// -*- c++ -*-

 #include <vector>

 #include <cstdlib>

 namespace hugo {

   /**

    * Inicializalja a veletlenszamgeneratort.

    * Figyelem, ez nem jo igazi random szamokhoz,

    * erre ne bizzad a titkaidat!

    */

   void random_init()

   {

     unsigned int seed = getpid();

     seed |= seed << 15;

     seed ^= time(0);

     srand(seed);

   }

   /**

    * Egy veletlen int-et ad vissza 0 es m-1 kozott.

    */

   int random(int m)

   {

     return int( double(m) * rand() / (RAND_MAX + 1.0) );

   }

   /// Generates a random graph with n nodes and m edges.

   /// Before generating the random graph, \c g.clear() is called.

   template<typename Graph>

   void randomGraph(Graph& g, int n, int m) {

     g.clear();

     std::vector<typename Graph::Node> nodes;

     for (int i=0; i<n; ++i)

       nodes.push_back(g.addNode());

     for (int i=0; i<m; ++i) 

       g.addEdge(nodes[random(n)], nodes[random(n)]);

   }

   /// Generates a random bipartite graph with a and b nodes 

   /// in the color classes and m edges.

   /// According to the bipartite graph concept, the resulting 

   /// graph is directed from the first class to the second one.

   /// Before generating the random graph, \c g.clear() is called.

   template<typename Graph>

   void randomBipartiteGraph(Graph& g, int a, int b, int m) {

     g.clear();

     std::vector<typename Graph::Node> s_nodes;

     std::vector<typename Graph::Node> t_nodes;

     for (int i=0; i<a; ++i)

       ///\bug g.addNode(g.S_CLASS) would be better.

       s_nodes.push_back(g.addNode(false));

     for (int i=0; i<b; ++i)

       ///\bug g.addNode(g.T_CLASS) would be better.

       t_nodes.push_back(g.addNode(true));

     for (int i=0; i<m; ++i) 

       g.addEdge(s_nodes[random(a)], t_nodes[random(b)]);

   }

 } //namespace hugo