// -*- c++ -*-

 #ifndef HUGO_DIMACS_H

 #define HUGO_DIMACS_H

 #include <iostream>

 #include <string>

 #include <vector>

 namespace hugo {

   /// Dimacs flow files.

   /// This function reads a flow instance from dimacs flow format.

   /// At the beginning \c g is destroyed by \c g.clear().

   /// If the data coming from \c is is a max flow innstance, then 

   /// \c s and \t will be respectively the source and target nodes 

   /// and \c capacity will contain the edge capacities.

   /// If the data is a shortest path problem then \c s will be the 

   /// source node and \capacity will contain the edge lengths.

   template<typename Graph, typename CapacityMap>

   void readDimacsMaxFlow(std::istream& is, Graph &g, typename Graph::Node &s, typename Graph::Node &t, CapacityMap& capacity) {

     g.clear();

     int cap;

     char d;

     std::string problem;

     char c;

     int i, j;

     std::string str;

     int n, m; 

     typename Graph::Edge e;

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

     while (is>>c) {

       switch (c) {

       case 'c': //comment

 	getline(is, str);

 	break;

       case 'p': //problem definition

 	is >> problem >> n >> m;

 	getline(is, str);

 	nodes.resize(n+1);

 	for (int k=1; k<=n; ++k) nodes[k]=g.addNode();

 	break;

       case 'n': //node definition

 	if (problem=="sp") { //shortest path problem

 	  is >> i;

 	  getline(is, str);

 	  s=nodes[i];

 	}

 	if (problem=="max") { //max flow problem

 	  is >> i >> d;

 	  getline(is, str);

 	  if (d=='s') s=nodes[i];

 	  if (d=='t') t=nodes[i];

 	}

 	break;

       case 'a':

 	is >> i >> j >> cap;

 	getline(is, str);

 	e=g.addEdge(nodes[i], nodes[j]);

 	capacity.update();

 	capacity.set(e, cap);

 	break;

       }

     }

   }

 } //namespace hugo

 #endif //HUGO_DIMACS_H