src/work/jacint/preflow.cc
author marci
Thu, 29 Apr 2004 10:16:46 +0000
changeset 466 cd40ecf4d2a9
child 470 b64956c701c9
permissions -rw-r--r--
preflow, maxflow comp
     1 #include <iostream>
     2 
     3 #include <smart_graph.h>
     4 #include <dimacs.h>
     5 #include <preflow.h>
     6 #include <time_measure.h>
     7 
     8 using namespace hugo;
     9 
    10 int main(int, char **) {
    11  
    12   typedef SmartGraph Graph;
    13   
    14   typedef Graph::Node Node;
    15   typedef Graph::EdgeIt EdgeIt;
    16 
    17   Graph G;
    18   Node s, t;
    19   Graph::EdgeMap<int> cap(G);
    20   readDimacsMaxFlow(std::cin, G, s, t, cap);
    21   Timer ts;
    22   
    23   std::cout <<
    24     "\n  Testing preflow.h on a graph with " << 
    25     G.nodeNum() << " nodes and " << G.edgeNum() << " edges..."
    26 	   << std::endl;
    27 
    28 
    29   Graph::EdgeMap<int> flow(G,0);
    30   Preflow<Graph, int> preflow_test(G, s, t, cap, flow);
    31   std::cout << "\nCalling run() (flow must be constant zero)..."<<std::endl;
    32   ts.reset();
    33   preflow_test.run();
    34   std::cout << "Elapsed time: " << ts << std::endl;
    35 
    36   Graph::NodeMap<bool> mincut(G);
    37   preflow_test.minMinCut(mincut); 
    38   int min_min_cut_value=0;
    39   Graph::NodeMap<bool> cut(G);
    40   preflow_test.minCut(cut); 
    41   int min_cut_value=0;
    42   Graph::NodeMap<bool> maxcut(G);
    43   preflow_test.maxMinCut(maxcut); 
    44   int max_min_cut_value=0;
    45   EdgeIt e;
    46   for(G.first(e); G.valid(e); G.next(e)) {
    47     int c=cap[e];
    48     if (mincut[G.tail(e)] && !mincut[G.head(e)]) min_min_cut_value+=c;
    49     if (cut[G.tail(e)] && !cut[G.head(e)]) min_cut_value+=c; 
    50     if (maxcut[G.tail(e)] && !maxcut[G.head(e)]) max_min_cut_value+=c;
    51   }
    52 
    53   std::cout << "\nChecking the result: " <<std::endl;  
    54   std::cout << "Flow value: "<< preflow_test.flowValue() << std::endl;
    55   std::cout << "Min cut value: "<< min_cut_value << std::endl;
    56   std::cout << "Min min cut value: "<< min_min_cut_value << std::endl;
    57   std::cout << "Max min cut value: "<< max_min_cut_value << 
    58     std::endl;
    59 
    60   if ( preflow_test.flowValue() == min_cut_value &&
    61        min_cut_value == min_min_cut_value &&
    62        min_min_cut_value == max_min_cut_value )
    63     std::cout << "They are equal. " <<std::endl;  
    64 
    65 
    66 
    67 
    68 
    69   Preflow<Graph, int> preflow_test2(G, s, t, cap, flow);
    70   std::cout << "\n\nCalling preflow(GEN_FLOW) with the given maximum flow..."<<std::endl;
    71   ts.reset();
    72   preflow_test2.preflow(preflow_test2.GEN_FLOW);
    73   std::cout << "Elapsed time: " << ts << std::endl;
    74 
    75   Graph::NodeMap<bool> mincut2(G);
    76   preflow_test.minMinCut(mincut2); 
    77   int min_min_cut2_value=0;
    78   Graph::NodeMap<bool> cut2(G);
    79   preflow_test.minCut(cut2); 
    80   int min_cut2_value=0;
    81   Graph::NodeMap<bool> maxcut2(G);
    82   preflow_test.maxMinCut(maxcut2); 
    83   int max_min_cut2_value=0;
    84   for(G.first(e); G.valid(e); G.next(e)) {
    85     int c=cap[e];
    86     if (mincut2[G.tail(e)] && !mincut2[G.head(e)]) min_min_cut2_value+=c;
    87     if (cut2[G.tail(e)] && !cut2[G.head(e)]) min_cut2_value+=c; 
    88     if (maxcut2[G.tail(e)] && !maxcut2[G.head(e)]) max_min_cut2_value+=c;
    89   }
    90 
    91   std::cout << "\nThe given flow value is "
    92 	    << preflow_test2.flowValue();
    93 
    94   if ( preflow_test2.flowValue() == min_cut2_value &&
    95        min_cut2_value == min_min_cut2_value &&
    96        min_min_cut2_value == max_min_cut2_value )
    97     std::cout <<", which is equal to all three min cut values." 
    98 	      <<std::endl;  
    99 
   100 
   101 
   102 
   103 
   104   Graph::EdgeMap<int> flow3(G,0);
   105   Preflow<Graph, int> preflow_test3(G, s, t, cap, flow3);
   106   std::cout << "\n\nCalling preflowPhase0(PREFLOW) on the constant zero flow..."<<std::endl;
   107   ts.reset();
   108   preflow_test3.preflowPhase0(preflow_test3.PREFLOW);
   109   std::cout << "Elapsed time: " << ts << std::endl;
   110   Graph::NodeMap<bool> actcut3(G);
   111   std::cout << "\nCalling actMinCut()..."<<std::endl;
   112   preflow_test3.actMinCut(actcut3); 
   113   std::cout << "Calling preflowPhase1() on the given flow..."<<std::endl;
   114   ts.reset();
   115   preflow_test3.preflowPhase1();
   116   std::cout << "Elapsed time: " << ts << std::endl;
   117   
   118   int act_min_cut3_value=0;
   119   
   120   Graph::NodeMap<bool> mincut3(G);
   121   preflow_test.minMinCut(mincut3); 
   122   int min_min_cut3_value=0;
   123   
   124   Graph::NodeMap<bool> cut3(G);
   125   preflow_test.minCut(cut3); 
   126   int min_cut3_value=0;
   127   
   128   Graph::NodeMap<bool> maxcut3(G);
   129   preflow_test.maxMinCut(maxcut3); 
   130   int max_min_cut3_value=0;
   131   
   132   for(G.first(e); G.valid(e); G.next(e)) {
   133     int c=cap[e];
   134     if (mincut3[G.tail(e)] && !mincut3[G.head(e)]) min_min_cut3_value+=c;
   135     if (cut3[G.tail(e)] && !cut3[G.head(e)]) min_cut3_value+=c; 
   136     if (maxcut3[G.tail(e)] && !maxcut3[G.head(e)]) max_min_cut3_value+=c;
   137     if (actcut3[G.tail(e)] && !actcut3[G.head(e)]) act_min_cut3_value+=c;
   138   }
   139 
   140  std::cout << "\nThe min cut value given by actMinCut() after phase 0 is "<<
   141    act_min_cut3_value;
   142 
   143   if ( preflow_test3.flowValue() == min_cut3_value &&
   144        min_cut3_value == min_min_cut3_value &&
   145        min_min_cut3_value == max_min_cut3_value &&
   146        max_min_cut3_value == act_min_cut3_value ) {
   147     std::cout << 
   148       ", which is equal to the given flow value and to all three min cut values after phase 1." 
   149 	      <<std::endl;  
   150   }
   151 
   152 
   153 
   154 
   155 
   156   Graph::EdgeMap<int> flow4(G,0);
   157   Preflow<Graph, int> preflow_test4(G, s, t, cap, flow4);
   158   std::cout << 
   159     "\n\nCalling preflow(PREFLOW) with the constant 0 flow, the result is f..."
   160 	    <<std::endl;
   161   preflow_test4.preflow(preflow_test4.PREFLOW);
   162 
   163   std::cout << "Swapping the source and the target, "<<std::endl;
   164   std::cout << "by calling resetSource(t) and resetTarget(s)..."
   165 	    <<std::endl;
   166   preflow_test4.resetSource(t);
   167   preflow_test4.resetTarget(s);
   168 
   169   std::cout << 
   170     "Calling preflow(PREFLOW) to find a maximum t-s flow starting with flow f..."
   171 	    <<std::endl;
   172   preflow_test4.preflow(preflow_test4.PREFLOW);
   173 
   174   Graph::NodeMap<bool> mincut4(G);
   175   preflow_test4.minMinCut(mincut4); 
   176   int min_min_cut4_value=0;
   177   Graph::NodeMap<bool> cut4(G);
   178   preflow_test4.minCut(cut4); 
   179   int min_cut4_value=0;
   180   Graph::NodeMap<bool> maxcut4(G);
   181   preflow_test4.maxMinCut(maxcut4); 
   182   int max_min_cut4_value=0;
   183   for(G.first(e); G.valid(e); G.next(e)) {
   184     int c=cap[e];
   185     if (mincut4[G.tail(e)] && !mincut4[G.head(e)]) min_min_cut4_value+=c;
   186     if (cut4[G.tail(e)] && !cut4[G.head(e)]) min_cut4_value+=c; 
   187     if (maxcut4[G.tail(e)] && !maxcut4[G.head(e)]) max_min_cut4_value+=c;
   188   }
   189 
   190   std::cout << "\nThe given flow value is "
   191 	    << preflow_test4.flowValue();
   192   
   193   if ( preflow_test4.flowValue() == min_cut4_value &&
   194        min_cut4_value == min_min_cut4_value &&
   195        min_min_cut4_value == max_min_cut4_value )
   196     std::cout <<", which is equal to all three min cut values." 
   197 	      <<std::endl;  
   198 
   199 
   200 
   201 
   202   Graph::EdgeMap<int> flow5(G,0);
   203   std::cout << "Resetting the stored flow to constant zero, by calling resetFlow..."
   204 	    <<std::endl;
   205   preflow_test4.resetFlow(flow5);
   206   std::cout << 
   207     "Calling preflow(GEN_FLOW) to find a maximum t-s flow "<<std::endl;
   208   std::cout << 
   209     "starting with this constant zero flow..." <<std::endl;
   210   preflow_test4.preflow(preflow_test4.GEN_FLOW);
   211 
   212   Graph::NodeMap<bool> mincut5(G);
   213   preflow_test4.minMinCut(mincut5); 
   214   int min_min_cut5_value=0;
   215   Graph::NodeMap<bool> cut5(G);
   216   preflow_test4.minCut(cut5); 
   217   int min_cut5_value=0;
   218   Graph::NodeMap<bool> maxcut5(G);
   219   preflow_test4.maxMinCut(maxcut5); 
   220   int max_min_cut5_value=0;
   221   for(G.first(e); G.valid(e); G.next(e)) {
   222     int c=cap[e];
   223     if (mincut5[G.tail(e)] && !mincut5[G.head(e)]) min_min_cut5_value+=c;
   224     if (cut5[G.tail(e)] && !cut5[G.head(e)]) min_cut5_value+=c; 
   225     if (maxcut5[G.tail(e)] && !maxcut5[G.head(e)]) max_min_cut5_value+=c;
   226   }
   227 
   228   std::cout << "\nThe given flow value is "
   229 	    << preflow_test4.flowValue();
   230   
   231   if ( preflow_test4.flowValue() == min_cut5_value &&
   232        min_cut5_value == min_min_cut5_value &&
   233        min_min_cut5_value == max_min_cut5_value )
   234     std::cout <<", which is equal to all three min cut values." 
   235 	      <<std::endl<<std::endl;  
   236 
   237 
   238   return 0;
   239 }