athos@36: #ifndef PREFLOW_PUSH_HH
athos@36: #define PREFLOW_PUSH_HH
athos@36: 
athos@36: #include <algorithm>
athos@36: #include <list>
athos@36: #include <vector>
athos@36: //#include "pf_hiba.hh"
athos@36: //#include <marci_list_graph.hh>
athos@36: #include <marci_graph_traits.hh>
athos@36: #include "reverse_bfs.hh"
athos@36: 
athos@36: using namespace std;
athos@36: 
athos@36: namespace marci {
athos@36: 
athos@36:   template <typename graph_type, typename T>
athos@36:   class preflow_push {
athos@36: 
athos@36:     //Hasznos typedef-ek
athos@36:     typedef graph_traits<graph_type>::node_iterator node_iterator;
athos@36:     typedef graph_traits<graph_type>::edge_iterator edge_iterator;
athos@36:     typedef graph_traits<graph_type>::each_node_iterator each_node_iterator;
athos@36:     typedef graph_traits<graph_type>::each_edge_iterator each_edge_iterator;
athos@36:     typedef graph_traits<graph_type>::out_edge_iterator out_edge_iterator;
athos@36:     typedef graph_traits<graph_type>::in_edge_iterator in_edge_iterator;
athos@36:     typedef graph_traits<graph_type>::sym_edge_iterator sym_edge_iterator;
athos@36: 
athos@36:     //---------------------------------------------
athos@36:     //Parameters of the algorithm
athos@36:     //---------------------------------------------
athos@36:     //Fully examine an active node until excess becomes 0
athos@36:     enum node_examination_t {examine_full, examine_to_relabel};
athos@36:     //No more implemented yet:, examine_only_one_edge};
athos@36:     node_examination_t node_examination;
athos@36:     //Which implementation to be used
athos@36:     enum implementation_t {impl_fifo, impl_highest_label};
athos@36:     //No more implemented yet:};
athos@36:     implementation_t implementation;
athos@36:     //---------------------------------------------
athos@36:     //Parameters of the algorithm
athos@36:     //---------------------------------------------
athos@36:  
athos@36:   private:
athos@36:     //input
athos@36:     graph_type& G;
athos@36:     node_iterator s;
athos@36:     node_iterator t;
athos@36:     edge_property_vector<graph_type, T> &capacity;
athos@36:     //output
athos@36:     edge_property_vector<graph_type, T> preflow;
athos@36:     T maxflow_value;
athos@36:   
athos@36:     //auxiliary variables for computation
athos@36:     int number_of_nodes;
athos@36:     node_property_vector<graph_type, int> level;
athos@36:     node_property_vector<graph_type, T> excess;
athos@36:     
athos@36:     //Number of nodes on each level
athos@36:     vector<int> num_of_nodes_on_level;
athos@36:     
athos@36:     //For the FIFO implementation
athos@36:     list<node_iterator> fifo_nodes;
athos@36:     //For 'highest label' implementation
athos@36:     int highest_active;
athos@36:     //int second_highest_active;
athos@36:     vector< list<node_iterator> > active_nodes;
athos@36: 
athos@36:   public:
athos@36:   
athos@36:     //Constructing the object using the graph, source, sink and capacity vector
athos@36:     preflow_push(
athos@36: 		      graph_type& _G, 
athos@36: 		      node_iterator _s, 
athos@36: 		      node_iterator _t, 
athos@36: 		      edge_property_vector<graph_type, T>& _capacity)
athos@36:       : G(_G), s(_s), t(_t), 
athos@36: 	capacity(_capacity), 
athos@36: 	preflow(_G),
athos@36: 	//Counting the number of nodes
athos@36: 	number_of_nodes(number_of(G.first_node())),
athos@36: 	level(_G),
athos@36: 	excess(_G)//,
athos@36:         // Default constructor: active_nodes()
athos@36:     { 
athos@36:       //Simplest parameter settings
athos@36:       node_examination = examine_full;//examine_to_relabel;//
athos@36:       //Which implementation to be usedexamine_full
athos@36:       implementation = impl_highest_label;//impl_fifo;
athos@36:  
athos@36:       //
athos@36:       num_of_nodes_on_level.resize(2*number_of_nodes-1);
athos@36:       num_of_nodes_on_level.clear();
athos@36: 
athos@36:       switch(implementation){
athos@36:       case impl_highest_label :{
athos@36: 	active_nodes.resize(2*number_of_nodes-1);
athos@36: 	active_nodes.clear();
athos@36: 	break;
athos@36:       }
athos@36:       default:
athos@36: 	break;
athos@36:       }
athos@36: 
athos@36:     }
athos@36: 
athos@36:     //Returns the value of a maximal flow 
athos@36:     T run();
athos@36:   
athos@36:     edge_property_vector<graph_type, T> getmaxflow(){
athos@36:       return preflow;
athos@36:     }
athos@36: 
athos@36: 
athos@36:   private:
athos@36:     //For testing purposes only
athos@36:     //Lists the node_properties
athos@36:     void write_property_vector(node_property_vector<graph_type, T> a, 
athos@36: 			       char* prop_name="property"){
athos@36:       for(each_node_iterator i=G.first_node(); i.valid(); ++i) {
athos@36: 	cout<<"Node id.: "<<G.id(i)<<", "<<prop_name<<" value: "<<a.get(i)<<endl;
athos@36:       }
athos@36:       cout<<endl;
athos@36:     }
athos@36: 
athos@36:     //Modifies the excess of the node and makes sufficient changes
athos@36:     void modify_excess(const node_iterator& a ,T v){
athos@36: 	T old_value=excess.get(a);
athos@36: 	excess.put(a,old_value+v);
athos@36:     }
athos@36:   
athos@36:     //This private procedure is supposed to modify the preflow on edge j
athos@36:     //by value v (which can be positive or negative as well) 
athos@36:     //and maintain the excess on the head and tail
athos@36:     //Here we do not check whether this is possible or not
athos@36:     void modify_preflow(edge_iterator j, const T& v){
athos@36: 
athos@36:       //Auxiliary variable
athos@36:       T old_value;
athos@36: 	
athos@36:       //Modifiyng the edge
athos@36:       old_value=preflow.get(j);
athos@36:       preflow.put(j,old_value+v);
athos@36: 
athos@36: 
athos@36:       //Modifiyng the head
athos@36:       modify_excess(G.head(j),v);
athos@36: 	
athos@36:       //Modifiyng the tail
athos@36:       modify_excess(G.tail(j),-v);
athos@36: 
athos@36:     }
athos@36: 
athos@36:     //Gives the active node to work with 
athos@36:     //(depending on the implementation to be used)
athos@36:     node_iterator get_active_node(){
athos@36:       //cout<<highest_active<<endl;
athos@36: 
athos@36:       switch(implementation) {
athos@36:       case impl_highest_label : {
athos@36: 
athos@36: 	//First need to find the highest label for which there"s an active node
athos@36: 	while( highest_active>=0 && active_nodes[highest_active].empty() ){ 
athos@36: 	  --highest_active;
athos@36: 	}
athos@36: 
athos@36: 	if( highest_active>=0) {
athos@36: 	  node_iterator a=active_nodes[highest_active].front();
athos@36: 	  active_nodes[highest_active].pop_front();
athos@36: 	  return a;
athos@36: 	}
athos@36: 	else {
athos@36: 	  return node_iterator();
athos@36: 	}
athos@36: 	
athos@36: 	break;
athos@36: 	
athos@36:       }
athos@36:       case impl_fifo : {
athos@36: 
athos@36: 	if( ! fifo_nodes.empty() ) {
athos@36: 	  node_iterator a=fifo_nodes.front();
athos@36: 	  fifo_nodes.pop_front();
athos@36: 	  return a;
athos@36: 	}
athos@36: 	else {
athos@36: 	  return node_iterator();
athos@36: 	}
athos@36: 	break;
athos@36:       }
athos@36:       }
athos@36:       //
athos@36:       return node_iterator();
athos@36:     }
athos@36: 
athos@36:     //Puts node 'a' among the active nodes
athos@36:     void make_active(const node_iterator& a){
athos@36:       //s and t never become active
athos@36:       if (a!=s && a!= t){
athos@36: 	switch(implementation){
athos@36: 	case impl_highest_label :
athos@36: 	  active_nodes[level.get(a)].push_back(a);
athos@36: 	  break;
athos@36: 	case impl_fifo :
athos@36: 	  fifo_nodes.push_back(a);
athos@36: 	  break;
athos@36: 	}
athos@36: 
athos@36:       }
athos@36: 
athos@36:       //Update highest_active label
athos@36:       if (highest_active<level.get(a)){
athos@36: 	highest_active=level.get(a);
athos@36:       }
athos@36: 
athos@36:     }
athos@36: 
athos@36:     //Changes the level of node a and make sufficent changes
athos@36:     void change_level_to(node_iterator a, int new_value){
athos@36:       int seged = level.get(a);
athos@36:       level.put(a,new_value);
athos@36:       --num_of_nodes_on_level[seged];
athos@36:       ++num_of_nodes_on_level[new_value];
athos@36:     }
athos@36: 
athos@36:     //Collection of things useful (or necessary) to do before running
athos@36:     void preprocess(){
athos@36: 
athos@36:       //---------------------------------------
athos@36:       //Initialize parameters
athos@36:       //---------------------------------------
athos@36: 
athos@36:       //Setting starting preflow, level and excess values to zero
athos@36:       //This can be important, if the algorithm is run more then once
athos@36:       for(each_node_iterator i=G.first_node(); i.valid(); ++i) {
athos@36:         level.put(i,0);
athos@36:         excess.put(i,0);
athos@36: 	for(out_edge_iterator j=G.first_out_edge(i); j.valid(); ++j) 
athos@36: 	  preflow.put(j, 0);
athos@36:       }
athos@36:       num_of_nodes_on_level[0]=number_of_nodes;
athos@36:       highest_active=0;
athos@36:       //---------------------------------------
athos@36:       //Initialize parameters
athos@36:       //---------------------------------------
athos@36: 
athos@36:       
athos@36:       //------------------------------------
athos@36:       //This is the only part that uses BFS
athos@36:       //------------------------------------
athos@36:       //Setting starting level values using reverse bfs
athos@36:       reverse_bfs<graph_type> rev_bfs(G,t);
athos@36:       rev_bfs.run();
athos@36:       //write_property_vector(rev_bfs.dist,"rev_bfs");
athos@36:       for(each_node_iterator i=G.first_node(); i.valid(); ++i) {
athos@36:         change_level_to(i,rev_bfs.dist(i));
athos@36: 	//level.put(i,rev_bfs.dist.get(i));
athos@36:       }
athos@36:       //------------------------------------
athos@36:       //This is the only part that uses BFS
athos@36:       //------------------------------------
athos@36:       
athos@36:       
athos@36:       //Starting level of s
athos@36:       change_level_to(s,number_of_nodes);
athos@36:       //level.put(s,number_of_nodes);
athos@36:       
athos@36:       
athos@36:       //we push as much preflow from s as possible to start with
athos@36:       for(out_edge_iterator j=G.first_out_edge(s); j.valid(); ++j){ 
athos@36: 	modify_preflow(j,capacity.get(j) );
athos@36: 	make_active(G.head(j));
athos@36: 	int lev=level.get(G.head(j));
athos@36: 	if(highest_active<lev){
athos@36: 	  highest_active=lev;
athos@36: 	}
athos@36:       }
athos@36:       //cout<<highest_active<<endl;
athos@36:     } 
athos@36: 
athos@36:     
athos@36:     //If the preflow is less than the capacity on the given edge
athos@36:     //then it is an edge in the residual graph
athos@36:     bool is_admissible_forward_edge(out_edge_iterator j, int& new_level){
athos@36:       if (capacity.get(j)>preflow.get(j)){
athos@36: 	if(level.get(G.tail(j))==level.get(G.head(j))+1){
athos@36: 	  return true;
athos@36: 	}
athos@36: 	else{
athos@36: 	  if (level.get(G.head(j)) < new_level)
athos@36: 	    new_level=level.get(G.head(j));
athos@36: 	}
athos@36:       }
athos@36:       return false;
athos@36:     }
athos@36: 
athos@36:     //If the preflow is greater than 0 on the given edge
athos@36:     //then the edge reversd is an edge in the residual graph
athos@36:     bool is_admissible_backward_edge(in_edge_iterator j, int& new_level){
athos@36:       if (0<preflow.get(j)){
athos@36: 	if(level.get(G.tail(j))==level.get(G.head(j))-1){
athos@36: 	  return true;
athos@36: 	}
athos@36: 	else{
athos@36: 	  if (level.get(G.tail(j)) < new_level)
athos@36: 	    new_level=level.get(G.tail(j));
athos@36: 	}
athos@36: 	
athos@36:       }
athos@36:       return false;
athos@36:     }
athos@36: 
athos@36:  
athos@36:   };  //class preflow_push  
athos@36: 
athos@36:   template<typename graph_type, typename T>
athos@36:     T preflow_push<graph_type, T>::run() {
athos@36:     
athos@36:     preprocess();
athos@36:     
athos@36:     T e,v;
athos@36:     node_iterator a;
athos@36:     while (a=get_active_node(), a.valid()){
athos@36:       //cout<<G.id(a)<<endl;
athos@36:       //write_property_vector(excess,"excess");
athos@36:       //write_property_vector(level,"level");
athos@36: 
athos@36:       //Initial value for the new level for the active node we are dealing with
athos@36:       int new_level=2*number_of_nodes;
athos@36: 
athos@36:       bool go_to_next_node=false;
athos@36:       e = excess.get(a);
athos@36:       while (!go_to_next_node){
athos@36: 	
athos@36: 	//Out edges from node a
athos@36: 	{
athos@36: 	  out_edge_iterator j=G.first_out_edge(a);
athos@36: 	  while (j.valid() && e){
athos@36: 
athos@36: 	    if (is_admissible_forward_edge(j,new_level)){
athos@36: 	      v=min(e,capacity.get(j) - preflow.get(j));
athos@36: 	      e -= v;
athos@36: 	      //New node might become active
athos@36: 	      if (excess.get(G.head(j))==0){
athos@36: 		make_active(G.head(j));
athos@36: 	      }
athos@36: 	      modify_preflow(j,v);
athos@36: 	    }
athos@36: 	    ++j;
athos@36: 	  }
athos@36: 	}
athos@36: 	//In edges to node a
athos@36: 	{
athos@36: 	  in_edge_iterator j=G.first_in_edge(a);
athos@36: 	  while (j.valid() && e){
athos@36: 	    if (is_admissible_backward_edge(j,new_level)){
athos@36: 	      v=min(e,preflow.get(j));
athos@36: 	      e -= v;
athos@36: 	      //New node might become active
athos@36: 	      if (excess.get(G.tail(j))==0){
athos@36: 		make_active(G.tail(j));
athos@36: 	      }
athos@36: 	      modify_preflow(j,-v);
athos@36: 	    }
athos@36: 	    ++j;
athos@36: 	  }
athos@36: 	}
athos@36: 
athos@36: 	//cout<<G.id(a)<<" "<<new_level<<endl;
athos@36: 
athos@36: 	if (0==e){
athos@36: 	  //Saturating push
athos@36: 	  go_to_next_node=true;
athos@36: 	}
athos@36: 	else{//If there is still excess in node a
athos@36: 
athos@36: 	  //Level remains empty
athos@36: 	  if (num_of_nodes_on_level[level.get(a)]==1){
athos@36: 	    change_level_to(a,number_of_nodes);
athos@36: 	    //go_to_next_node=True;
athos@36: 	  }
athos@36: 	  else{
athos@36: 	    change_level_to(a,new_level+1);
athos@36: 	    //increase_level(a);
athos@36: 	  }
athos@36: 
athos@36:     
athos@36: 	  
athos@36: 
athos@36: 	  switch(node_examination){
athos@36: 	  case examine_to_relabel:
athos@36: 	    make_active(a);
athos@36: 
athos@36: 	    go_to_next_node = true;
athos@36: 	    break;
athos@36: 	  default:
athos@36: 	    break;
athos@36: 	  }
athos@36: 	  
athos@36:     
athos@36: 	
athos@36: 	}//if (0==e)
athos@36:       }
athos@36:     }
athos@36:     maxflow_value = excess.get(t);
athos@36:     return maxflow_value;
athos@36:   }//run
athos@36: 
athos@36: 
athos@36: }//namespace marci
athos@36: 
athos@36: #endif //PREFLOW_PUSH_HH