src/work/marci/bipartite_graphs.h
changeset 493 bbd1db03f0fe
child 540 405ccc3105e1
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-1:000000000000 0:35bb5c1688bd
       
     1 // -*- c++ -*-
       
     2 #ifndef HUGO_BIPARTITE_GRAPHS_H
       
     3 #define HUGO_BIPARTITE_GRAPHS_H
       
     4 
       
     5 #include <bfs_iterator.h>
       
     6 #include <for_each_macros.h>
       
     7 
       
     8 namespace hugo {
       
     9 
       
    10   /// This function eat a read-write \c BoolMap& bool_map, 
       
    11   /// which have to work well up 
       
    12   /// to its \c set and \c operator[]() method. Thus we have to deal 
       
    13   /// very carefully with an uninitialized \c IterableBoolMap.
       
    14   template<typename Graph, typename BoolMap> 
       
    15   bool isBipartite(const Graph& g, BoolMap& bool_map) {
       
    16     typedef typename Graph::template NodeMap<bool> ReachedMap;
       
    17     ReachedMap reached(g/*, false*/);
       
    18     BfsIterator<Graph, ReachedMap> bfs(g, reached);
       
    19     FOR_EACH_LOC(typename Graph::NodeIt, n, g) {
       
    20       if (!reached[n]) {
       
    21 	bfs.pushAndSetReached(n);
       
    22 	bool_map.set(n, false) {
       
    23 	  while (!bfs.finished()) {
       
    24 	    if (bfs.isBNodeNewlyReached()) {
       
    25 	      bool_map.set(bfs.bNode())=!bfs.aNode();
       
    26 	    } else {
       
    27 	      if (bool_map[bfs.bNode()]==bool_map[bfs.aNode()]) {
       
    28 		return false;
       
    29 	      }
       
    30 	    }
       
    31 	    ++bfs;
       
    32 	  }
       
    33 	}
       
    34       }
       
    35     }
       
    36     return true;
       
    37   }
       
    38 }
       
    39 #endif //HUGO_BIPARTITE_GRAPHS_H