#include <iostream> // For writing to the standard output.
#include <fstream> // For reading input files.

#include "graph.hpp"

int main(int argc, char** argv)
{
   if (argc != 2)
   {
      std::cout << "Expected one argument, found " << argc - 1 << std::endl;
      return EXIT_FAILURE; // return 1 would do the same, but is way too easy to mix up!
   }

   std::fstream input_file_graph{argv[1]};
   ED::Graph const graph = ED::Graph::read_dimacs(input_file_graph);

   ED::Graph greedy_matching_as_graph{graph.num_nodes()};
   for (ED::NodeId node_id = 0; node_id < graph.num_nodes(); ++node_id)
   {
      if (greedy_matching_as_graph.node(node_id).neighbors().empty())
      {
         for (ED::NodeId neighbor_id : graph.node(node_id).neighbors())
         {
            if (greedy_matching_as_graph.node(neighbor_id).neighbors().empty())
            {
               greedy_matching_as_graph.add_edge(node_id, neighbor_id);
               break; // Do not add more edges incident to this node!
            }
         }
      }
   }
   std::cout << greedy_matching_as_graph;
   return EXIT_SUCCESS; 
}