COIN-OR::LEMON - Graph Library

source: lemon-1.2/test/preflow_test.cc @ 783:ef88c0a30f85

Last change on this file since 783:ef88c0a30f85 was 689:86c49553fea5, checked in by Peter Kovacs <kpeter@…>, 10 years ago

Test file + doc improvements (#307)

File size: 6.0 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2009
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#include <iostream>
20
21#include "test_tools.h"
22#include <lemon/smart_graph.h>
23#include <lemon/preflow.h>
24#include <lemon/concepts/digraph.h>
25#include <lemon/concepts/maps.h>
26#include <lemon/lgf_reader.h>
27#include <lemon/elevator.h>
28
29using namespace lemon;
30
31char test_lgf[] =
32  "@nodes\n"
33  "label\n"
34  "0\n"
35  "1\n"
36  "2\n"
37  "3\n"
38  "4\n"
39  "5\n"
40  "6\n"
41  "7\n"
42  "8\n"
43  "9\n"
44  "@arcs\n"
45  "    label capacity\n"
46  "0 1 0     20\n"
47  "0 2 1     0\n"
48  "1 1 2     3\n"
49  "1 2 3     8\n"
50  "1 3 4     8\n"
51  "2 5 5     5\n"
52  "3 2 6     5\n"
53  "3 5 7     5\n"
54  "3 6 8     5\n"
55  "4 3 9     3\n"
56  "5 7 10    3\n"
57  "5 6 11    10\n"
58  "5 8 12    10\n"
59  "6 8 13    8\n"
60  "8 9 14    20\n"
61  "8 1 15    5\n"
62  "9 5 16    5\n"
63  "@attributes\n"
64  "source 1\n"
65  "target 8\n";
66
67void checkPreflowCompile()
68{
69  typedef int VType;
70  typedef concepts::Digraph Digraph;
71
72  typedef Digraph::Node Node;
73  typedef Digraph::Arc Arc;
74  typedef concepts::ReadMap<Arc,VType> CapMap;
75  typedef concepts::ReadWriteMap<Arc,VType> FlowMap;
76  typedef concepts::WriteMap<Node,bool> CutMap;
77
78  typedef Elevator<Digraph, Digraph::Node> Elev;
79  typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;
80
81  Digraph g;
82  Node n;
83  Arc e;
84  CapMap cap;
85  FlowMap flow;
86  CutMap cut;
87  VType v;
88  bool b;
89
90  typedef Preflow<Digraph, CapMap>
91            ::SetFlowMap<FlowMap>
92            ::SetElevator<Elev>
93            ::SetStandardElevator<LinkedElev>
94            ::Create PreflowType;
95  PreflowType preflow_test(g, cap, n, n);
96  const PreflowType& const_preflow_test = preflow_test;
97 
98  const PreflowType::Elevator& elev = const_preflow_test.elevator();
99  preflow_test.elevator(const_cast<PreflowType::Elevator&>(elev));
100  PreflowType::Tolerance tol = const_preflow_test.tolerance();
101  preflow_test.tolerance(tol);
102
103  preflow_test
104    .capacityMap(cap)
105    .flowMap(flow)
106    .source(n)
107    .target(n);
108
109  preflow_test.init();
110  preflow_test.init(cap);
111  preflow_test.startFirstPhase();
112  preflow_test.startSecondPhase();
113  preflow_test.run();
114  preflow_test.runMinCut();
115
116  v = const_preflow_test.flowValue();
117  v = const_preflow_test.flow(e);
118  const FlowMap& fm = const_preflow_test.flowMap();
119  b = const_preflow_test.minCut(n);
120  const_preflow_test.minCutMap(cut);
121 
122  ignore_unused_variable_warning(fm);
123}
124
125int cutValue (const SmartDigraph& g,
126              const SmartDigraph::NodeMap<bool>& cut,
127              const SmartDigraph::ArcMap<int>& cap) {
128
129  int c=0;
130  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
131    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
132  }
133  return c;
134}
135
136bool checkFlow(const SmartDigraph& g,
137               const SmartDigraph::ArcMap<int>& flow,
138               const SmartDigraph::ArcMap<int>& cap,
139               SmartDigraph::Node s, SmartDigraph::Node t) {
140
141  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
142    if (flow[e] < 0 || flow[e] > cap[e]) return false;
143  }
144
145  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
146    if (n == s || n == t) continue;
147    int sum = 0;
148    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
149      sum += flow[e];
150    }
151    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
152      sum -= flow[e];
153    }
154    if (sum != 0) return false;
155  }
156  return true;
157}
158
159int main() {
160
161  typedef SmartDigraph Digraph;
162
163  typedef Digraph::Node Node;
164  typedef Digraph::NodeIt NodeIt;
165  typedef Digraph::ArcIt ArcIt;
166  typedef Digraph::ArcMap<int> CapMap;
167  typedef Digraph::ArcMap<int> FlowMap;
168  typedef Digraph::NodeMap<bool> CutMap;
169
170  typedef Preflow<Digraph, CapMap> PType;
171
172  Digraph g;
173  Node s, t;
174  CapMap cap(g);
175  std::istringstream input(test_lgf);
176  DigraphReader<Digraph>(g,input).
177    arcMap("capacity", cap).
178    node("source",s).
179    node("target",t).
180    run();
181
182  PType preflow_test(g, cap, s, t);
183  preflow_test.run();
184
185  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
186        "The flow is not feasible.");
187
188  CutMap min_cut(g);
189  preflow_test.minCutMap(min_cut);
190  int min_cut_value=cutValue(g,min_cut,cap);
191
192  check(preflow_test.flowValue() == min_cut_value,
193        "The max flow value is not equal to the three min cut values.");
194
195  FlowMap flow(g);
196  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
197
198  int flow_value=preflow_test.flowValue();
199
200  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
201  preflow_test.init(flow);
202  preflow_test.startFirstPhase();
203
204  CutMap min_cut1(g);
205  preflow_test.minCutMap(min_cut1);
206  min_cut_value=cutValue(g,min_cut1,cap);
207
208  check(preflow_test.flowValue() == min_cut_value &&
209        min_cut_value == 2*flow_value,
210        "The max flow value or the min cut value is wrong.");
211
212  preflow_test.startSecondPhase();
213
214  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
215        "The flow is not feasible.");
216
217  CutMap min_cut2(g);
218  preflow_test.minCutMap(min_cut2);
219  min_cut_value=cutValue(g,min_cut2,cap);
220
221  check(preflow_test.flowValue() == min_cut_value &&
222        min_cut_value == 2*flow_value,
223        "The max flow value or the three min cut values were not doubled");
224
225
226  preflow_test.flowMap(flow);
227
228  NodeIt tmp1(g,s);
229  ++tmp1;
230  if ( tmp1 != INVALID ) s=tmp1;
231
232  NodeIt tmp2(g,t);
233  ++tmp2;
234  if ( tmp2 != INVALID ) t=tmp2;
235
236  preflow_test.source(s);
237  preflow_test.target(t);
238
239  preflow_test.run();
240
241  CutMap min_cut3(g);
242  preflow_test.minCutMap(min_cut3);
243  min_cut_value=cutValue(g,min_cut3,cap);
244
245
246  check(preflow_test.flowValue() == min_cut_value,
247        "The max flow value or the three min cut values are incorrect.");
248
249  return 0;
250}
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