COIN-OR::LEMON - Graph Library

source: lemon-1.2/test/gomory_hu_test.cc @ 619:ec817dfc2cb7

Last change on this file since 619:ec817dfc2cb7 was 596:293551ad254f, checked in by Peter Kovacs <kpeter@…>, 11 years ago

Improvements and fixes for the minimum cut algorithms (#264)

File size: 2.7 KB
Line 
1#include <iostream>
2
3#include "test_tools.h"
4#include <lemon/smart_graph.h>
5#include <lemon/concepts/graph.h>
6#include <lemon/concepts/maps.h>
7#include <lemon/lgf_reader.h>
8#include <lemon/gomory_hu.h>
9#include <cstdlib>
10
11using namespace std;
12using namespace lemon;
13
14typedef SmartGraph Graph;
15
16char test_lgf[] =
17  "@nodes\n"
18  "label\n"
19  "0\n"
20  "1\n"
21  "2\n"
22  "3\n"
23  "4\n"
24  "@arcs\n"
25  "     label capacity\n"
26  "0 1  0     1\n"
27  "1 2  1     1\n"
28  "2 3  2     1\n"
29  "0 3  4     5\n"
30  "0 3  5     10\n"
31  "0 3  6     7\n"
32  "4 2  7     1\n"
33  "@attributes\n"
34  "source 0\n"
35  "target 3\n";
36 
37void checkGomoryHuCompile()
38{
39  typedef int Value;
40  typedef concepts::Graph Graph;
41
42  typedef Graph::Node Node;
43  typedef Graph::Edge Edge;
44  typedef concepts::ReadMap<Edge, Value> CapMap;
45  typedef concepts::ReadWriteMap<Node, bool> CutMap;
46
47  Graph g;
48  Node n;
49  CapMap cap;
50  CutMap cut;
51  Value v;
52  int d;
53
54  GomoryHu<Graph, CapMap> gh_test(g, cap);
55  const GomoryHu<Graph, CapMap>&
56    const_gh_test = gh_test;
57
58  gh_test.run();
59
60  n = const_gh_test.predNode(n);
61  v = const_gh_test.predValue(n);
62  d = const_gh_test.rootDist(n);
63  v = const_gh_test.minCutValue(n, n);
64  v = const_gh_test.minCutMap(n, n, cut);
65}
66
67GRAPH_TYPEDEFS(Graph);
68typedef Graph::EdgeMap<int> IntEdgeMap;
69typedef Graph::NodeMap<bool> BoolNodeMap;
70
71int cutValue(const Graph& graph, const BoolNodeMap& cut,
72             const IntEdgeMap& capacity) {
73
74  int sum = 0;
75  for (EdgeIt e(graph); e != INVALID; ++e) {
76    Node s = graph.u(e);
77    Node t = graph.v(e);
78
79    if (cut[s] != cut[t]) {
80      sum += capacity[e];
81    }
82  }
83  return sum;
84}
85
86
87int main() {
88  Graph graph;
89  IntEdgeMap capacity(graph);
90
91  std::istringstream input(test_lgf);
92  GraphReader<Graph>(graph, input).
93    edgeMap("capacity", capacity).run();
94
95  GomoryHu<Graph> ght(graph, capacity);
96  ght.run();
97
98  for (NodeIt u(graph); u != INVALID; ++u) {
99    for (NodeIt v(graph); v != u; ++v) {
100      Preflow<Graph, IntEdgeMap> pf(graph, capacity, u, v);
101      pf.runMinCut();
102      BoolNodeMap cm(graph);
103      ght.minCutMap(u, v, cm);
104      check(pf.flowValue() == ght.minCutValue(u, v), "Wrong cut 1");
105      check(cm[u] != cm[v], "Wrong cut 2");
106      check(pf.flowValue() == cutValue(graph, cm, capacity), "Wrong cut 3");
107
108      int sum=0;
109      for(GomoryHu<Graph>::MinCutEdgeIt a(ght, u, v);a!=INVALID;++a)
110        sum+=capacity[a];
111      check(sum == ght.minCutValue(u, v), "Problem with MinCutEdgeIt");
112
113      sum=0;
114      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,true);n!=INVALID;++n)
115        sum++;
116      for(GomoryHu<Graph>::MinCutNodeIt n(ght, u, v,false);n!=INVALID;++n)
117        sum++;
118      check(sum == countNodes(graph), "Problem with MinCutNodeIt");
119    }
120  }
121 
122  return 0;
123}
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