# HG changeset patch
# User athos
# Date 1084464018 0
# Node ID 305bd9c56f10fa775fe8242eec712cd9cdf8a474
# Parent  3f3e184252d27ca56761ac258be2ad1e25b76dca
Slight modifications.

diff -r 3f3e184252d2 -r 305bd9c56f10 src/hugo/mincostflows.h
--- a/src/hugo/mincostflows.h	Thu May 13 11:25:52 2004 +0000
+++ b/src/hugo/mincostflows.h	Thu May 13 16:00:18 2004 +0000
@@ -92,11 +92,6 @@
     //To store the potentila (dual variables)
     typename Graph::template NodeMap<Length> potential;
     
-    //Container to store found paths
-    //std::vector< std::vector<Edge> > paths;
-    //typedef DirPath<Graph> DPath;
-    //DPath paths;
-
 
     Length total_length;
 
@@ -151,6 +146,11 @@
 	  break;
 	};
 	
+	//We have to copy the potential
+	FOR_EACH_LOC(typename ResGraphType::NodeIt, n, res_graph){
+	  potential[n] += dijkstra.distMap()[n];
+	}
+	/*
 	{
 	  //We have to copy the potential
 	  typename ResGraphType::NodeIt n;
@@ -158,7 +158,7 @@
 	      potential[n] += dijkstra.distMap()[n];
 	  }
 	}
-
+	*/
 
 	//Augmenting on the sortest path
 	Node n=t;
@@ -225,25 +225,6 @@
       return true;
     }
     
-    /*
-      ///\todo To be implemented later
-
-    ///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 greater than the result of previous \c run, then the result here will be an empty path.
-    template<typename DirPath>
-    void getPath(DirPath& p, int j){
-      p.clear();
-      typename DirPath::Builder B(p);
-      for(typename std::vector<Edge>::iterator i=paths[j].begin(); 
-	  i!=paths[j].end(); ++i ){
-	B.pushBack(*i);
-      }
-
-      B.commit();
-    }
-
-    */
 
   }; //class MinCostFlows
 
@@ -251,4 +232,4 @@
 
 } //namespace hugo
 
-#endif //HUGO_MINCOSTFLOW_H
+#endif //HUGO_MINCOSTFLOWS_H
diff -r 3f3e184252d2 -r 305bd9c56f10 src/work/athos/mincostflow.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/work/athos/mincostflow.h	Thu May 13 16:00:18 2004 +0000
@@ -0,0 +1,245 @@
+// -*- c++ -*-
+#ifndef HUGO_MINCOSTFLOW_H
+#define HUGO_MINCOSTFLOW_H
+
+///\ingroup galgs
+///\file
+///\brief An algorithm for finding a flow of value \c k (for small values of \c k) having minimal total cost 
+
+
+#include <hugo/dijkstra.h>
+#include <hugo/graph_wrapper.h>
+#include <hugo/maps.h>
+#include <vector>
+#include <for_each_macros.h>
+
+namespace hugo {
+
+/// \addtogroup galgs
+/// @{
+
+  ///\brief Implementation of an algorithm for finding a flow of value \c k 
+  ///(for small values of \c k) having minimal total cost between 2 nodes 
+  /// 
+  ///
+  /// The class \ref hugo::MinCostFlow "MinCostFlow" implements
+  /// an algorithm for solving the following general minimum cost flow problem>
+  /// 
+  ///
+  ///
+  /// \warning It is assumed here that the problem has a feasible solution
+  ///
+  /// The range of the length (weight) function is nonnegative reals but 
+  /// the range of capacity function is the set of nonnegative integers. 
+  /// It is not a polinomial time algorithm for counting the minimum cost
+  /// maximal flow, since it counts the minimum cost flow for every value 0..M
+  /// where \c M is the value of the maximal flow.
+  ///
+  ///\author Attila Bernath
+  template <typename Graph, typename LengthMap, typename SupplyMap>
+  class MinCostFlow {
+
+    typedef typename LengthMap::ValueType Length;
+
+
+    typedef typename SupplyMap::ValueType Supply;
+    
+    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;
+
+    typedef ResGraphWrapper<const Graph,int,CapacityMap,EdgeIntMap> ResGraphType;
+    typedef typename ResGraphType::Edge ResGraphEdge;
+
+    class ModLengthMap {   
+      //typedef typename ResGraphType::template NodeMap<Length> NodeMap;
+      typedef typename Graph::template NodeMap<Length> NodeMap;
+      const ResGraphType& G;
+      //      const EdgeIntMap& rev;
+      const LengthMap &ol;
+      const NodeMap &pot;
+    public :
+      typedef typename LengthMap::KeyType KeyType;
+      typedef typename LengthMap::ValueType ValueType;
+	
+      ValueType operator[](typename ResGraphType::Edge e) const {     
+	if (G.forward(e))
+	  return  ol[e]-(pot[G.head(e)]-pot[G.tail(e)]);   
+	else
+	  return -ol[e]-(pot[G.head(e)]-pot[G.tail(e)]);   
+      }     
+	
+      ModLengthMap(const ResGraphType& _G,
+		   const LengthMap &o,  const NodeMap &p) : 
+	G(_G), /*rev(_rev),*/ ol(o), pot(p){}; 
+    };//ModLengthMap
+
+
+  protected:
+    
+    //Input
+    const Graph& G;
+    const LengthMap& length;
+    const SupplyMap& supply;//supply or demand of nodes
+
+
+    //auxiliary variables
+
+    //To store the flow
+    EdgeIntMap flow; 
+    //To store the potentila (dual variables)
+    typename Graph::template NodeMap<Length> potential;
+    //To store excess-deficit values
+    SupplyMap excess;
+    
+
+    Length total_length;
+
+
+  public :
+
+
+    MinCostFlow(Graph& _G, LengthMap& _length, SupplyMap& _supply) : G(_G), 
+      length(_length), supply(_supply), flow(_G), potential(_G){ }
+
+    
+    ///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.
+    ///\todo May be it does make sense to be able to start with a nonzero 
+    /// feasible primal-dual solution pair as well.
+    int run() {
+
+      //Resetting variables from previous runs
+      total_length = 0;
+      
+      FOR_EACH_LOC(typename Graph::EdgeIt, e, G){
+	flow.set(e,0);
+      }
+
+      //Initial value for delta
+      Supply delta = 0;
+      
+      FOR_EACH_LOC(typename Graph::NodeIt, n, G){
+	if (delta < abs(supply[e])){
+	  delta = abs(supply[e]);
+	}
+	excess.set(n,supply[e]);
+	//Initialize the copy of the Dijkstra potential to zero
+	potential.set(n,0);
+      }
+      
+
+      
+      //We need a residual graph which is uncapacitated
+      ResGraphType res_graph(G, flow);
+
+
+      
+      ModLengthMap mod_length(res_graph, length, potential);
+
+      Dijkstra<ResGraphType, ModLengthMap> dijkstra(res_graph, mod_length);
+
+
+      int i;
+      for (i=0; i<k; ++i){
+	dijkstra.run(s);
+	if (!dijkstra.reached(t)){
+	  //There are no k paths from s to t
+	  break;
+	};
+	
+	//We have to copy the potential
+	FOR_EACH_LOC(typename ResGraphType::NodeIt, n, res_graph){
+	  potential[n] += dijkstra.distMap()[n];
+	}
+
+	/*
+	{
+
+	  typename ResGraphType::NodeIt n;
+	  for ( res_graph.first(n) ; res_graph.valid(n) ; res_graph.next(n) ) {
+	      potential[n] += dijkstra.distMap()[n];
+	  }
+	}
+	*/
+
+	//Augmenting on the sortest path
+	Node n=t;
+	ResGraphEdge e;
+	while (n!=s){
+	  e = dijkstra.pred(n);
+	  n = dijkstra.predNode(n);
+	  res_graph.augment(e,delta);
+	  //Let's update the total length
+	  if (res_graph.forward(e))
+	    total_length += length[e];
+	  else 
+	    total_length -= length[e];	    
+	}
+
+	  
+      }
+      
+
+      return i;
+    }
+
+
+
+
+    ///This function gives back the total length of the found paths.
+    ///Assumes that \c run() has been run and nothing changed since then.
+    Length totalLength(){
+      return total_length;
+    }
+
+    ///Returns a const reference to the EdgeMap \c flow. \pre \ref run() must
+    ///be called before using this function.
+    const EdgeIntMap &getFlow() const { return flow;}
+
+  ///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 potential;}
+
+    ///This function checks, whether the given solution is optimal
+    ///Running after a \c run() should return with true
+    ///In this "state of the art" this only check optimality, doesn't bother with feasibility
+    ///
+    ///\todo Is this OK here?
+    bool checkComplementarySlackness(){
+      Length mod_pot;
+      Length fl_e;
+      FOR_EACH_LOC(typename Graph::EdgeIt, e, G){
+	//C^{\Pi}_{i,j}
+	mod_pot = length[e]-potential[G.head(e)]+potential[G.tail(e)];
+	fl_e = flow[e];
+	//	std::cout << fl_e << std::endl;
+	if (0<fl_e && fl_e<capacity[e]){
+	  if (mod_pot != 0)
+	    return false;
+	}
+	else{
+	  if (mod_pot > 0 && fl_e != 0)
+	    return false;
+	  if (mod_pot < 0 && fl_e != capacity[e])
+	    return false;
+	}
+      }
+      return true;
+    }
+    
+
+  }; //class MinCostFlow
+
+  ///@}
+
+} //namespace hugo
+
+#endif //HUGO_MINCOSTFLOW_H