lemon/topology.h
changeset 1757 bd4199049036
parent 1740 4cade8579363
child 1763 49045f2d28d4
equal deleted inserted replaced
3:df1e3d8f0665 4:362b9e285d33
    18 #define LEMON_TOPOLOGY_H
    18 #define LEMON_TOPOLOGY_H
    19 
    19 
    20 #include <lemon/dfs.h>
    20 #include <lemon/dfs.h>
    21 #include <lemon/bfs.h>
    21 #include <lemon/bfs.h>
    22 #include <lemon/graph_utils.h>
    22 #include <lemon/graph_utils.h>
       
    23 #include <lemon/graph_adaptor.h>
       
    24 #include <lemon/maps.h>
    23 
    25 
    24 #include <lemon/concept/graph.h>
    26 #include <lemon/concept/graph.h>
    25 #include <lemon/concept/undir_graph.h>
    27 #include <lemon/concept/undir_graph.h>
    26 #include <lemon/concept_check.h>
    28 #include <lemon/concept_check.h>
    27 
    29 
    28 /// \ingroup flowalgs
    30 #include <lemon/bin_heap.h>
       
    31 #include <lemon/linear_heap.h>
       
    32 
       
    33 #include <stack>
       
    34 #include <functional>
       
    35 
       
    36 /// \ingroup topology
    29 /// \file
    37 /// \file
    30 /// \brief Topology related algorithms
    38 /// \brief Topology related algorithms
    31 ///
    39 ///
    32 /// Topology related algorithms
    40 /// Topology related algorithms
    33 ///\todo Place the file contents is the module tree.
       
    34 
    41 
    35 namespace lemon {
    42 namespace lemon {
    36 
    43 
       
    44   /// \ingroup topology
       
    45   ///
       
    46   /// \brief Check that the given undirected graph is connected.
       
    47   ///
       
    48   /// Check that the given undirected graph connected.
       
    49   /// \param graph The undirected graph.
       
    50   /// \return %True when there is path between any two nodes in the graph.
       
    51   /// \warning The empty graph is not connected.
       
    52   template <typename UndirGraph>
       
    53   bool connected(const UndirGraph& graph) {
       
    54     checkConcept<concept::UndirGraph, UndirGraph>();
       
    55     typedef typename UndirGraph::NodeIt NodeIt;
       
    56     if (NodeIt(graph) == INVALID) return false;
       
    57     Dfs<UndirGraph> dfs(graph);
       
    58     dfs.run(NodeIt(graph));
       
    59     for (NodeIt it(graph); it != INVALID; ++it) {
       
    60       if (!dfs.reached(it)) {
       
    61 	return false;
       
    62       }
       
    63     }
       
    64     return true;
       
    65   }
       
    66 
       
    67   /// \ingroup topology
       
    68   ///
       
    69   /// \brief Count the number of connected components of an undirected graph
       
    70   ///
       
    71   /// Count the number of connected components of an undirected graph
       
    72   ///
       
    73   /// \param g The graph. In must be undirected.
       
    74   /// \return The number of components
       
    75   template <typename UndirGraph>
       
    76   int countConnectedComponents(const UndirGraph &graph) {
       
    77     checkConcept<concept::UndirGraph, UndirGraph>();
       
    78     typedef typename UndirGraph::Node Node;
       
    79     typedef typename UndirGraph::Edge Edge;
       
    80 
       
    81     typedef NullMap<Node, Edge> PredMap;
       
    82     typedef NullMap<Node, int> DistMap;
       
    83 
       
    84     int compNum = 0;
       
    85     typename Bfs<UndirGraph>::
       
    86       template DefPredMap<PredMap>::
       
    87       template DefDistMap<DistMap>::
       
    88       Create bfs(graph);
       
    89 
       
    90     PredMap predMap;
       
    91     bfs.predMap(predMap);
       
    92 
       
    93     DistMap distMap;
       
    94     bfs.distMap(distMap);
       
    95 
       
    96     bfs.init();
       
    97     for(typename UndirGraph::NodeIt n(graph); n != INVALID; ++n) {
       
    98       if (!bfs.reached(n)) {
       
    99 	bfs.addSource(n);
       
   100 	bfs.start();
       
   101 	++compNum;
       
   102       }
       
   103     }
       
   104     return compNum;
       
   105   }
       
   106 
       
   107   /// \ingroup topology
       
   108   ///
       
   109   /// \brief Find the connected components of an undirected graph
       
   110   ///
       
   111   /// Find the connected components of an undirected graph.
       
   112   ///
       
   113   /// \param g The graph. In must be undirected.
       
   114   /// \retval comp A writable node map. The values will be set from 0 to
       
   115   /// the number of the connected components minus one. Each values of the map
       
   116   /// will be set exactly once, the values of a certain component will be
       
   117   /// set continuously.
       
   118   /// \return The number of components
       
   119   template <class UndirGraph, class NodeMap>
       
   120   int connectedComponents(const UndirGraph &graph, NodeMap &compMap) {
       
   121     checkConcept<concept::UndirGraph, UndirGraph>();
       
   122     typedef typename UndirGraph::Node Node;
       
   123     typedef typename UndirGraph::Edge Edge;
       
   124     checkConcept<concept::WriteMap<Node, int>, NodeMap>();
       
   125 
       
   126     typedef NullMap<Node, Edge> PredMap;
       
   127     typedef NullMap<Node, int> DistMap;
       
   128 
       
   129     int compNum = 0;
       
   130     typename Bfs<UndirGraph>::
       
   131       template DefPredMap<PredMap>::
       
   132       template DefDistMap<DistMap>::
       
   133       Create bfs(graph);
       
   134 
       
   135     PredMap predMap;
       
   136     bfs.predMap(predMap);
       
   137 
       
   138     DistMap distMap;
       
   139     bfs.distMap(distMap);
       
   140     
       
   141     bfs.init();
       
   142     for(typename UndirGraph::NodeIt n(graph); n != INVALID; ++n) {
       
   143       if(!bfs.reached(n)) {
       
   144 	bfs.addSource(n);
       
   145 	while (!bfs.emptyQueue()) {
       
   146 	  compMap.set(bfs.nextNode(), compNum);
       
   147 	  bfs.processNextNode();
       
   148 	}
       
   149 	++compNum;
       
   150       }
       
   151     }
       
   152     return compNum;
       
   153   }
       
   154 
    37   namespace _topology_bits {
   155   namespace _topology_bits {
    38     
   156 
    39     template <typename NodeMap>
   157     template <typename Graph, typename Iterator >
    40     class BackCounterMap {
   158     struct LeaveOrderVisitor : public DfsVisitor<Graph> {
    41     public:
   159     public:
    42       BackCounterMap(NodeMap& _nodeMap, int _counter)
   160       typedef typename Graph::Node Node;
    43 	: nodeMap(_nodeMap), counter(_counter) {}
   161       LeaveOrderVisitor(Iterator it) : _it(it) {}
    44 
   162 
    45       void set(typename NodeMap::Key key, bool val) {
   163       void leave(const Node& node) {
    46 	if (val) {
   164 	*(_it++) = node;
    47 	  nodeMap.set(key, --counter);
       
    48 	} else {
       
    49 	  nodeMap.set(key, -1);
       
    50 	}
       
    51       }
       
    52 
       
    53       bool operator[](typename NodeMap::Key key) const {
       
    54 	return nodeMap[key] != -1;
       
    55       }
   165       }
    56 
   166 
    57     private:
   167     private:
    58       NodeMap& nodeMap;
   168       Iterator _it;
    59       int counter;
       
    60     };
   169     };
    61   }
   170 
    62 
   171     template <typename Graph, typename Map>
    63   // \todo Its to special output // ReadWriteMap
   172     struct FillMapVisitor : public DfsVisitor<Graph> {
       
   173     public:
       
   174       typedef typename Graph::Node Node;
       
   175       typedef typename Map::Value Value;
       
   176 
       
   177       FillMapVisitor(Map& map, Value& value) 
       
   178 	: _map(map), _value(value) {}
       
   179 
       
   180       void reach(const Node& node) {
       
   181 	_map.set(node, _value);
       
   182       }
       
   183     private:
       
   184       Map& _map;
       
   185       Value& _value;
       
   186     };
       
   187 
       
   188     template <typename Graph, typename EdgeMap>
       
   189     struct StronglyConnectedCutEdgesVisitor : public DfsVisitor<Graph> {
       
   190     public:
       
   191       typedef typename Graph::Node Node;
       
   192       typedef typename Graph::Edge Edge;
       
   193 
       
   194       StronglyConnectedCutEdgesVisitor(const Graph& graph, EdgeMap& cutMap, 
       
   195 				       int& cutNum) 
       
   196 	: _graph(graph), _cutMap(cutMap), _cutNum(cutNum), 
       
   197 	  _compMap(graph), _num(0) {
       
   198       }
       
   199 
       
   200       void stop(const Node&) {
       
   201 	++_num;
       
   202       }
       
   203 
       
   204       void reach(const Node& node) {
       
   205 	_compMap.set(node, _num);
       
   206       }
       
   207 
       
   208       void examine(const Edge& edge) {
       
   209  	if (_compMap[_graph.source(edge)] != _compMap[_graph.target(edge)]) {
       
   210  	  _cutMap.set(edge, true);
       
   211  	  ++_cutNum;
       
   212  	}
       
   213       }
       
   214     private:
       
   215       const Graph& _graph;
       
   216       EdgeMap& _cutMap;
       
   217       int& _cutNum;
       
   218 
       
   219       typename Graph::template NodeMap<int> _compMap;
       
   220       int _num;
       
   221     };
       
   222 
       
   223   }
       
   224 
       
   225 
       
   226   /// \ingroup topology
       
   227   ///
       
   228   /// \brief Check that the given directed graph is strongly connected.
       
   229   ///
       
   230   /// Check that the given directed graph is strongly connected. The
       
   231   /// graph is strongly connected when any two nodes of the graph are
       
   232   /// connected with directed pathes in both direction.
       
   233   /// \return %False when the graph is not strongly connected.
       
   234   /// \see connected
       
   235   ///
       
   236   /// \waning Empty graph is not strongly connected.
       
   237   template <typename Graph>
       
   238   bool stronglyConnected(const Graph& graph) {
       
   239     checkConcept<concept::StaticGraph, Graph>();
       
   240     if (NodeIt(graph) == INVALID) return false;
       
   241 
       
   242     typedef typename Graph::Node Node;
       
   243     typedef typename Graph::NodeIt NodeIt;
       
   244 
       
   245     using namespace _topology_bits;
       
   246 
       
   247     typedef DfsVisitor<Graph> Visitor;
       
   248     Visitor visitor;
       
   249 
       
   250     DfsVisit<Graph, Visitor> dfs(graph, visitor);
       
   251     dfs.init();
       
   252     dfs.addSource(NodeIt(graph));
       
   253     dfs.start();
       
   254 
       
   255     for (NodeIt it(graph); it != INVALID; ++it) {
       
   256       if (!dfs.reached(it)) {
       
   257 	return false;
       
   258       }
       
   259     }
       
   260 
       
   261     typedef RevGraphAdaptor<const Graph> RGraph;
       
   262     RGraph rgraph(graph);
       
   263 
       
   264     typedef DfsVisitor<Graph> RVisitor;
       
   265     RVisitor rvisitor;
       
   266 
       
   267     DfsVisit<RGraph, RVisitor> rdfs(rgraph, rvisitor);
       
   268     rdfs.init();    
       
   269     rdfs.addSource(NodeIt(graph));
       
   270     rdfs.start();
       
   271 
       
   272     for (NodeIt it(graph); it != INVALID; ++it) {
       
   273       if (!rdfs.reached(it)) {
       
   274 	return false;
       
   275       }
       
   276     }
       
   277 
       
   278     return true;
       
   279   }
       
   280 
       
   281   /// \ingroup topology
       
   282   ///
       
   283   /// \brief Count the strongly connected components of a directed graph
       
   284   ///
       
   285   /// Count the strongly connected components of a directed graph.
       
   286   /// The strongly connected components are the classes of an equivalence
       
   287   /// relation on the nodes of the graph. Two nodes are connected with
       
   288   /// directed paths in both direction.
       
   289   ///
       
   290   /// \param g The graph.
       
   291   /// \return The number of components
       
   292   template <typename Graph>
       
   293   int countStronglyConnectedComponents(const Graph& graph) {
       
   294     checkConcept<concept::StaticGraph, Graph>();
       
   295 
       
   296     using namespace _topology_bits;
       
   297 
       
   298     typedef typename Graph::Node Node;
       
   299     typedef typename Graph::Edge Edge;
       
   300     typedef typename Graph::NodeIt NodeIt;
       
   301     typedef typename Graph::EdgeIt EdgeIt;
       
   302     
       
   303     typedef std::vector<Node> Container;
       
   304     typedef typename Container::iterator Iterator;
       
   305 
       
   306     Container nodes(countNodes(graph));
       
   307     typedef LeaveOrderVisitor<Graph, Iterator> Visitor;
       
   308     Visitor visitor(nodes.begin());
       
   309       
       
   310     DfsVisit<Graph, Visitor> dfs(graph, visitor);
       
   311     dfs.init();
       
   312     for (NodeIt it(graph); it != INVALID; ++it) {
       
   313       if (!dfs.reached(it)) {
       
   314 	dfs.addSource(it);
       
   315 	dfs.start();
       
   316       }
       
   317     }
       
   318 
       
   319     typedef typename Container::reverse_iterator RIterator;
       
   320     typedef RevGraphAdaptor<const Graph> RGraph;
       
   321 
       
   322     RGraph rgraph(graph);
       
   323 
       
   324     typedef DfsVisitor<Graph> RVisitor;
       
   325     RVisitor rvisitor;
       
   326 
       
   327     DfsVisit<RGraph, RVisitor> rdfs(rgraph, rvisitor);
       
   328 
       
   329     int compNum = 0;
       
   330 
       
   331     rdfs.init();
       
   332     for (RIterator it = nodes.rbegin(); it != nodes.rend(); ++it) {
       
   333       if (!rdfs.reached(*it)) {
       
   334 	rdfs.addSource(*it);
       
   335 	rdfs.start();
       
   336 	++compNum;
       
   337       }
       
   338     }
       
   339     return compNum;
       
   340   }
       
   341 
       
   342   /// \ingroup topology
       
   343   ///
       
   344   /// \brief Find the strongly connected components of a directed graph
       
   345   ///
       
   346   /// Find the strongly connected components of a directed graph.
       
   347   /// The strongly connected components are the classes of an equivalence
       
   348   /// relation on the nodes of the graph. Two nodes are in relationship
       
   349   /// when there are directed paths between them in both direction.
       
   350   ///
       
   351   /// \param g The graph.
       
   352   /// \retval comp A writable node map. The values will be set from 0 to
       
   353   /// the number of the strongly connected components minus one. Each values 
       
   354   /// of the map will be set exactly once, the values of a certain component 
       
   355   /// will be set continuously.
       
   356   /// \return The number of components
    64   template <typename Graph, typename NodeMap>
   357   template <typename Graph, typename NodeMap>
    65   bool topological_sort(const Graph& graph, NodeMap& nodeMap) {
   358   int stronglyConnectedComponents(const Graph& graph, NodeMap& compMap) {
       
   359     checkConcept<concept::StaticGraph, Graph>();
       
   360     typedef typename Graph::Node Node;
       
   361     typedef typename Graph::NodeIt NodeIt;
       
   362     checkConcept<concept::WriteMap<Node, int>, NodeMap>();
       
   363 
    66     using namespace _topology_bits;
   364     using namespace _topology_bits;
    67 
   365     
       
   366     typedef std::vector<Node> Container;
       
   367     typedef typename Container::iterator Iterator;
       
   368 
       
   369     Container nodes(countNodes(graph));
       
   370     typedef LeaveOrderVisitor<Graph, Iterator> Visitor;
       
   371     Visitor visitor(nodes.begin());
       
   372       
       
   373     DfsVisit<Graph, Visitor> dfs(graph, visitor);
       
   374     dfs.init();
       
   375     for (NodeIt it(graph); it != INVALID; ++it) {
       
   376       if (!dfs.reached(it)) {
       
   377 	dfs.addSource(it);
       
   378 	dfs.start();
       
   379       }
       
   380     }
       
   381 
       
   382     typedef typename Container::reverse_iterator RIterator;
       
   383     typedef RevGraphAdaptor<const Graph> RGraph;
       
   384 
       
   385     RGraph rgraph(graph);
       
   386 
       
   387     int compNum = 0;
       
   388 
       
   389     typedef FillMapVisitor<RGraph, NodeMap> RVisitor;
       
   390     RVisitor rvisitor(compMap, compNum);
       
   391 
       
   392     DfsVisit<RGraph, RVisitor> rdfs(rgraph, rvisitor);
       
   393 
       
   394     rdfs.init();
       
   395     for (RIterator it = nodes.rbegin(); it != nodes.rend(); ++it) {
       
   396       if (!rdfs.reached(*it)) {
       
   397 	rdfs.addSource(*it);
       
   398 	rdfs.start();
       
   399 	++compNum;
       
   400       }
       
   401     }
       
   402     return compNum;
       
   403   }
       
   404 
       
   405   /// \ingroup topology
       
   406   ///
       
   407   /// \brief Find the cut edges of the strongly connected components.
       
   408   ///
       
   409   /// Find the cut edges of the strongly connected components.
       
   410   /// The strongly connected components are the classes of an equivalence
       
   411   /// relation on the nodes of the graph. Two nodes are in relationship
       
   412   /// when there are directed paths between them in both direction.
       
   413   /// The strongly connected components are separated by the cut edges.
       
   414   ///
       
   415   /// \param g The graph.
       
   416   /// \retval comp A writable edge map. The values will be set true when
       
   417   /// the edge is cut edge otherwise false.
       
   418   ///
       
   419   /// \return The number of cut edges
       
   420   template <typename Graph, typename EdgeMap>
       
   421   int stronglyConnectedCutEdges(const Graph& graph, EdgeMap& cutMap) {
    68     checkConcept<concept::StaticGraph, Graph>();
   422     checkConcept<concept::StaticGraph, Graph>();
    69     checkConcept<concept::ReadWriteMap<typename Graph::Node, int>, NodeMap>();
   423     typedef typename Graph::Node Node;
       
   424     typedef typename Graph::Edge Edge;
       
   425     typedef typename Graph::NodeIt NodeIt;
       
   426     checkConcept<concept::WriteMap<Edge, bool>, EdgeMap>();
       
   427 
       
   428     using namespace _topology_bits;
       
   429     
       
   430     typedef std::vector<Node> Container;
       
   431     typedef typename Container::iterator Iterator;
       
   432 
       
   433     Container nodes(countNodes(graph));
       
   434     typedef LeaveOrderVisitor<Graph, Iterator> Visitor;
       
   435     Visitor visitor(nodes.begin());
       
   436       
       
   437     DfsVisit<Graph, Visitor> dfs(graph, visitor);
       
   438     dfs.init();
       
   439     for (NodeIt it(graph); it != INVALID; ++it) {
       
   440       if (!dfs.reached(it)) {
       
   441 	dfs.addSource(it);
       
   442 	dfs.start();
       
   443       }
       
   444     }
       
   445 
       
   446     typedef typename Container::reverse_iterator RIterator;
       
   447     typedef RevGraphAdaptor<const Graph> RGraph;
       
   448 
       
   449     RGraph rgraph(graph);
       
   450 
       
   451     int cutNum = 0;
       
   452 
       
   453     typedef StronglyConnectedCutEdgesVisitor<RGraph, EdgeMap> RVisitor;
       
   454     RVisitor rvisitor(rgraph, cutMap, cutNum);
       
   455 
       
   456     DfsVisit<RGraph, RVisitor> rdfs(rgraph, rvisitor);
       
   457 
       
   458     rdfs.init();
       
   459     for (RIterator it = nodes.rbegin(); it != nodes.rend(); ++it) {
       
   460       if (!rdfs.reached(*it)) {
       
   461 	rdfs.addSource(*it);
       
   462 	rdfs.start();
       
   463       }
       
   464     }
       
   465     return cutNum;
       
   466   }
       
   467 
       
   468   namespace _topology_bits {
       
   469     
       
   470     template <typename Graph>
       
   471     class CountNodeBiconnectedComponentsVisitor : public DfsVisitor<Graph> {
       
   472     public:
       
   473       typedef typename Graph::Node Node;
       
   474       typedef typename Graph::Edge Edge;
       
   475       typedef typename Graph::UndirEdge UndirEdge;
       
   476 
       
   477       CountNodeBiconnectedComponentsVisitor(const Graph& graph, int &compNum) 
       
   478 	: _graph(graph), _compNum(compNum), 
       
   479 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   480 
       
   481       void start(const Node& node) {
       
   482 	_predMap.set(node, INVALID);
       
   483       }
       
   484       
       
   485       void reach(const Node& node) {
       
   486 	_numMap.set(node, _num);
       
   487 	_retMap.set(node, _num);
       
   488 	++_num;
       
   489       }
       
   490 
       
   491       void discover(const Edge& edge) {
       
   492 	_predMap.set(_graph.target(edge), _graph.source(edge));
       
   493       }
       
   494 
       
   495       void examine(const Edge& edge) {
       
   496 	if (_graph.source(edge) == _graph.target(edge) && 
       
   497 	    _graph.direction(edge)) {
       
   498 	  ++_compNum;
       
   499 	  return;
       
   500 	}
       
   501 	if (_predMap[_graph.source(edge)] == _graph.target(edge)) {
       
   502 	  return;
       
   503 	}
       
   504 	if (_retMap[_graph.source(edge)] > _numMap[_graph.target(edge)]) {
       
   505 	  _retMap.set(_graph.source(edge), _numMap[_graph.target(edge)]);
       
   506 	}
       
   507       }
       
   508 
       
   509       void backtrack(const Edge& edge) {
       
   510 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   511 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   512 	}  
       
   513 	if (_numMap[_graph.source(edge)] <= _retMap[_graph.target(edge)]) {
       
   514 	  ++_compNum;
       
   515 	}
       
   516       }
       
   517       
       
   518     private:
       
   519       const Graph& _graph;
       
   520       int& _compNum; 
       
   521 
       
   522       typename Graph::template NodeMap<int> _numMap;
       
   523       typename Graph::template NodeMap<int> _retMap;
       
   524       typename Graph::template NodeMap<Node> _predMap;
       
   525       int _num;
       
   526     };
       
   527 
       
   528     template <typename Graph, typename EdgeMap>
       
   529     class NodeBiconnectedComponentsVisitor : public DfsVisitor<Graph> {
       
   530     public:
       
   531       typedef typename Graph::Node Node;
       
   532       typedef typename Graph::Edge Edge;
       
   533       typedef typename Graph::UndirEdge UndirEdge;
       
   534 
       
   535       NodeBiconnectedComponentsVisitor(const Graph& graph, 
       
   536 				       EdgeMap& compMap, int &compNum) 
       
   537 	: _graph(graph), _compMap(compMap), _compNum(compNum), 
       
   538 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   539 
       
   540       void start(const Node& node) {
       
   541 	_predMap.set(node, INVALID);
       
   542       }
       
   543       
       
   544       void reach(const Node& node) {
       
   545 	_numMap.set(node, _num);
       
   546 	_retMap.set(node, _num);
       
   547 	++_num;
       
   548       }
       
   549 
       
   550       void discover(const Edge& edge) {
       
   551 	Node target = _graph.target(edge);
       
   552 	_predMap.set(target, edge);
       
   553 	_edgeStack.push(edge);
       
   554       }
       
   555 
       
   556       void examine(const Edge& edge) {
       
   557 	Node source = _graph.source(edge);
       
   558 	Node target = _graph.target(edge);
       
   559 	if (source == target && _graph.direction(edge)) {
       
   560 	  _compMap.set(edge, _compNum);
       
   561 	  ++_compNum;
       
   562 	  return;
       
   563 	}
       
   564 	if (_numMap[target] < _numMap[source]) {
       
   565 	  if (_predMap[source] != _graph.oppositeEdge(edge)) {
       
   566 	    _edgeStack.push(edge);
       
   567 	  }
       
   568 	}
       
   569 	if (_predMap[source] != INVALID && 
       
   570 	    target == _graph.source(_predMap[source])) {
       
   571 	  return;
       
   572 	}
       
   573 	if (_retMap[source] > _numMap[target]) {
       
   574 	  _retMap.set(source, _numMap[target]);
       
   575 	}
       
   576       }
       
   577 
       
   578       void backtrack(const Edge& edge) {
       
   579 	Node source = _graph.source(edge);
       
   580 	Node target = _graph.target(edge);
       
   581 	if (_retMap[source] > _retMap[target]) {
       
   582 	  _retMap.set(source, _retMap[target]);
       
   583 	}  
       
   584 	if (_numMap[source] <= _retMap[target]) {
       
   585 	  while (_edgeStack.top() != edge) {
       
   586 	    _compMap.set(_edgeStack.top(), _compNum);
       
   587 	    _edgeStack.pop();
       
   588 	  }
       
   589 	  _compMap.set(edge, _compNum);
       
   590 	  _edgeStack.pop();
       
   591 	  ++_compNum;
       
   592 	}
       
   593       }
       
   594       
       
   595     private:
       
   596       const Graph& _graph;
       
   597       EdgeMap& _compMap;
       
   598       int& _compNum; 
       
   599 
       
   600       typename Graph::template NodeMap<int> _numMap;
       
   601       typename Graph::template NodeMap<int> _retMap;
       
   602       typename Graph::template NodeMap<Edge> _predMap;
       
   603       std::stack<UndirEdge> _edgeStack;
       
   604       int _num;
       
   605     };
       
   606 
       
   607 
       
   608     template <typename Graph, typename NodeMap>
       
   609     class NodeBiconnectedCutNodesVisitor : public DfsVisitor<Graph> {
       
   610     public:
       
   611       typedef typename Graph::Node Node;
       
   612       typedef typename Graph::Edge Edge;
       
   613       typedef typename Graph::UndirEdge UndirEdge;
       
   614 
       
   615       NodeBiconnectedCutNodesVisitor(const Graph& graph, NodeMap& cutMap,
       
   616 				     int& cutNum) 
       
   617 	: _graph(graph), _cutMap(cutMap), _cutNum(cutNum),
       
   618 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   619 
       
   620       void start(const Node& node) {
       
   621 	_predMap.set(node, INVALID);
       
   622 	rootCut = false;
       
   623       }
       
   624       
       
   625       void reach(const Node& node) {
       
   626 	_numMap.set(node, _num);
       
   627 	_retMap.set(node, _num);
       
   628 	++_num;
       
   629       }
       
   630 
       
   631       void discover(const Edge& edge) {
       
   632 	_predMap.set(_graph.target(edge), _graph.source(edge));
       
   633       }
       
   634 
       
   635       void examine(const Edge& edge) {
       
   636 	if (_graph.source(edge) == _graph.target(edge) && 
       
   637 	    _graph.direction(edge)) {
       
   638 	  if (!_cutMap[_graph.source(edge)]) {
       
   639 	    _cutMap.set(_graph.source(edge), true);
       
   640 	    ++_cutNum;
       
   641 	  }
       
   642 	  return;
       
   643 	}
       
   644 	if (_predMap[_graph.source(edge)] == _graph.target(edge)) return;
       
   645 	if (_retMap[_graph.source(edge)] > _numMap[_graph.target(edge)]) {
       
   646 	  _retMap.set(_graph.source(edge), _numMap[_graph.target(edge)]);
       
   647 	}
       
   648       }
       
   649 
       
   650       void backtrack(const Edge& edge) {
       
   651 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   652 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   653 	}  
       
   654 	if (_numMap[_graph.source(edge)] <= _retMap[_graph.target(edge)]) {
       
   655 	  if (_predMap[_graph.source(edge)] != INVALID) {
       
   656 	    if (!_cutMap[_graph.source(edge)]) {
       
   657 	      _cutMap.set(_graph.source(edge), true);
       
   658 	      ++_cutNum;
       
   659 	    }
       
   660 	  } else if (rootCut) {
       
   661 	    if (!_cutMap[_graph.source(edge)]) {
       
   662 	      _cutMap.set(_graph.source(edge), true);
       
   663 	      ++_cutNum;
       
   664 	    }
       
   665 	  } else {
       
   666 	    rootCut = true;
       
   667 	  }
       
   668 	}
       
   669       }
       
   670       
       
   671     private:
       
   672       const Graph& _graph;
       
   673       NodeMap& _cutMap;
       
   674       int& _cutNum; 
       
   675 
       
   676       typename Graph::template NodeMap<int> _numMap;
       
   677       typename Graph::template NodeMap<int> _retMap;
       
   678       typename Graph::template NodeMap<Node> _predMap;
       
   679       std::stack<UndirEdge> _edgeStack;
       
   680       int _num;
       
   681       bool rootCut;
       
   682     };
       
   683 
       
   684   }
       
   685 
       
   686   template <typename UndirGraph>
       
   687   int countNodeBiconnectedComponents(const UndirGraph& graph);
       
   688 
       
   689   /// \ingroup topology
       
   690   ///
       
   691   /// \brief Checks the graph is node biconnected.
       
   692   ///
       
   693   /// This function checks that the undirected graph is node biconnected  
       
   694   /// graph. The graph is node biconnected if any two undirected edge is 
       
   695   /// on same circle.
       
   696   ///
       
   697   /// \param graph The graph.
       
   698   /// \return %True when the graph node biconnected.
       
   699   /// \todo Make it faster.
       
   700   template <typename UndirGraph>
       
   701   bool nodeBiconnected(const UndirGraph& graph) {
       
   702     return countNodeBiconnectedComponents(graph) == 1;
       
   703   }
       
   704 
       
   705   /// \ingroup topology
       
   706   ///
       
   707   /// \brief Count the biconnected components.
       
   708   ///
       
   709   /// This function finds the node biconnected components in an undirected 
       
   710   /// graph. The biconnected components are the classes of an equivalence 
       
   711   /// relation on the undirected edges. Two undirected edge is in relationship
       
   712   /// when they are on same circle.
       
   713   ///
       
   714   /// \param graph The graph.
       
   715   /// \return The number of components.
       
   716   template <typename UndirGraph>
       
   717   int countNodeBiconnectedComponents(const UndirGraph& graph) {
       
   718     checkConcept<concept::UndirGraph, UndirGraph>();
       
   719     typedef typename UndirGraph::NodeIt NodeIt;
       
   720 
       
   721     using namespace _topology_bits;
       
   722 
       
   723     typedef CountNodeBiconnectedComponentsVisitor<UndirGraph> Visitor;
       
   724 
       
   725     int compNum = 0;
       
   726     Visitor visitor(graph, compNum);
       
   727 
       
   728     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
   729     dfs.init();
       
   730     
       
   731     for (NodeIt it(graph); it != INVALID; ++it) {
       
   732       if (!dfs.reached(it)) {
       
   733 	dfs.addSource(it);
       
   734 	dfs.start();
       
   735       }
       
   736     }
       
   737     return compNum;
       
   738   }
       
   739 
       
   740   /// \ingroup topology
       
   741   ///
       
   742   /// \brief Find the node biconnected components.
       
   743   ///
       
   744   /// This function finds the node biconnected components in an undirected 
       
   745   /// graph. The node biconnected components are the classes of an equivalence
       
   746   /// relation on the undirected edges. Two undirected edge are in relationship
       
   747   /// when they are on same circle.
       
   748   ///
       
   749   /// \param graph The graph.
       
   750   /// \retval comp A writable undir edge map. The values will be set from 0 to
       
   751   /// the number of the biconnected components minus one. Each values 
       
   752   /// of the map will be set exactly once, the values of a certain component 
       
   753   /// will be set continuously.
       
   754   /// \return The number of components.
       
   755   template <typename UndirGraph, typename UndirEdgeMap>
       
   756   int nodeBiconnectedComponents(const UndirGraph& graph, 
       
   757 				UndirEdgeMap& compMap) {
       
   758     checkConcept<concept::UndirGraph, UndirGraph>();
       
   759     typedef typename UndirGraph::NodeIt NodeIt;
       
   760     typedef typename UndirGraph::UndirEdge UndirEdge;
       
   761     checkConcept<concept::WriteMap<UndirEdge, int>, UndirEdgeMap>();
       
   762 
       
   763     using namespace _topology_bits;
       
   764 
       
   765     typedef NodeBiconnectedComponentsVisitor<UndirGraph, UndirEdgeMap> Visitor;
       
   766     
       
   767     int compNum = 0;
       
   768     Visitor visitor(graph, compMap, compNum);
       
   769 
       
   770     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
   771     dfs.init();
       
   772     
       
   773     for (NodeIt it(graph); it != INVALID; ++it) {
       
   774       if (!dfs.reached(it)) {
       
   775 	dfs.addSource(it);
       
   776 	dfs.start();
       
   777       }
       
   778     }
       
   779     return compNum;
       
   780   }
       
   781 
       
   782   /// \ingroup topology
       
   783   ///
       
   784   /// \brief Find the node biconnected cut nodes.
       
   785   ///
       
   786   /// This function finds the node biconnected cut nodes in an undirected 
       
   787   /// graph. The node biconnected components are the classes of an equivalence
       
   788   /// relation on the undirected edges. Two undirected edges are in 
       
   789   /// relationship when they are on same circle. The biconnected components 
       
   790   /// are separted by nodes which are the cut nodes of the components.
       
   791   ///
       
   792   /// \param graph The graph.
       
   793   /// \retval comp A writable edge map. The values will be set true when
       
   794   /// the node separate two or more components.
       
   795   /// \return The number of the cut nodes.
       
   796   template <typename UndirGraph, typename NodeMap>
       
   797   int nodeBiconnectedCutNodes(const UndirGraph& graph, NodeMap& cutMap) {
       
   798     checkConcept<concept::UndirGraph, UndirGraph>();
       
   799     typedef typename UndirGraph::Node Node;
       
   800     typedef typename UndirGraph::NodeIt NodeIt;
       
   801     checkConcept<concept::WriteMap<Node, bool>, NodeMap>();
       
   802 
       
   803     using namespace _topology_bits;
       
   804 
       
   805     typedef NodeBiconnectedCutNodesVisitor<UndirGraph, NodeMap> Visitor;
       
   806     
       
   807     int cutNum = 0;
       
   808     Visitor visitor(graph, cutMap, cutNum);
       
   809 
       
   810     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
   811     dfs.init();
       
   812     
       
   813     for (NodeIt it(graph); it != INVALID; ++it) {
       
   814       if (!dfs.reached(it)) {
       
   815 	dfs.addSource(it);
       
   816 	dfs.start();
       
   817       }
       
   818     }
       
   819     return cutNum;
       
   820   }
       
   821 
       
   822   namespace _topology_bits {
       
   823     
       
   824     template <typename Graph>
       
   825     class CountEdgeBiconnectedComponentsVisitor : public DfsVisitor<Graph> {
       
   826     public:
       
   827       typedef typename Graph::Node Node;
       
   828       typedef typename Graph::Edge Edge;
       
   829       typedef typename Graph::UndirEdge UndirEdge;
       
   830 
       
   831       CountEdgeBiconnectedComponentsVisitor(const Graph& graph, int &compNum) 
       
   832 	: _graph(graph), _compNum(compNum), 
       
   833 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   834 
       
   835       void start(const Node& node) {
       
   836 	_predMap.set(node, INVALID);
       
   837       }
       
   838       
       
   839       void reach(const Node& node) {
       
   840 	_numMap.set(node, _num);
       
   841 	_retMap.set(node, _num);
       
   842 	++_num;
       
   843       }
       
   844       
       
   845       void leave(const Node& node) {
       
   846 	if (_numMap[node] <= _retMap[node]) {
       
   847 	  ++_compNum;
       
   848 	}	
       
   849       }
       
   850 
       
   851       void discover(const Edge& edge) {
       
   852 	_predMap.set(_graph.target(edge), edge);
       
   853       }
       
   854 
       
   855       void examine(const Edge& edge) {
       
   856 	if (_predMap[_graph.source(edge)] == _graph.oppositeEdge(edge)) {
       
   857 	  return;
       
   858 	}
       
   859 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   860 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   861 	}
       
   862       }
       
   863 
       
   864       void backtrack(const Edge& edge) {
       
   865 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   866 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   867 	}  
       
   868       }
       
   869       
       
   870     private:
       
   871       const Graph& _graph;
       
   872       int& _compNum; 
       
   873 
       
   874       typename Graph::template NodeMap<int> _numMap;
       
   875       typename Graph::template NodeMap<int> _retMap;
       
   876       typename Graph::template NodeMap<Edge> _predMap;
       
   877       int _num;
       
   878     };
       
   879 
       
   880     template <typename Graph, typename NodeMap>
       
   881     class EdgeBiconnectedComponentsVisitor : public DfsVisitor<Graph> {
       
   882     public:
       
   883       typedef typename Graph::Node Node;
       
   884       typedef typename Graph::Edge Edge;
       
   885       typedef typename Graph::UndirEdge UndirEdge;
       
   886 
       
   887       EdgeBiconnectedComponentsVisitor(const Graph& graph, 
       
   888 				       NodeMap& compMap, int &compNum) 
       
   889 	: _graph(graph), _compMap(compMap), _compNum(compNum), 
       
   890 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   891 
       
   892       void start(const Node& node) {
       
   893 	_predMap.set(node, INVALID);
       
   894       }
       
   895       
       
   896       void reach(const Node& node) {
       
   897 	_numMap.set(node, _num);
       
   898 	_retMap.set(node, _num);
       
   899 	_nodeStack.push(node);
       
   900 	++_num;
       
   901       }
       
   902       
       
   903       void leave(const Node& node) {
       
   904 	if (_numMap[node] <= _retMap[node]) {
       
   905 	  while (_nodeStack.top() != node) {
       
   906 	    _compMap.set(_nodeStack.top(), _compNum);
       
   907 	    _nodeStack.pop();
       
   908 	  }
       
   909 	  _compMap.set(node, _compNum);
       
   910 	  _nodeStack.pop();
       
   911 	  ++_compNum;
       
   912 	}	
       
   913       }
       
   914 
       
   915       void discover(const Edge& edge) {
       
   916 	_predMap.set(_graph.target(edge), edge);
       
   917       }
       
   918 
       
   919       void examine(const Edge& edge) {
       
   920 	if (_predMap[_graph.source(edge)] == _graph.oppositeEdge(edge)) {
       
   921 	  return;
       
   922 	}
       
   923 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   924 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   925 	}
       
   926       }
       
   927 
       
   928       void backtrack(const Edge& edge) {
       
   929 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   930 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   931 	}  
       
   932       }
       
   933       
       
   934     private:
       
   935       const Graph& _graph;
       
   936       NodeMap& _compMap;
       
   937       int& _compNum; 
       
   938 
       
   939       typename Graph::template NodeMap<int> _numMap;
       
   940       typename Graph::template NodeMap<int> _retMap;
       
   941       typename Graph::template NodeMap<Edge> _predMap;
       
   942       std::stack<Node> _nodeStack;
       
   943       int _num;
       
   944     };
       
   945 
       
   946 
       
   947     template <typename Graph, typename EdgeMap>
       
   948     class EdgeBiconnectedCutEdgesVisitor : public DfsVisitor<Graph> {
       
   949     public:
       
   950       typedef typename Graph::Node Node;
       
   951       typedef typename Graph::Edge Edge;
       
   952       typedef typename Graph::UndirEdge UndirEdge;
       
   953 
       
   954       EdgeBiconnectedCutEdgesVisitor(const Graph& graph, 
       
   955 				     EdgeMap& cutMap, int &cutNum) 
       
   956 	: _graph(graph), _cutMap(cutMap), _cutNum(cutNum), 
       
   957 	  _numMap(graph), _retMap(graph), _predMap(graph), _num(0) {}
       
   958 
       
   959       void start(const Node& node) {
       
   960 	_predMap[node] = INVALID;
       
   961       }
       
   962       
       
   963       void reach(const Node& node) {
       
   964 	_numMap.set(node, _num);
       
   965 	_retMap.set(node, _num);
       
   966 	++_num;
       
   967       }
       
   968       
       
   969       void leave(const Node& node) {
       
   970 	if (_numMap[node] <= _retMap[node]) {
       
   971 	  if (_predMap[node] != INVALID) {
       
   972 	    _cutMap.set(_predMap[node], true);
       
   973 	    ++_cutNum;
       
   974 	  }
       
   975 	}	
       
   976       }
       
   977 
       
   978       void discover(const Edge& edge) {
       
   979 	_predMap.set(_graph.target(edge), edge);
       
   980       }
       
   981 
       
   982       void examine(const Edge& edge) {
       
   983 	if (_predMap[_graph.source(edge)] == _graph.oppositeEdge(edge)) {
       
   984 	  return;
       
   985 	}
       
   986 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   987 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   988 	}
       
   989       }
       
   990 
       
   991       void backtrack(const Edge& edge) {
       
   992 	if (_retMap[_graph.source(edge)] > _retMap[_graph.target(edge)]) {
       
   993 	  _retMap.set(_graph.source(edge), _retMap[_graph.target(edge)]);
       
   994 	}  
       
   995       }
       
   996       
       
   997     private:
       
   998       const Graph& _graph;
       
   999       EdgeMap& _cutMap;
       
  1000       int& _cutNum; 
       
  1001 
       
  1002       typename Graph::template NodeMap<int> _numMap;
       
  1003       typename Graph::template NodeMap<int> _retMap;
       
  1004       typename Graph::template NodeMap<Edge> _predMap;
       
  1005       int _num;
       
  1006     };
       
  1007   }
       
  1008 
       
  1009   template <typename UndirGraph>
       
  1010   int countEdgeBiconnectedComponents(const UndirGraph& graph);
       
  1011 
       
  1012   /// \ingroup topology
       
  1013   ///
       
  1014   /// \brief Checks that the graph is edge biconnected.
       
  1015   ///
       
  1016   /// This function checks that the graph is edge biconnected. The undirected
       
  1017   /// graph is edge biconnected when any two nodes are connected with two
       
  1018   /// edge-disjoint paths.
       
  1019   ///
       
  1020   /// \param graph The undirected graph.
       
  1021   /// \return The number of components.
       
  1022   /// \todo Make it faster.
       
  1023   template <typename UndirGraph>
       
  1024   bool edgeBiconnected(const UndirGraph& graph) { 
       
  1025     return countEdgeBiconnectedComponents(graph) == 1;
       
  1026   }
       
  1027 
       
  1028   /// \ingroup topology
       
  1029   ///
       
  1030   /// \brief Count the edge biconnected components.
       
  1031   ///
       
  1032   /// This function count the edge biconnected components in an undirected 
       
  1033   /// graph. The edge biconnected components are the classes of an equivalence
       
  1034   /// relation on the nodes. Two nodes are in relationship when they are  
       
  1035   /// connected with at least two edge-disjoint paths.
       
  1036   ///
       
  1037   /// \param graph The undirected graph.
       
  1038   /// \return The number of components.
       
  1039   template <typename UndirGraph>
       
  1040   int countEdgeBiconnectedComponents(const UndirGraph& graph) { 
       
  1041     checkConcept<concept::UndirGraph, UndirGraph>();
       
  1042     typedef typename UndirGraph::NodeIt NodeIt;
       
  1043 
       
  1044     using namespace _topology_bits;
       
  1045 
       
  1046     typedef CountEdgeBiconnectedComponentsVisitor<UndirGraph> Visitor;
       
  1047     
       
  1048     int compNum = 0;
       
  1049     Visitor visitor(graph, compNum);
       
  1050 
       
  1051     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
  1052     dfs.init();
       
  1053     
       
  1054     for (NodeIt it(graph); it != INVALID; ++it) {
       
  1055       if (!dfs.reached(it)) {
       
  1056 	dfs.addSource(it);
       
  1057 	dfs.start();
       
  1058       }
       
  1059     }
       
  1060     return compNum;
       
  1061   }
       
  1062 
       
  1063   /// \ingroup topology
       
  1064   ///
       
  1065   /// \brief Find the edge biconnected components.
       
  1066   ///
       
  1067   /// This function finds the edge biconnected components in an undirected 
       
  1068   /// graph. The edge biconnected components are the classes of an equivalence
       
  1069   /// relation on the nodes. Two nodes are in relationship when they are  
       
  1070   /// connected at least two edge-disjoint paths.
       
  1071   ///
       
  1072   /// \param graph The graph.
       
  1073   /// \retval comp A writable node map. The values will be set from 0 to
       
  1074   /// the number of the biconnected components minus one. Each values 
       
  1075   /// of the map will be set exactly once, the values of a certain component 
       
  1076   /// will be set continuously.
       
  1077   /// \return The number of components.
       
  1078   template <typename UndirGraph, typename NodeMap>
       
  1079   int edgeBiconnectedComponents(const UndirGraph& graph, NodeMap& compMap) { 
       
  1080     checkConcept<concept::UndirGraph, UndirGraph>();
       
  1081     typedef typename UndirGraph::NodeIt NodeIt;
       
  1082     typedef typename UndirGraph::Node Node;
       
  1083     checkConcept<concept::WriteMap<Node, int>, NodeMap>();
       
  1084 
       
  1085     using namespace _topology_bits;
       
  1086 
       
  1087     typedef EdgeBiconnectedComponentsVisitor<UndirGraph, NodeMap> Visitor;
       
  1088     
       
  1089     int compNum = 0;
       
  1090     Visitor visitor(graph, compMap, compNum);
       
  1091 
       
  1092     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
  1093     dfs.init();
       
  1094     
       
  1095     for (NodeIt it(graph); it != INVALID; ++it) {
       
  1096       if (!dfs.reached(it)) {
       
  1097 	dfs.addSource(it);
       
  1098 	dfs.start();
       
  1099       }
       
  1100     }
       
  1101     return compNum;
       
  1102   }
       
  1103 
       
  1104   /// \ingroup topology
       
  1105   ///
       
  1106   /// \brief Find the edge biconnected cut edges.
       
  1107   ///
       
  1108   /// This function finds the edge biconnected components in an undirected 
       
  1109   /// graph. The edge biconnected components are the classes of an equivalence
       
  1110   /// relation on the nodes. Two nodes are in relationship when they are 
       
  1111   /// connected with at least two edge-disjoint paths. The edge biconnected 
       
  1112   /// components are separted by edges which are the cut edges of the 
       
  1113   /// components.
       
  1114   ///
       
  1115   /// \param graph The graph.
       
  1116   /// \retval comp A writable node map. The values will be set true when the
       
  1117   /// edge is a cut edge.
       
  1118   /// \return The number of cut edges.
       
  1119   template <typename UndirGraph, typename UndirEdgeMap>
       
  1120   int edgeBiconnectedCutEdges(const UndirGraph& graph, UndirEdgeMap& cutMap) { 
       
  1121     checkConcept<concept::UndirGraph, UndirGraph>();
       
  1122     typedef typename UndirGraph::NodeIt NodeIt;
       
  1123     typedef typename UndirGraph::UndirEdge UndirEdge;
       
  1124     checkConcept<concept::WriteMap<UndirEdge, bool>, UndirEdgeMap>();
       
  1125 
       
  1126     using namespace _topology_bits;
       
  1127 
       
  1128     typedef EdgeBiconnectedCutEdgesVisitor<UndirGraph, UndirEdgeMap> Visitor;
       
  1129     
       
  1130     int cutNum = 0;
       
  1131     Visitor visitor(graph, cutMap, cutNum);
       
  1132 
       
  1133     DfsVisit<UndirGraph, Visitor> dfs(graph, visitor);
       
  1134     dfs.init();
       
  1135     
       
  1136     for (NodeIt it(graph); it != INVALID; ++it) {
       
  1137       if (!dfs.reached(it)) {
       
  1138 	dfs.addSource(it);
       
  1139 	dfs.start();
       
  1140       }
       
  1141     }
       
  1142     return cutNum;
       
  1143   }
       
  1144 
       
  1145 
       
  1146   namespace _topology_bits {
       
  1147     
       
  1148     template <typename Graph, typename IntNodeMap>
       
  1149     class TopologicalSortVisitor : public DfsVisitor<Graph> {
       
  1150     public:
       
  1151       typedef typename Graph::Node Node;
       
  1152       typedef typename Graph::Edge edge;
       
  1153 
       
  1154       TopologicalSortVisitor(IntNodeMap& order, int num) 
       
  1155 	: _order(order), _num(num) {}
       
  1156       
       
  1157       void leave(const Node& node) {
       
  1158 	_order.set(node, --_num);
       
  1159       }
       
  1160 
       
  1161     private:
       
  1162       IntNodeMap& _order;
       
  1163       int _num;
       
  1164     };
       
  1165     
       
  1166   }
       
  1167 
       
  1168   /// \ingroup topology
       
  1169   ///
       
  1170   /// \brief Sort the nodes of a DAG into topolgical order.
       
  1171   ///
       
  1172   /// Sort the nodes of a DAG into topolgical order.
       
  1173   ///
       
  1174   /// \param g The graph. In must be directed and acyclic.
       
  1175   /// \retval comp A writable node map. The values will be set from 0 to
       
  1176   /// the number of the nodes in the graph minus one. Each values of the map
       
  1177   /// will be set exactly once, the values  will be set descending order.
       
  1178   ///
       
  1179   /// \see checkedTopologicalSort
       
  1180   /// \see dag
       
  1181   template <typename Graph, typename NodeMap>
       
  1182   void topologicalSort(const Graph& graph, NodeMap& order) {
       
  1183     using namespace _topology_bits;
       
  1184 
       
  1185     checkConcept<concept::StaticGraph, Graph>();
       
  1186     checkConcept<concept::WriteMap<typename Graph::Node, int>, NodeMap>();
    70 
  1187 
    71     typedef typename Graph::Node Node;
  1188     typedef typename Graph::Node Node;
    72     typedef typename Graph::NodeIt NodeIt;
  1189     typedef typename Graph::NodeIt NodeIt;
    73     typedef typename Graph::Edge Edge;
  1190     typedef typename Graph::Edge Edge;
    74 
  1191 
    75     typedef BackCounterMap<NodeMap> ProcessedMap;
  1192     TopologicalSortVisitor<Graph, NodeMap> 
       
  1193       visitor(order, countNodes(graph)); 
       
  1194 
       
  1195     DfsVisit<Graph, TopologicalSortVisitor<Graph, NodeMap> >
       
  1196       dfs(graph, visitor);
       
  1197 
       
  1198     dfs.init();
       
  1199     for (NodeIt it(graph); it != INVALID; ++it) {
       
  1200       if (!dfs.reached(it)) {
       
  1201 	dfs.addSource(it);
       
  1202 	dfs.start();
       
  1203       }
       
  1204     }    
       
  1205   }
       
  1206 
       
  1207   /// \ingroup topology
       
  1208   ///
       
  1209   /// \brief Sort the nodes of a DAG into topolgical order.
       
  1210   ///
       
  1211   /// Sort the nodes of a DAG into topolgical order. It also checks
       
  1212   /// that the given graph is DAG.
       
  1213   ///
       
  1214   /// \param g The graph. In must be directed and acyclic.
       
  1215   /// \retval order A readable - writable node map. The values will be set 
       
  1216   /// from 0 to the number of the nodes in the graph minus one. Each values 
       
  1217   /// of the map will be set exactly once, the values will be set descending 
       
  1218   /// order.
       
  1219   /// \return %False when the graph is not DAG.
       
  1220   ///
       
  1221   /// \see topologicalSort
       
  1222   /// \see dag
       
  1223   template <typename Graph, typename NodeMap>
       
  1224   bool checkedTopologicalSort(const Graph& graph, NodeMap& order) {
       
  1225     using namespace _topology_bits;
       
  1226 
       
  1227     checkConcept<concept::StaticGraph, Graph>();
       
  1228     checkConcept<concept::ReadWriteMap<typename Graph::Node, int>, NodeMap>();
       
  1229 
       
  1230     typedef typename Graph::Node Node;
       
  1231     typedef typename Graph::NodeIt NodeIt;
       
  1232     typedef typename Graph::Edge Edge;
       
  1233 
       
  1234     order = constMap<Node, int, -1>();
       
  1235 
       
  1236     TopologicalSortVisitor<Graph, NodeMap> 
       
  1237       visitor(order, countNodes(graph)); 
       
  1238 
       
  1239     DfsVisit<Graph, TopologicalSortVisitor<Graph, NodeMap> >
       
  1240       dfs(graph, visitor);
       
  1241 
       
  1242     dfs.init();
       
  1243     for (NodeIt it(graph); it != INVALID; ++it) {
       
  1244       if (!dfs.reached(it)) {
       
  1245 	dfs.addSource(it);
       
  1246 	while (!dfs.emptyQueue()) {
       
  1247  	  Edge edge = dfs.nextEdge();
       
  1248  	  Node target = graph.target(edge);
       
  1249  	  if (dfs.reached(target) && order[target] == -1) {
       
  1250  	    return false;
       
  1251  	  }
       
  1252  	  dfs.processNextEdge();
       
  1253  	}
       
  1254       }
       
  1255     }
       
  1256     return true;
       
  1257   }
       
  1258 
       
  1259   /// \ingroup topology
       
  1260   ///
       
  1261   /// \brief Check that the given directed graph is a DAG.
       
  1262   ///
       
  1263   /// Check that the given directed graph is a DAG. The DAG is
       
  1264   /// an Directed Acyclic Graph.
       
  1265   /// \return %False when the graph is not DAG.
       
  1266   /// \see acyclic
       
  1267   template <typename Graph>
       
  1268   bool dag(const Graph& graph) {
       
  1269 
       
  1270     checkConcept<concept::StaticGraph, Graph>();
       
  1271 
       
  1272     typedef typename Graph::Node Node;
       
  1273     typedef typename Graph::NodeIt NodeIt;
       
  1274     typedef typename Graph::Edge Edge;
       
  1275 
       
  1276     typedef typename Graph::template NodeMap<bool> ProcessedMap;
    76 
  1277 
    77     typename Dfs<Graph>::template DefProcessedMap<ProcessedMap>::
  1278     typename Dfs<Graph>::template DefProcessedMap<ProcessedMap>::
    78       Create dfs(graph);
  1279       Create dfs(graph);
    79 
  1280 
    80     ProcessedMap processed(nodeMap, countNodes(graph));
  1281     ProcessedMap processed(graph);
    81 
       
    82     dfs.processedMap(processed);
  1282     dfs.processedMap(processed);
       
  1283 
    83     dfs.init();
  1284     dfs.init();
    84     for (NodeIt it(graph); it != INVALID; ++it) {
  1285     for (NodeIt it(graph); it != INVALID; ++it) {
    85       if (!dfs.reached(it)) {
  1286       if (!dfs.reached(it)) {
    86 	dfs.addSource(it);
  1287 	dfs.addSource(it);
    87 	while (!dfs.emptyQueue()) {
  1288 	while (!dfs.emptyQueue()) {
    95       }
  1296       }
    96     }    
  1297     }    
    97     return true;
  1298     return true;
    98   }
  1299   }
    99 
  1300 
   100   /// \brief Check that the given graph is a DAG.
  1301   /// \ingroup topology
   101   ///
  1302   ///
   102   /// Check that the given graph is a DAG. The DAG is
       
   103   /// an Directed Acyclic Graph.
       
   104   template <typename Graph>
       
   105   bool dag(const Graph& graph) {
       
   106 
       
   107     checkConcept<concept::StaticGraph, Graph>();
       
   108 
       
   109     typedef typename Graph::Node Node;
       
   110     typedef typename Graph::NodeIt NodeIt;
       
   111     typedef typename Graph::Edge Edge;
       
   112 
       
   113     typedef typename Graph::template NodeMap<bool> ProcessedMap;
       
   114 
       
   115     typename Dfs<Graph>::template DefProcessedMap<ProcessedMap>::
       
   116       Create dfs(graph);
       
   117 
       
   118     ProcessedMap processed(graph);
       
   119     dfs.processedMap(processed);
       
   120 
       
   121     dfs.init();
       
   122     for (NodeIt it(graph); it != INVALID; ++it) {
       
   123       if (!dfs.reached(it)) {
       
   124 	dfs.addSource(it);
       
   125 	while (!dfs.emptyQueue()) {
       
   126 	  Edge edge = dfs.nextEdge();
       
   127 	  Node target = graph.target(edge);
       
   128 	  if (dfs.reached(target) && !processed[target]) {
       
   129 	    return false;
       
   130 	  }
       
   131 	  dfs.processNextEdge();
       
   132 	}
       
   133       }
       
   134     }    
       
   135     return true;
       
   136   }
       
   137 
       
   138   // UndirGraph algorithms
       
   139 
       
   140   /// \brief Check that the given undirected graph is connected.
       
   141   ///
       
   142   /// Check that the given undirected graph connected.
       
   143   template <typename UndirGraph>
       
   144   bool connected(const UndirGraph& graph) {
       
   145     checkConcept<concept::UndirGraph, UndirGraph>();
       
   146     typedef typename UndirGraph::NodeIt NodeIt;
       
   147     if (NodeIt(graph) == INVALID) return false;
       
   148     Dfs<UndirGraph> dfs(graph);
       
   149     dfs.run(NodeIt(graph));
       
   150     for (NodeIt it(graph); it != INVALID; ++it) {
       
   151       if (!dfs.reached(it)) {
       
   152 	return false;
       
   153       }
       
   154     }
       
   155     return true;
       
   156   }
       
   157 
       
   158   /// \brief Check that the given undirected graph is acyclic.
  1303   /// \brief Check that the given undirected graph is acyclic.
   159   ///
  1304   ///
   160   /// Check that the given undirected graph acyclic.
  1305   /// Check that the given undirected graph acyclic.
       
  1306   /// \param graph The undirected graph.
       
  1307   /// \return %True when there is no circle in the graph.
       
  1308   /// \see dag
   161   template <typename UndirGraph>
  1309   template <typename UndirGraph>
   162   bool acyclic(const UndirGraph& graph) {
  1310   bool acyclic(const UndirGraph& graph) {
   163     checkConcept<concept::UndirGraph, UndirGraph>();
  1311     checkConcept<concept::UndirGraph, UndirGraph>();
   164     typedef typename UndirGraph::Node Node;
  1312     typedef typename UndirGraph::Node Node;
   165     typedef typename UndirGraph::NodeIt NodeIt;
  1313     typedef typename UndirGraph::NodeIt NodeIt;
   182       }
  1330       }
   183     }
  1331     }
   184     return true;
  1332     return true;
   185   }
  1333   }
   186 
  1334 
       
  1335   /// \ingroup topology
       
  1336   ///
   187   /// \brief Check that the given undirected graph is tree.
  1337   /// \brief Check that the given undirected graph is tree.
   188   ///
  1338   ///
   189   /// Check that the given undirected graph is tree.
  1339   /// Check that the given undirected graph is tree.
       
  1340   /// \param graph The undirected graph.
       
  1341   /// \return %True when the graph is acyclic and connected.
   190   template <typename UndirGraph>
  1342   template <typename UndirGraph>
   191   bool tree(const UndirGraph& graph) {
  1343   bool tree(const UndirGraph& graph) {
   192     checkConcept<concept::UndirGraph, UndirGraph>();
  1344     checkConcept<concept::UndirGraph, UndirGraph>();
   193     typedef typename UndirGraph::Node Node;
  1345     typedef typename UndirGraph::Node Node;
   194     typedef typename UndirGraph::NodeIt NodeIt;
  1346     typedef typename UndirGraph::NodeIt NodeIt;
   195     typedef typename UndirGraph::Edge Edge;
  1347     typedef typename UndirGraph::Edge Edge;
   196     if (NodeIt(graph) == INVALID) return false;
       
   197     Dfs<UndirGraph> dfs(graph);
  1348     Dfs<UndirGraph> dfs(graph);
   198     dfs.init();
  1349     dfs.init();
   199     dfs.addSource(NodeIt(graph));
  1350     dfs.addSource(NodeIt(graph));
   200     while (!dfs.emptyQueue()) {
  1351     while (!dfs.emptyQueue()) {
   201       Edge edge = dfs.nextEdge();
  1352       Edge edge = dfs.nextEdge();
   212 	return false;
  1363 	return false;
   213       }
  1364       }
   214     }    
  1365     }    
   215     return true;
  1366     return true;
   216   }
  1367   }
   217  
  1368 
   218   ///Count the number of connected components of an undirected graph
  1369   /// \ingroup topology
   219 
  1370   ///
   220   ///Count the number of connected components of an undirected graph
  1371   /// \brief Check that the given undirected graph is bipartite.
   221   ///
  1372   ///
   222   ///\param g The graph. In must be undirected.
  1373   /// Check that the given undirected graph is bipartite.
   223   ///\return The number of components
  1374   /// \param graph The undirected graph.
   224   template <class UndirGraph>
  1375   /// \return %True when the nodes can be separated into two sets that
   225   int countConnectedComponents(const UndirGraph &g) {
  1376   /// there are not connected nodes in neither sets.
       
  1377   template <typename UndirGraph>
       
  1378   bool bipartite(const UndirGraph& graph) {
   226     checkConcept<concept::UndirGraph, UndirGraph>();
  1379     checkConcept<concept::UndirGraph, UndirGraph>();
   227     int c = 0;
  1380     typedef typename UndirGraph::Node Node;
   228     Bfs<UndirGraph> bfs(g);
  1381     typedef typename UndirGraph::NodeIt NodeIt;
   229     bfs.init();
  1382     typedef typename UndirGraph::Edge Edge;
   230     for(typename UndirGraph::NodeIt n(g); n != INVALID; ++n) {
  1383     if (NodeIt(graph) == INVALID) return false;
   231       if(!bfs.reached(n)) {
  1384     Dfs<UndirGraph> dfs(graph);
   232 	bfs.addSource(n);
  1385     dfs.init();
   233 	bfs.start();
  1386     typename UndirGraph::template NodeMap<bool> red(graph);
   234 	++c;
       
   235       }
       
   236     }
       
   237     return c;
       
   238   }
       
   239 
       
   240 
       
   241   ///Find the connected components of an undirected graph
       
   242 
       
   243   ///Find the connected components of an undirected graph
       
   244   ///
       
   245   ///\param g The graph. In must be undirected.
       
   246   ///\retval comp A writable node map. The values will be set from 0 to
       
   247   ///the number of the connected components minus one. Each values of the map
       
   248   ///will be set exactly once, the values of a certain component will be
       
   249   ///set continuously.
       
   250   ///\return The number of components
       
   251   ///\todo Test required
       
   252   template <class UndirGraph, class IntNodeMap>
       
   253   int connectedComponents(const UndirGraph &g, IntNodeMap &comp) {
       
   254     checkConcept<concept::UndirGraph, UndirGraph>();
       
   255     checkConcept<concept::WriteMap<typename UndirGraph::Node, int>, 
       
   256       IntNodeMap>();
       
   257     int c = 0;
       
   258     Bfs<UndirGraph> bfs(g);
       
   259     bfs.init();
       
   260     for(typename UndirGraph::NodeIt n(g); n != INVALID; ++n) {
       
   261       if(!bfs.reached(n)) {
       
   262 	bfs.addSource(n);
       
   263 	while (!bfs.emptyQueue()) {
       
   264 	  comp[bfs.nextNode()] = c;
       
   265 	  bfs.processNextNode();
       
   266 	}
       
   267 	++c;
       
   268       }
       
   269     }
       
   270     return c;
       
   271   }
       
   272 
       
   273   namespace _components_bits {
       
   274 
       
   275     template <typename Key, typename IntMap>
       
   276     struct FillWriteMap : public MapBase<Key, bool> {
       
   277     public:
       
   278       FillWriteMap(IntMap& _map, int& _comp) 
       
   279 	: map(_map), comp(_comp) {}
       
   280       void set(Key key, bool value) {
       
   281 	if (value) { map.set(key, comp); }
       
   282       }
       
   283     private:
       
   284       IntMap& map;
       
   285       int& comp;
       
   286     };
       
   287 
       
   288     template <typename Key, typename Container = std::vector<Key> >
       
   289     struct BackInserterWriteMap : public MapBase<Key, bool> {
       
   290     public:
       
   291       BackInserterWriteMap(Container& _container) 
       
   292 	: container(_container) {}
       
   293       void set(Key key, bool value) {
       
   294 	if (value) { container.push_back(key); }
       
   295       }
       
   296     private:
       
   297       Container& container;
       
   298     };
       
   299 
       
   300   }
       
   301 
       
   302   /// \brief Count the strongly connected components of a directed graph
       
   303   ///
       
   304   /// Count the strongly connected components of a directed graph
       
   305   ///
       
   306   /// \param g The graph.
       
   307   /// \return The number of components
       
   308   template <typename Graph>
       
   309   int countStronglyConnectedComponents(const Graph& graph) {
       
   310     checkConcept<concept::StaticGraph, Graph>();
       
   311 
       
   312     using namespace _components_bits;
       
   313 
       
   314     typedef typename Graph::Node Node;
       
   315     typedef typename Graph::Edge Edge;
       
   316     typedef typename Graph::NodeIt NodeIt;
       
   317     typedef typename Graph::EdgeIt EdgeIt;
       
   318     
       
   319 
       
   320     typename Dfs<Graph>::
       
   321       template DefProcessedMap<BackInserterWriteMap<Node> >::
       
   322       Create dfs(graph);
       
   323 
       
   324     std::vector<Node> nodes;
       
   325     BackInserterWriteMap<Node> processed(nodes);
       
   326     dfs.processedMap(processed);
       
   327 
       
   328     dfs.init();
       
   329     for (NodeIt it(graph); it != INVALID; ++it) {
  1387     for (NodeIt it(graph); it != INVALID; ++it) {
   330       if (!dfs.reached(it)) {
  1388       if (!dfs.reached(it)) {
   331 	dfs.addSource(it);
  1389 	dfs.addSource(it);
   332 	dfs.start();
  1390 	red[it] = true;
   333       }
  1391 	while (!dfs.emptyQueue()) {
   334     }
  1392 	  Edge edge = dfs.nextEdge();
   335 
  1393 	  Node source = graph.source(edge);
   336     typedef RevGraphAdaptor<const Graph> RGraph;
  1394 	  Node target = graph.target(edge);
   337 
  1395 	  if (dfs.reached(target) && red[source] == red[target]) {
   338     RGraph rgraph(graph);
  1396 	    return false;
   339 
  1397 	  } else {
   340     Dfs<RGraph> rdfs(rgraph);
  1398 	    red[target] = !red[source];
   341 
  1399 	  }
   342     int num = 0;
  1400 	  dfs.processNextEdge();
   343 
  1401 	}
   344     rdfs.init();
  1402       }
   345     for (typename std::vector<Node>::reverse_iterator 
  1403     }
   346 	   it = nodes.rbegin(); it != nodes.rend(); ++it) {
  1404     return true;
   347       if (!rdfs.reached(*it)) {
  1405   }
   348 	rdfs.addSource(*it);
  1406    
   349 	rdfs.start();
       
   350 	++num;
       
   351       }
       
   352     }
       
   353     return num;
       
   354   }
       
   355 
       
   356   /// \brief Find the strongly connected components of a directed graph
       
   357   ///
       
   358   /// Find the strongly connected components of a directed graph
       
   359   ///
       
   360   /// \param g The graph.
       
   361   /// \retval comp A writable node map. The values will be set from 0 to
       
   362   /// the number of the strongly connected components minus one. Each values 
       
   363   /// of the map will be set exactly once, the values of a certain component 
       
   364   /// will be set continuously.
       
   365   /// \return The number of components
       
   366   template <typename Graph, typename IntNodeMap>
       
   367   int stronglyConnectedComponents(const Graph& graph, IntNodeMap& comp) {
       
   368     checkConcept<concept::StaticGraph, Graph>();
       
   369     checkConcept<concept::WriteMap<typename Graph::Node, int>, IntNodeMap>();
       
   370 
       
   371     using namespace _components_bits;
       
   372 
       
   373     typedef typename Graph::Node Node;
       
   374     typedef typename Graph::Edge Edge;
       
   375     typedef typename Graph::NodeIt NodeIt;
       
   376     typedef typename Graph::EdgeIt EdgeIt;
       
   377     
       
   378 
       
   379     typename Dfs<Graph>::
       
   380       template DefProcessedMap<BackInserterWriteMap<Node> >::
       
   381       Create dfs(graph);
       
   382 
       
   383     std::vector<Node> nodes;
       
   384     BackInserterWriteMap<Node> processed(nodes);
       
   385     dfs.processedMap(processed);
       
   386 
       
   387     dfs.init();
       
   388     for (NodeIt it(graph); it != INVALID; ++it) {
       
   389       if (!dfs.reached(it)) {
       
   390 	dfs.addSource(it);
       
   391 	dfs.start();
       
   392       }
       
   393     }
       
   394 
       
   395     typedef RevGraphAdaptor<const Graph> RGraph;
       
   396 
       
   397     RGraph rgraph(graph);
       
   398 
       
   399     typename Dfs<RGraph>::
       
   400       template DefProcessedMap<FillWriteMap<Node, IntNodeMap> >::
       
   401       Create rdfs(rgraph);
       
   402 
       
   403     int num = 0;
       
   404     FillWriteMap<Node, IntNodeMap> rprocessed(comp, num);
       
   405     rdfs.processedMap(rprocessed);
       
   406 
       
   407     rdfs.init();
       
   408     for (typename std::vector<Node>::reverse_iterator 
       
   409 	   it = nodes.rbegin(); it != nodes.rend(); ++it) {
       
   410       if (!rdfs.reached(*it)) {
       
   411 	rdfs.addSource(*it);
       
   412 	rdfs.start();
       
   413 	++num;
       
   414       }
       
   415     }
       
   416     return num;
       
   417   }
       
   418 
       
   419 } //namespace lemon
  1407 } //namespace lemon
   420 
  1408 
   421 #endif //LEMON_TOPOLOGY_H
  1409 #endif //LEMON_TOPOLOGY_H