test/gomory_hu_test.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Fri, 08 Sep 2017 17:02:03 +0200
changeset 1156 f37f0845cf32
parent 545 e72bacfea6b7
child 596 293551ad254f
permissions -rw-r--r--
Bug fix in DIMACS reader (#607)
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#include <iostream>
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#include "test_tools.h"
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#include <lemon/smart_graph.h>
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#include <lemon/lgf_reader.h>
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#include <lemon/gomory_hu.h>
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#include <cstdlib>
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using namespace std;
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using namespace lemon;
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typedef SmartGraph Graph;
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char test_lgf[] =
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  "@nodes\n"
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  "label\n"
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  "0\n"
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  "1\n"
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  "2\n"
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  "3\n"
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  "4\n"
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  "@arcs\n"
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  "     label capacity\n"
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  "0 1  0     1\n"
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  "1 2  1     1\n"
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  "2 3  2     1\n"
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  "0 3  4     5\n"
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  "0 3  5     10\n"
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  "0 3  6     7\n"
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  "4 2  7     1\n"
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  "@attributes\n"
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  "source 0\n"
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  "target 3\n";
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GRAPH_TYPEDEFS(Graph);
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typedef Graph::EdgeMap<int> IntEdgeMap;
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typedef Graph::NodeMap<bool> BoolNodeMap;
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int cutValue(const Graph& graph, const BoolNodeMap& cut,
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	     const IntEdgeMap& capacity) {
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  int sum = 0;
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  for (EdgeIt e(graph); e != INVALID; ++e) {
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    Node s = graph.u(e);
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    Node t = graph.v(e);
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    if (cut[s] != cut[t]) {
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      sum += capacity[e];
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    }
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  }
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  return sum;
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}
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int main() {
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  Graph graph;
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  IntEdgeMap capacity(graph);
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  std::istringstream input(test_lgf);
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  GraphReader<Graph>(graph, input).
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    edgeMap("capacity", capacity).run();
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  GomoryHu<Graph> ght(graph, capacity);
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  ght.run();
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  for (NodeIt u(graph); u != INVALID; ++u) {
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    for (NodeIt v(graph); v != u; ++v) {
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      Preflow<Graph, IntEdgeMap> pf(graph, capacity, u, v);
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      pf.runMinCut();
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      BoolNodeMap cm(graph);
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      ght.minCutMap(u, v, cm);
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      check(pf.flowValue() == ght.minCutValue(u, v), "Wrong cut 1");
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      check(cm[u] != cm[v], "Wrong cut 3");
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      check(pf.flowValue() == cutValue(graph, cm, capacity), "Wrong cut 2");
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      int sum=0;
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      for(GomoryHu<Graph>::MinCutEdgeIt a(ght, u, v);a!=INVALID;++a)
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        sum+=capacity[a]; 
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      check(sum == ght.minCutValue(u, v), "Problem with MinCutEdgeIt");
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      sum=0;
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      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,true);n!=INVALID;++n)
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        sum++;
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      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,false);n!=INVALID;++n)
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        sum++;
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      check(sum == countNodes(graph), "Problem with MinCutNodeIt");
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    }
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  }
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  return 0;
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}