src/work/marci_max_flow.hh
author jacint
Fri, 23 Jan 2004 22:22:12 +0000
changeset 32 82f6987d6d2e
parent 17 8b29d935f1a6
child 107 8d62f0072ff0
permissions -rw-r--r--
A new version is coming.
     1 #ifndef MARCI_MAX_FLOW_HH
     2 #define MARCI_MAX_FLOW_HH
     3 
     4 #include <algorithm>
     5 
     6 #include <marci_property_vector.hh>
     7 #include <marci_bfs.hh>
     8 
     9 namespace marci {
    10 
    11   template<typename graph_type, typename T>
    12   class res_graph_type { 
    13     typedef typename graph_type::node_iterator node_iterator;
    14     typedef typename graph_type::each_node_iterator each_node_iterator;
    15     typedef typename graph_type::sym_edge_iterator old_sym_edge_iterator;
    16     graph_type& G;
    17     edge_property_vector<graph_type, T>& flow;
    18     edge_property_vector<graph_type, T>& capacity;
    19   public:
    20     res_graph_type(graph_type& _G, edge_property_vector<graph_type, T>& _flow, edge_property_vector<graph_type, T>& _capacity) : G(_G), flow(_flow), capacity(_capacity) { }
    21 
    22     class edge_iterator {
    23       friend class res_graph_type<graph_type, T>;
    24     protected:
    25       res_graph_type<graph_type, T>* resG;
    26       old_sym_edge_iterator sym;
    27     public:
    28       edge_iterator() { }
    29       //bool is_free() {  
    30       //if (resG->G.a_node(sym)==resG->G.tail(sym)) { 
    31       //  return (resG->flow.get(sym)<resG->capacity.get(sym)); 
    32       //} else { 
    33       //  return (resG->flow.get(sym)>0); 
    34       //}
    35       //}
    36       T free() { 
    37 	if (resG->G.a_node(sym)==resG->G.tail(sym)) { 
    38 	  return (resG->capacity.get(sym)-resG->flow.get(sym)); 
    39 	} else { 
    40 	  return (resG->flow.get(sym)); 
    41 	}
    42       }
    43       bool valid() { return sym.valid(); }
    44       void make_invalid() { sym.make_invalid(); }
    45       void augment(T a) {
    46 	if (resG->G.a_node(sym)==resG->G.tail(sym)) { 
    47 	  resG->flow.put(sym, resG->flow.get(sym)+a);
    48 	} else { 
    49 	  resG->flow.put(sym, resG->flow.get(sym)-a);
    50 	}
    51       }
    52     };
    53 
    54     class out_edge_iterator : public edge_iterator {
    55     public:
    56       out_edge_iterator() { }
    57       out_edge_iterator(res_graph_type<graph_type, T>& _resG, const node_iterator& v) { 
    58       	resG=&_resG;
    59 	sym=resG->G.first_sym_edge(v);
    60 	while( sym.valid() && !(free()>0) ) { ++sym; }
    61       }
    62       out_edge_iterator& operator++() { 
    63 	++sym; 
    64 	while( sym.valid() && !(free()>0) ) { ++sym; }
    65 	return *this; 
    66       }
    67     };
    68 
    69     out_edge_iterator first_out_edge(const node_iterator& v) {
    70       return out_edge_iterator(*this, v);
    71     }
    72 
    73     each_node_iterator first_node() {
    74       return G.first_node();
    75     }
    76 
    77     node_iterator tail(const edge_iterator& e) { return G.a_node(e.sym); }
    78     node_iterator head(const edge_iterator& e) { return G.b_node(e.sym); }
    79 
    80     int id(const node_iterator& v) { return G.id(v); }
    81 
    82     //node_iterator invalid_node() { return G.invalid_node(); }
    83     //res_edge_it invalid_edge() { res_edge_it n; n.sym=G.invalid_sym_edge(); return n; } 
    84   };
    85 
    86   template <typename graph_type, typename T>
    87   struct max_flow_type {
    88     typedef typename graph_type::node_iterator node_iterator;
    89     typedef typename graph_type::edge_iterator edge_iterator;
    90     typedef typename graph_type::each_node_iterator each_node_iterator;
    91     typedef typename graph_type::out_edge_iterator out_edge_iterator;
    92     typedef typename graph_type::in_edge_iterator in_edge_iterator;
    93     graph_type& G;
    94     node_iterator s;
    95     node_iterator t;
    96     edge_property_vector<graph_type, T> flow;
    97     edge_property_vector<graph_type, T>& capacity;
    98 
    99     max_flow_type(graph_type& _G, node_iterator _s, node_iterator _t, edge_property_vector<graph_type, T>& _capacity) : G(_G), s(_s), t(_t), flow(_G), capacity(_capacity) { 
   100       for(each_node_iterator i=G.first_node(); i.valid(); ++i) 
   101 	for(out_edge_iterator j=G.first_out_edge(i); j.valid(); ++j) 
   102 	  flow.put(j, 0);
   103     }
   104     void run() {
   105       typedef res_graph_type<graph_type, T> aug_graph_type;
   106       aug_graph_type res_graph(G, flow, capacity);
   107 
   108       bool augment;
   109       do {
   110 	augment=false;
   111 
   112 	typedef std::queue<aug_graph_type::out_edge_iterator> bfs_queue_type;
   113 	bfs_queue_type bfs_queue;
   114 	bfs_queue.push(res_graph.first_out_edge(s));
   115 
   116 	typedef node_property_vector<aug_graph_type, bool> reached_type;
   117 	reached_type reached(res_graph, false);
   118 	reached.put(s, true); 
   119 	
   120 	bfs_iterator1< aug_graph_type, reached_type > 
   121 	res_bfs(res_graph, bfs_queue, reached);
   122 
   123 	typedef node_property_vector<aug_graph_type, aug_graph_type::edge_iterator> pred_type;
   124 	pred_type pred(res_graph);
   125 	aug_graph_type::edge_iterator a; 
   126 	a.make_invalid();
   127 	pred.put(s, a);
   128 
   129 	typedef node_property_vector<aug_graph_type, int> free_type;
   130 	free_type free(res_graph);
   131 	
   132 	//searching for augmenting path
   133 	while ( res_bfs.valid() ) { 
   134 	  //std::cout<<"KULSO ciklus itt jar: "<<G.id(res_graph.tail(res_bfs))<<"->"<<G.id(res_graph.head(res_bfs))<<std::endl;
   135 	  if (res_bfs.newly_reached()) {
   136 	    aug_graph_type::edge_iterator e;
   137 	    e=res_bfs;
   138 	    node_iterator v=res_graph.tail(e);
   139 	    node_iterator w=res_graph.head(e);
   140 	    //std::cout<<G.id(v)<<"->"<<G.id(w)<<", "<<G.id(w)<<" is newly reached";
   141 	    pred.put(w, e);
   142 	    if (pred.get(v).valid()) {
   143 	      free.put(w, std::min(free.get(v), e.free()));
   144 	      //std::cout <<" nem elso csucs: ";
   145 	      //std::cout <<"szabad kap eddig: "<< free.get(w) << " ";
   146 	    } else {
   147 	      free.put(w, e.free()); 
   148 	      //std::cout <<" elso csucs: ";
   149 	      //std::cout <<"szabad kap eddig: "<< free.get(w) << " ";
   150 	    }
   151 	    //std::cout<<std::endl;
   152 	  }
   153 	
   154 	  if (res_graph.head(res_bfs)==t) break;
   155 	  ++res_bfs;
   156 	}
   157 	if (reached.get(t)) {
   158 	  augment=true;
   159 	  node_iterator n=t;
   160 	  T augment_value=free.get(t);
   161 	  std::cout<<"augmentation: ";
   162 	  while (pred.get(n).valid()) { 
   163 	    aug_graph_type::edge_iterator e=pred.get(n);
   164 	    e.augment(augment_value); 
   165 	    std::cout<<"("<<res_graph.tail(e)<< "->"<<res_graph.head(e)<<") ";
   166 	    n=res_graph.tail(e);
   167 	  }
   168 	  std::cout<<std::endl;
   169 	}
   170 
   171 	std::cout << "actual flow: "<< std::endl;
   172 	for(typename graph_type::each_edge_iterator e=G.first_edge(); e.valid(); ++e) { 
   173 	  std::cout<<"("<<G.tail(e)<< "-"<<flow.get(e)<<"->"<<G.head(e)<<") ";
   174 	}
   175 	std::cout<<std::endl;
   176 
   177       } while (augment);
   178     }
   179   };
   180 
   181 } // namespace marci
   182 
   183 #endif //MARCI_MAX_FLOW_HH