diff -r 2d6c8075d9d0 -r 818510fa3d99 src/lemon/suurballe.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lemon/suurballe.h	Wed Sep 29 15:30:04 2004 +0000
@@ -0,0 +1,215 @@
+/* -*- C++ -*-
+ * src/lemon/suurballe.h - Part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2004 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Combinatorial Optimization Research Group, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_SUURBALLE_H
+#define LEMON_SUURBALLE_H
+
+///\ingroup flowalgs
+///\file
+///\brief An algorithm for finding k paths of minimal total length.
+
+
+#include <lemon/maps.h>
+#include <vector>
+#include <lemon/min_cost_flow.h>
+
+namespace lemon {
+
+/// \addtogroup flowalgs
+/// @{
+
+  ///\brief Implementation of an algorithm for finding k edge-disjoint paths between 2 nodes 
+  /// of minimal total length 
+  ///
+  /// The class \ref lemon::Suurballe implements
+  /// an algorithm for finding k edge-disjoint paths
+  /// from a given source node to a given target node in an
+  /// edge-weighted directed graph having minimal total weight (length).
+  ///
+  ///\warning Length values should be nonnegative.
+  /// 
+  ///\param Graph The directed graph type the algorithm runs on.
+  ///\param LengthMap The type of the length map (values should be nonnegative).
+  ///
+  ///\note It it questionable if it is correct to call this method after
+  ///%Suurballe for it is just a special case of Edmond's and Karp's algorithm
+  ///for finding minimum cost flows. In fact, this implementation is just
+  ///wraps the MinCostFlow algorithms. The paper of both %Suurballe and
+  ///Edmonds-Karp published in 1972, therefore it is possibly right to
+  ///state that they are
+  ///independent results. Most frequently this special case is referred as
+  ///%Suurballe method in the literature, especially in communication
+  ///network context.
+  ///\author Attila Bernath
+  template <typename Graph, typename LengthMap>
+  class Suurballe{
+
+
+    typedef typename LengthMap::ValueType Length;
+    
+    typedef typename Graph::Node Node;
+    typedef typename Graph::NodeIt NodeIt;
+    typedef typename Graph::Edge Edge;
+    typedef typename Graph::OutEdgeIt OutEdgeIt;
+    typedef typename Graph::template EdgeMap<int> EdgeIntMap;
+
+    typedef ConstMap<Edge,int> ConstMap;
+
+    //Input
+    const Graph& G;
+
+    //Auxiliary variables
+    //This is the capacity map for the mincostflow problem
+    ConstMap const1map;
+    //This MinCostFlow instance will actually solve the problem
+    MinCostFlow<Graph, LengthMap, ConstMap> mincost_flow;
+
+    //Container to store found paths
+    std::vector< std::vector<Edge> > paths;
+
+  public :
+
+
+    /// The constructor of the class.
+    
+    ///\param _G The directed graph the algorithm runs on. 
+    ///\param _length The length (weight or cost) of the edges. 
+    Suurballe(Graph& _G, LengthMap& _length) : G(_G),
+      const1map(1), mincost_flow(_G, _length, const1map){}
+
+    ///Runs the algorithm.
+
+    ///Runs the algorithm.
+    ///Returns k if there are at least k edge-disjoint paths from s to t.
+    ///Otherwise it returns the number of found edge-disjoint paths from s to t.
+    ///
+    ///\param s The source node.
+    ///\param t The target node.
+    ///\param k How many paths are we looking for?
+    ///
+    int run(Node s, Node t, int k) {
+
+      int i = mincost_flow.run(s,t,k);
+    
+
+      //Let's find the paths
+      //We put the paths into stl vectors (as an inner representation). 
+      //In the meantime we lose the information stored in 'reversed'.
+      //We suppose the lengths to be positive now.
+
+      //We don't want to change the flow of mincost_flow, so we make a copy
+      //The name here suggests that the flow has only 0/1 values.
+      EdgeIntMap reversed(G); 
+
+      for(typename Graph::EdgeIt e(G); e!=INVALID; ++e) 
+	reversed[e] = mincost_flow.getFlow()[e];
+      
+      paths.clear();
+      //total_length=0;
+      paths.resize(k);
+      for (int j=0; j<i; ++j){
+	Node n=s;
+	OutEdgeIt e;
+
+	while (n!=t){
+
+
+	  G.first(e,n);
+	  
+	  while (!reversed[e]){
+	    ++e;
+	  }
+	  n = G.head(e);
+	  paths[j].push_back(e);
+	  //total_length += length[e];
+	  reversed[e] = 1-reversed[e];
+	}
+	
+      }
+      return i;
+    }
+
+    
+    ///Returns the total length of the paths
+    
+    ///This function gives back the total length of the found paths.
+    ///\pre \ref run() must
+    ///be called before using this function.
+    Length totalLength(){
+      return mincost_flow.totalLength();
+    }
+
+    ///Returns the found flow.
+
+    ///This function returns a const reference to the EdgeMap \c flow.
+    ///\pre \ref run() must
+    ///be called before using this function.
+    const EdgeIntMap &getFlow() const { return mincost_flow.flow;}
+
+    /// Returns the optimal dual solution
+    
+    ///This function returns a const reference to the NodeMap
+    ///\c potential (the dual solution).
+    /// \pre \ref run() must be called before using this function.
+    const EdgeIntMap &getPotential() const { return mincost_flow.potential;}
+
+    ///Checks whether the complementary slackness holds.
+
+    ///This function checks, whether the given solution is optimal.
+    ///It should return true after calling \ref run() 
+    ///Currently this function only checks optimality,
+    ///doesn't bother with feasibility
+    ///It is meant for testing purposes.
+    ///
+    bool checkComplementarySlackness(){
+      return mincost_flow.checkComplementarySlackness();
+    }
+
+    ///Read the found paths.
+    
+    ///This function gives back the \c j-th path in argument p.
+    ///Assumes that \c run() has been run and nothing changed since then.
+    /// \warning It is assumed that \c p is constructed to
+    ///be a path of graph \c G.
+    ///If \c j is not less than the result of previous \c run,
+    ///then the result here will be an empty path (\c j can be 0 as well).
+    ///
+    ///\param Path The type of the path structure to put the result to (must meet lemon path concept).
+    ///\param p The path to put the result to 
+    ///\param j Which path you want to get from the found paths (in a real application you would get the found paths iteratively)
+    template<typename Path>
+    void getPath(Path& p, size_t j){
+
+      p.clear();
+      if (j>paths.size()-1){
+	return;
+      }
+      typename Path::Builder B(p);
+      for(typename std::vector<Edge>::iterator i=paths[j].begin(); 
+	  i!=paths[j].end(); ++i ){
+	B.pushBack(*i);
+      }
+
+      B.commit();
+    }
+
+  }; //class Suurballe
+
+  ///@}
+
+} //namespace lemon
+
+#endif //LEMON_SUURBALLE_H