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Location: LEMON/LEMON-official/test/gomory_hu_test.cc

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deba@inf.elte.hu
Fix critical bug in preflow (#372) The wrong transition between the bound decrease and highest active heuristics caused the bug. The last node chosen in bound decrease mode is used in the first iteration in highest active mode.
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#include <iostream>



#include "test_tools.h"

#include <lemon/smart_graph.h>

#include <lemon/concepts/graph.h>

#include <lemon/concepts/maps.h>

#include <lemon/lgf_reader.h>

#include <lemon/gomory_hu.h>

#include <cstdlib>



using namespace std;

using namespace lemon;



typedef SmartGraph Graph;



char test_lgf[] =

  "@nodes\n"

  "label\n"

  "0\n"

  "1\n"

  "2\n"

  "3\n"

  "4\n"

  "@arcs\n"

  "     label capacity\n"

  "0 1  0     1\n"

  "1 2  1     1\n"

  "2 3  2     1\n"

  "0 3  4     5\n"

  "0 3  5     10\n"

  "0 3  6     7\n"

  "4 2  7     1\n"

  "@attributes\n"

  "source 0\n"

  "target 3\n";

  

void checkGomoryHuCompile()

{

  typedef int Value;

  typedef concepts::Graph Graph;



  typedef Graph::Node Node;

  typedef Graph::Edge Edge;

  typedef concepts::ReadMap<Edge, Value> CapMap;

  typedef concepts::ReadWriteMap<Node, bool> CutMap;



  Graph g;

  Node n;

  CapMap cap;

  CutMap cut;

  Value v;

  int d;



  GomoryHu<Graph, CapMap> gh_test(g, cap);

  const GomoryHu<Graph, CapMap>&

    const_gh_test = gh_test;



  gh_test.run();



  n = const_gh_test.predNode(n);

  v = const_gh_test.predValue(n);

  d = const_gh_test.rootDist(n);

  v = const_gh_test.minCutValue(n, n);

  v = const_gh_test.minCutMap(n, n, cut);

}



GRAPH_TYPEDEFS(Graph);

typedef Graph::EdgeMap<int> IntEdgeMap;

typedef Graph::NodeMap<bool> BoolNodeMap;



int cutValue(const Graph& graph, const BoolNodeMap& cut,

	     const IntEdgeMap& capacity) {



  int sum = 0;

  for (EdgeIt e(graph); e != INVALID; ++e) {

    Node s = graph.u(e);

    Node t = graph.v(e);



    if (cut[s] != cut[t]) {

      sum += capacity[e];

    }

  }

  return sum;

}





int main() {

  Graph graph;

  IntEdgeMap capacity(graph);



  std::istringstream input(test_lgf);

  GraphReader<Graph>(graph, input).

    edgeMap("capacity", capacity).run();



  GomoryHu<Graph> ght(graph, capacity);

  ght.run();



  for (NodeIt u(graph); u != INVALID; ++u) {

    for (NodeIt v(graph); v != u; ++v) {

      Preflow<Graph, IntEdgeMap> pf(graph, capacity, u, v);

      pf.runMinCut();

      BoolNodeMap cm(graph);

      ght.minCutMap(u, v, cm);

      check(pf.flowValue() == ght.minCutValue(u, v), "Wrong cut 1");

      check(cm[u] != cm[v], "Wrong cut 2");

      check(pf.flowValue() == cutValue(graph, cm, capacity), "Wrong cut 3");



      int sum=0;

      for(GomoryHu<Graph>::MinCutEdgeIt a(ght, u, v);a!=INVALID;++a)

        sum+=capacity[a]; 

      check(sum == ght.minCutValue(u, v), "Problem with MinCutEdgeIt");



      sum=0;

      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,true);n!=INVALID;++n)

        sum++;

      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,false);n!=INVALID;++n)

        sum++;

      check(sum == countNodes(graph), "Problem with MinCutNodeIt");

    }

  }

  

  return 0;

}