COIN-OR::LEMON - Graph Library

source: lemon/test/preflow_test.cc @ 1027:30d5f950aa5f

Last change on this file since 1027:30d5f950aa5f was 1027:30d5f950aa5f, checked in by Alpar Juttner <alpar@…>, 9 years ago

Fix wrong initialization in Preflow (#414)

File size: 6.5 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  preflow_test
99    .capacityMap(cap)
100    .flowMap(flow)
101    .source(n)
102    .target(n);
103
104  preflow_test.init();
105  preflow_test.init(cap);
106  preflow_test.startFirstPhase();
107  preflow_test.startSecondPhase();
108  preflow_test.run();
109  preflow_test.runMinCut();
110
111  v = const_preflow_test.flowValue();
112  v = const_preflow_test.flow(e);
113  const FlowMap& fm = const_preflow_test.flowMap();
114  b = const_preflow_test.minCut(n);
115  const_preflow_test.minCutMap(cut);
116 
117  ignore_unused_variable_warning(fm);
118}
119
120int cutValue (const SmartDigraph& g,
121              const SmartDigraph::NodeMap<bool>& cut,
122              const SmartDigraph::ArcMap<int>& cap) {
123
124  int c=0;
125  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
126    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
127  }
128  return c;
129}
130
131bool checkFlow(const SmartDigraph& g,
132               const SmartDigraph::ArcMap<int>& flow,
133               const SmartDigraph::ArcMap<int>& cap,
134               SmartDigraph::Node s, SmartDigraph::Node t) {
135
136  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
137    if (flow[e] < 0 || flow[e] > cap[e]) return false;
138  }
139
140  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
141    if (n == s || n == t) continue;
142    int sum = 0;
143    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
144      sum += flow[e];
145    }
146    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
147      sum -= flow[e];
148    }
149    if (sum != 0) return false;
150  }
151  return true;
152}
153
154void initFlowTest()
155{
156  DIGRAPH_TYPEDEFS(SmartDigraph);
157 
158  SmartDigraph g;
159  SmartDigraph::ArcMap<int> cap(g),iflow(g);
160  Node s=g.addNode(); Node t=g.addNode();
161  Node n1=g.addNode(); Node n2=g.addNode();
162  Arc a;
163  a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
164  a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
165  a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
166
167  Preflow<SmartDigraph> pre(g,cap,s,t);
168  pre.init(iflow);
169  pre.startFirstPhase();
170  check(pre.flowValue() == 10, "The incorrect max flow value.");
171  check(pre.minCut(s), "Wrong min cut (Node s).");
172  check(pre.minCut(n1), "Wrong min cut (Node n1).");
173  check(!pre.minCut(n2), "Wrong min cut (Node n2).");
174  check(!pre.minCut(t), "Wrong min cut (Node t).");
175}
176
177
178int main() {
179
180  typedef SmartDigraph Digraph;
181
182  typedef Digraph::Node Node;
183  typedef Digraph::NodeIt NodeIt;
184  typedef Digraph::ArcIt ArcIt;
185  typedef Digraph::ArcMap<int> CapMap;
186  typedef Digraph::ArcMap<int> FlowMap;
187  typedef Digraph::NodeMap<bool> CutMap;
188
189  typedef Preflow<Digraph, CapMap> PType;
190
191  Digraph g;
192  Node s, t;
193  CapMap cap(g);
194  std::istringstream input(test_lgf);
195  DigraphReader<Digraph>(g,input).
196    arcMap("capacity", cap).
197    node("source",s).
198    node("target",t).
199    run();
200
201  PType preflow_test(g, cap, s, t);
202  preflow_test.run();
203
204  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
205        "The flow is not feasible.");
206
207  CutMap min_cut(g);
208  preflow_test.minCutMap(min_cut);
209  int min_cut_value=cutValue(g,min_cut,cap);
210
211  check(preflow_test.flowValue() == min_cut_value,
212        "The max flow value is not equal to the three min cut values.");
213
214  FlowMap flow(g);
215  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
216
217  int flow_value=preflow_test.flowValue();
218
219  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
220  preflow_test.init(flow);
221  preflow_test.startFirstPhase();
222
223  CutMap min_cut1(g);
224  preflow_test.minCutMap(min_cut1);
225  min_cut_value=cutValue(g,min_cut1,cap);
226
227  check(preflow_test.flowValue() == min_cut_value &&
228        min_cut_value == 2*flow_value,
229        "The max flow value or the min cut value is wrong.");
230
231  preflow_test.startSecondPhase();
232
233  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
234        "The flow is not feasible.");
235
236  CutMap min_cut2(g);
237  preflow_test.minCutMap(min_cut2);
238  min_cut_value=cutValue(g,min_cut2,cap);
239
240  check(preflow_test.flowValue() == min_cut_value &&
241        min_cut_value == 2*flow_value,
242        "The max flow value or the three min cut values were not doubled");
243
244
245  preflow_test.flowMap(flow);
246
247  NodeIt tmp1(g,s);
248  ++tmp1;
249  if ( tmp1 != INVALID ) s=tmp1;
250
251  NodeIt tmp2(g,t);
252  ++tmp2;
253  if ( tmp2 != INVALID ) t=tmp2;
254
255  preflow_test.source(s);
256  preflow_test.target(t);
257
258  preflow_test.run();
259
260  CutMap min_cut3(g);
261  preflow_test.minCutMap(min_cut3);
262  min_cut_value=cutValue(g,min_cut3,cap);
263
264
265  check(preflow_test.flowValue() == min_cut_value,
266        "The max flow value or the three min cut values are incorrect.");
267
268  initFlowTest();
269 
270  return 0;
271}
Note: See TracBrowser for help on using the repository browser.