// -*- c++ -*-
#ifndef HUGO_BIPARTITE_GRAPHS_H
#define HUGO_BIPARTITE_GRAPHS_H

#include <bfs_iterator.h>
#include <for_each_macros.h>

namespace hugo {

  /// This function eat a read-write \c BoolMap& bool_map, 
  /// which have to work well up 
  /// to its \c set and \c operator[]() method. Thus we have to deal 
  /// very carefully with an uninitialized \c IterableBoolMap.
  template<typename Graph, typename BoolMap> 
  bool isBipartite(const Graph& g, BoolMap& bool_map) {
    typedef typename Graph::template NodeMap<bool> ReachedMap;
    ReachedMap reached(g/*, false*/);
    BfsIterator<Graph, ReachedMap> bfs(g, reached);
    FOR_EACH_LOC(typename Graph::NodeIt, n, g) {
      if (!reached[n]) {
	bfs.pushAndSetReached(n);
	bool_map.set(n, false) {
	  while (!bfs.finished()) {
	    if (bfs.isBNodeNewlyReached()) {
	      bool_map.set(bfs.bNode())=!bfs.aNode();
	    } else {
	      if (bool_map[bfs.bNode()]==bool_map[bfs.aNode()]) {
		return false;
	      }
	    }
	    ++bfs;
	  }
	}
      }
    }
    return true;
  }
}
#endif //HUGO_BIPARTITE_GRAPHS_H