source: lemon-0.x/src/hugo/dimacs.h @ 549:5531429143bc

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

#include <iostream>
#include <string>
#include <vector>
#include <hugo/maps.h>

/// \file
/// \brief Dimacs file format reader.

namespace hugo {

  /// Dimacs flow file format reader function.

  /// This function reads a flow instance from dimacs flow format.
  /// At the beginning \c g is cleared by \c g.clear().
  /// If the data coming from \c is is a max flow problem instance, then 
  /// \c s and \c 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 instance then \c s will be the 
  /// source node and \c capacity will contain the edge lengths.
  ///
  ///\author Marton Makai
  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;
      }
    }
  }

  /// matching problem
  template<typename Graph>
  void readDimacs(std::istream& is, Graph &g) {
    typename Graph::Node u;
    NullMap<typename Graph::Edge, int> n;
    readDimacs(is, g, n, u, u, n);
  }

  /// sg problem
  template<typename Graph, typename CapacityMap>
  void readDimacs(std::istream& is, Graph &g, CapacityMap& capacity) {
    typename Graph::Node u;
    NullMap<typename Graph::Edge, int> n;
    readDimacs(is, g, capacity, u, u, n);
  }

  /// shortest path problem
  template<typename Graph, typename CapacityMap>
  void readDimacs(std::istream& is, Graph &g, CapacityMap& capacity, 
                  typename Graph::Node &s) {
    NullMap<typename Graph::Edge, int> n;
    readDimacs(is, g, capacity, s, s, n);
  }

  /// max flow problem
  template<typename Graph, typename CapacityMap>
  void readDimacs(std::istream& is, Graph &g, CapacityMap& capacity, 
                  typename Graph::Node &s, typename Graph::Node &t) {
    NullMap<typename Graph::Edge, int> n;
    readDimacs(is, g, capacity, s, t, n);
  }

  /// min cost flow problem
  template<typename Graph, typename CapacityMap, typename CostMap>
  void readDimacs(std::istream& is, Graph &g, CapacityMap& capacity, 
                  typename Graph::Node &s, typename Graph::Node &t, 
                  CostMap& cost) {
    g.clear();
    typename CapacityMap::ValueType _cap;
    typename CostMap::ValueType _cost;
    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" || problem=="min") { //((max) or (min cost)) flow problem
          is >> i >> d;
          getline(is, str);
          if (d=='s') s=nodes[i];
          if (d=='t') t=nodes[i];
        }
        break;
      case 'a':
        if ( problem == "mat" ) {
          is >> i >> j;
          getline(is, str);
          g.addEdge(nodes[i], nodes[j]);
        }
        if ( problem == "max" || problem == "sp") {
          is >> i >> j >> _cap;
          getline(is, str);
          e=g.addEdge(nodes[i], nodes[j]);
          capacity.update();
          capacity.set(e, _cap);
        }
        if ( problem == "min" ) {
          is >> i >> j >> _cap >> _cost;
          getline(is, str);
          e=g.addEdge(nodes[i], nodes[j]);
          capacity.update();
          capacity.set(e, _cap);
          cost.update();
          cost.set(e, _cost);
        }
        break;
      }
    }
  }


  
  /// write matching problem
  template<typename Graph>
  void writeDimacs(std::ostream& os, const Graph &g) {
    typedef typename Graph::NodeIt NodeIt;
    typedef typename Graph::EdgeIt EdgeIt;  
    
    typename Graph::template NodeMap<int> nodes(g);

    os << "c matching problem" << std::endl;

    int i=1;
    NodeIt v;
    for(g.first(v); g.valid(v); g.next(v)) {
      nodes.set(v, i);
      ++i;
    }    
    
    os << "p mat " << g.nodeNum() << " " << g.edgeNum() << std::endl;

    EdgeIt e;
    for(g.first(e); g.valid(e); g.next(e)) {
      os << "a " << nodes[g.tail(e)] << " " << nodes[g.head(e)] << std::endl; 
    }

  }



} //namespace hugo

#endif //HUGO_DIMACS_H