. If it
deba@2424:     /// does not next tree edge in the sequence it gives back \c INVALID.
deba@2424:     UEdge findNextTreeEdge() {
deba@2424:       while (index < int(edges.size())) {
deba@2424:         if (uf->join(graph.target(edges[index]), graph.source(edges[index]))) {
deba@2424:           _tree->set(edges[index], true);
deba@2424:           return edges[index++];
deba@2424:         }        
deba@2424:         ++index;
deba@2424:       }
deba@2424:       return INVALID;
deba@2424:     }
deba@2424:       
deba@2424:     /// \brief Processes the next edge in the sequence
deba@2424:     ///
deba@2424:     /// Processes the next edge in the sequence.
deba@2424:     ///
deba@2424:     /// \return The prcocessed edge.
deba@2424:     ///
deba@2424:     /// \warning The sequence must not be empty!
deba@2424:     UEdge processNextEdge() {
deba@2424:       UEdge edge = edges[index++];
deba@2424:       processEdge(edge);
deba@2424:       return edge;
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Processes an arbitrary edge
deba@2424:     ///
deba@2424:     /// Processes the next edge in the sequence.
deba@2424:     ///
deba@2424:     /// \return True when the edge is a tree edge.
deba@2424:     bool processEdge(const UEdge& edge) {
deba@2424:       if (uf->join(graph.target(edge), graph.source(edge))) {
deba@2424:         _tree->set(edge, true);
deba@2424:         return true;
deba@2424:       } else {
deba@2424:         return false;
deba@2424:       }    
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Returns \c false if there are edge to be processed in
deba@2424:     /// sequence
deba@2424:     ///
deba@2424:     /// Returns \c false if there are nodes to be processed in the
deba@2424:     /// sequence
deba@2424:     bool emptyQueue() {
deba@2424:       return index == int(edges.size());
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Returns the next edge to be processed
deba@2424:     ///
deba@2424:     /// Returns the next edge to be processed
deba@2424:     ///
deba@2424:     UEdge nextEdge() const {
deba@2424:       return edges[index];
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Runs %Kruskal algorithm.
deba@2424:     ///
deba@2424:     /// This method runs the %Kruskal algorithm in order to compute the
deba@2424:     /// minimum spanning tree (or minimum spanning forest).  The
deba@2424:     /// method also works on graphs that has more than one components.
deba@2424:     /// In this case it computes the minimum spanning forest.
deba@2424:     void run() {
deba@2424:       init();
deba@2424:       start();
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Returns a reference to the tree edges map
deba@2424:     ///
deba@2424:     /// Returns a reference to the TreeEdgeMap of the edges of the
deba@2424:     /// minimum spanning tree. The value of the map is \c true only if
deba@2424:     /// the edge is in the minimum spanning tree.
deba@2424:     ///
deba@2424:     const TreeMap &treeMap() const { return *_tree;}
deba@2424: 
deba@2424:     /// \brief Returns the total cost of the tree
deba@2424:     ///
deba@2424:     /// Returns the total cost of the tree
deba@2424:     Value treeValue() const {
deba@2424:       Value value = 0;
deba@2424:       for (UEdgeIt it(graph); it != INVALID; ++it) {
deba@2424:         if ((*_tree)[it]) {
deba@2424:           value += cost[it];
deba@2424:         }
deba@2424:       }
deba@2424:       return value;
deba@2424:     }
deba@2424: 
deba@2424:     /// \brief Returns true when the given edge is tree edge
deba@2424:     ///
deba@2424:     /// Returns true when the given edge is tree edge
deba@2424:     bool tree(UEdge e) const {
deba@2424:       return (*_tree)[e];
deba@2424:     }
deba@2424:     
deba@2424:     
deba@2424:   };
deba@2424: 
deba@2424: 
deba@2424:   namespace _kruskal_bits {
deba@2424: 
deba@2424:     template <typename Graph, typename In, typename Out>
deba@2424:     typename In::value_type::second_type
deba@2424:     kruskal(const Graph& graph, const In& in, Out& out) {
deba@2424:       typedef typename In::value_type::second_type Value;
deba@2424:       typedef typename Graph::template NodeMap<int> IndexMap;
deba@2424:       typedef typename Graph::Node Node;
deba@2424:       
deba@2424:       IndexMap index(graph);
deba@2424:       UnionFind<IndexMap> uf(index);
deba@2424:       for (typename Graph::NodeIt it(graph); it != INVALID; ++it) {
deba@2424:         uf.insert(it);
deba@2424:       }
deba@2424:       
deba@2424:       Value tree_value = 0;
deba@2424:       for (typename In::const_iterator it = in.begin(); it != in.end(); ++it) {
deba@2424:         if (uf.join(graph.target(it->first),graph.source(it->first))) {
deba@2424:           out.set(it->first, true);
deba@2424:           tree_value += it->second;
deba@2424:         }
deba@2424:         else {
deba@2424:           out.set(it->first, false);
deba@2424:         }
deba@2424:       }
deba@2424:       return tree_value;
deba@2424:     }
deba@2424: 
deba@2424: 
deba@2424:     template <typename Sequence>
deba@2424:     struct PairComp {
deba@2424:       typedef typename Sequence::value_type Value;
deba@2424:       bool operator()(const Value& left, const Value& right) {
deba@2424: 	return left.second < right.second;
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In, typename Enable = void>
deba@2424:     struct SequenceInputIndicator {
deba@2424:       static const bool value = false;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In>
deba@2424:     struct SequenceInputIndicator<In, 
deba@2424:       typename exists<typename In::value_type::first_type>::type> {
deba@2424:       static const bool value = true;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In, typename Enable = void>
deba@2424:     struct MapInputIndicator {
deba@2424:       static const bool value = false;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In>
deba@2424:     struct MapInputIndicator<In, 
deba@2424:       typename exists<typename In::Value>::type> {
deba@2424:       static const bool value = true;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In, typename Enable = void>
deba@2424:     struct SequenceOutputIndicator {
deba@2424:       static const bool value = false;
deba@2424:     };
deba@2424:  
deba@2424:     template <typename Out>
deba@2424:     struct SequenceOutputIndicator<Out, 
deba@2424:       typename exists<typename Out::value_type>::type> {
deba@2424:       static const bool value = true;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename Out, typename Enable = void>
deba@2424:     struct MapOutputIndicator {
deba@2424:       static const bool value = false;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename Out>
deba@2424:     struct MapOutputIndicator<Out, 
deba@2424:       typename exists<typename Out::Value>::type> {
deba@2424:       static const bool value = true;
deba@2424:     };
deba@2424: 
deba@2424:     template <typename In, typename InEnable = void>
deba@2424:     struct KruskalValueSelector {};
deba@2424: 
deba@2424:     template <typename In>
deba@2424:     struct KruskalValueSelector<In,
deba@2424:       typename enable_if<SequenceInputIndicator<In>, void>::type> 
deba@2424:     {
deba@2424:       typedef typename In::value_type::second_type Value;
deba@2424:     };    
deba@2424: 
deba@2424:     template <typename In>
deba@2424:     struct KruskalValueSelector<In,
deba@2424:       typename enable_if<MapInputIndicator<In>, void>::type> 
deba@2424:     {
deba@2424:       typedef typename In::Value Value;
deba@2424:     };    
deba@2424:     
deba@2424:     template <typename Graph, typename In, typename Out,
deba@2424:               typename InEnable = void>
deba@2424:     struct KruskalInputSelector {};
deba@2424: 
deba@2424:     template <typename Graph, typename In, typename Out,
deba@2424:               typename InEnable = void>
deba@2424:     struct KruskalOutputSelector {};
deba@2424:     
deba@2424:     template <typename Graph, typename In, typename Out>
deba@2424:     struct KruskalInputSelector<Graph, In, Out,
deba@2424:       typename enable_if<SequenceInputIndicator<In>, void>::type > 
deba@2424:     {
deba@2424:       typedef typename In::value_type::second_type Value;
deba@2424: 
deba@2424:       static Value kruskal(const Graph& graph, const In& in, Out& out) {
deba@2424:         return KruskalOutputSelector<Graph, In, Out>::
deba@2424:           kruskal(graph, in, out);
deba@2424:       }
deba@2424: 
deba@2424:     };
deba@2424: 
deba@2424:     template <typename Graph, typename In, typename Out>
deba@2424:     struct KruskalInputSelector<Graph, In, Out,
deba@2424:       typename enable_if<MapInputIndicator<In>, void>::type > 
deba@2424:     {
deba@2424:       typedef typename In::Value Value;
deba@2424:       static Value kruskal(const Graph& graph, const In& in, Out& out) {
deba@2424:         typedef typename In::Key MapEdge;
deba@2424:         typedef typename In::Value Value;
deba@2424:         typedef typename ItemSetTraits<Graph, MapEdge>::ItemIt MapEdgeIt;
deba@2424:         typedef std::vector<std::pair<MapEdge, Value> > Sequence;
deba@2424:         Sequence seq;
deba@2424:         
deba@2424:         for (MapEdgeIt it(graph); it != INVALID; ++it) {
ladanyi@2431:           seq.push_back(std::make_pair(it, in[it]));
deba@2424:         }
deba@2424: 
deba@2424:         std::sort(seq.begin(), seq.end(), PairComp<Sequence>());
deba@2424:         return KruskalOutputSelector<Graph, Sequence, Out>::
deba@2424:           kruskal(graph, seq, out);
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:     template <typename Graph, typename In, typename Out>
deba@2424:     struct KruskalOutputSelector<Graph, In, Out,
deba@2424:       typename enable_if<SequenceOutputIndicator<Out>, void>::type > 
deba@2424:     {
deba@2424:       typedef typename In::value_type::second_type Value;
deba@2424: 
deba@2424:       static Value kruskal(const Graph& graph, const In& in, Out& out) {
deba@2424:         typedef StoreBoolMap<Out> Map;
deba@2424:         Map map(out);
deba@2424:         return _kruskal_bits::kruskal(graph, in, map);
deba@2424:       }
deba@2424: 
deba@2424:     };
deba@2424: 
deba@2424:     template <typename Graph, typename In, typename Out>
deba@2424:     struct KruskalOutputSelector<Graph, In, Out,
deba@2424:       typename enable_if<MapOutputIndicator<Out>, void>::type > 
deba@2424:     {
deba@2424:       typedef typename In::value_type::second_type Value;
deba@2424: 
deba@2424:       static Value kruskal(const Graph& graph, const In& in, Out& out) {
deba@2424:         return _kruskal_bits::kruskal(graph, in, out);
deba@2424:       }
deba@2424:     };
deba@2424: 
deba@2424:   }
deba@2424: 
deba@2424:   /// \ingroup spantree
deba@2424:   ///
deba@2424:   /// \brief Kruskal's algorithm to find a minimum cost tree of a graph.
deba@2424:   ///
alpar@810:   /// This function runs Kruskal's algorithm to find a minimum cost tree.
alpar@1557:   /// Due to hard C++ hacking, it accepts various input and output types.
alpar@1557:   ///
alpar@1555:   /// \param g The graph the algorithm runs on.
alpar@2260:   /// It can be either \ref concepts::Graph "directed" or 
alpar@2260:   /// \ref concepts::UGraph "undirected".
alpar@1555:   /// If the graph is directed, the algorithm consider it to be 
alpar@1555:   /// undirected by disregarding the direction of the edges.
alpar@810:   ///
alpar@1557:   /// \param in This object is used to describe the edge costs. It can be one
alpar@1557:   /// of the following choices.
deba@2424:   /// - An STL compatible 'Forward Container' with
deba@2424:   /// <tt>std::pair<GR::UEdge,X></tt> or
deba@2424:   /// <tt>std::pair<GR::Edge,X></tt> as its <tt>value_type</tt>, where
deba@2424:   /// \c X is the type of the costs. The pairs indicates the edges
deba@2424:   /// along with the assigned cost. <em>They must be in a
alpar@1557:   /// cost-ascending order.</em>
alpar@1557:   /// - Any readable Edge map. The values of the map indicate the edge costs.
alpar@810:   ///
alpar@1557:   /// \retval out Here we also have a choise.
deba@2424:   /// - It can be a writable \c bool edge map.  After running the
deba@2424:   /// algorithm this will contain the found minimum cost spanning
deba@2424:   /// tree: the value of an edge will be set to \c true if it belongs
deba@2424:   /// to the tree, otherwise it will be set to \c false. The value of
deba@2424:   /// each edge will be set exactly once.
alpar@1557:   /// - It can also be an iteraror of an STL Container with
deba@2424:   /// <tt>GR::UEdge</tt> or <tt>GR::Edge</tt> as its
deba@2424:   /// <tt>value_type</tt>.  The algorithm copies the elements of the
deba@2424:   /// found tree into this sequence.  For example, if we know that the
deba@2424:   /// spanning tree of the graph \c g has say 53 edges, then we can
deba@2424:   /// put its edges into an STL vector \c tree with a code like this.
alpar@1946:   ///\code
alpar@1557:   /// std::vector<Edge> tree(53);
alpar@1557:   /// kruskal(g,cost,tree.begin());
alpar@1946:   ///\endcode
deba@2424:   /// Or if we don't know in advance the size of the tree, we can
deba@2424:   /// write this.  
deba@2424:   ///\code std::vector<Edge> tree;
deba@2424:   /// kruskal(g,cost,std::back_inserter(tree)); 
alpar@1946:   ///\endcode
alpar@810:   ///
deba@2424:   /// \return The total cost of the found tree.
alpar@1449:   ///
deba@2424:   /// \warning If kruskal runs on an be consistent of using the same
deba@2424:   /// Edge type for input and output.
alpar@1603:   ///
alpar@810: 
alpar@1557: #ifdef DOXYGEN
deba@2424:   template <class Graph, class In, class Out>
deba@2424:   Value kruskal(GR const& g, const In& in, Out& out)
deba@2424: #else 
deba@2424:   template <class Graph, class In, class Out>
deba@2424:   inline typename _kruskal_bits::KruskalValueSelector<In>::Value 
deba@2424:   kruskal(const Graph& graph, const In& in, Out& out) 
alpar@1557: #endif
alpar@810:   {
deba@2424:     return _kruskal_bits::KruskalInputSelector<Graph, In, Out>::
deba@2424:       kruskal(graph, in, out);
alpar@810:   }
alpar@810: 
alpar@1557:  
alpar@810:   
klao@885: 
deba@2424:   template <class Graph, class In, class Out>
deba@2424:   inline typename _kruskal_bits::KruskalValueSelector<In>::Value
deba@2424:   kruskal(const Graph& graph, const In& in, const Out& out)
alpar@1557:   {
deba@2424:     return _kruskal_bits::KruskalInputSelector<Graph, In, const Out>::
deba@2424:       kruskal(graph, in, out);
deba@2424:   }  
alpar@810: 
alpar@921: } //namespace lemon
alpar@810: 
alpar@921: #endif //LEMON_KRUSKAL_H