COIN-OR::LEMON - Graph Library

source: lemon/test/preflow_test.cc @ 1259:8b2d4e5d96e4

Last change on this file since 1259:8b2d4e5d96e4 was 1259:8b2d4e5d96e4, checked in by Alpar Juttner <alpar@…>, 6 years ago

Merge #294 to branches >=1.2

File size: 6.8 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) 2003-2010
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  ::lemon::ignore_unused_variable_warning(v,b);
90
91  typedef Preflow<Digraph, CapMap>
92            ::SetFlowMap<FlowMap>
93            ::SetElevator<Elev>
94            ::SetStandardElevator<LinkedElev>
95            ::Create PreflowType;
96  PreflowType preflow_test(g, cap, n, n);
97  const PreflowType& const_preflow_test = preflow_test;
98
99  const PreflowType::Elevator& elev = const_preflow_test.elevator();
100  preflow_test.elevator(const_cast<PreflowType::Elevator&>(elev));
101  PreflowType::Tolerance tol = const_preflow_test.tolerance();
102  preflow_test.tolerance(tol);
103
104  preflow_test
105    .capacityMap(cap)
106    .flowMap(flow)
107    .source(n)
108    .target(n);
109
110  preflow_test.init();
111  preflow_test.init(cap);
112  preflow_test.startFirstPhase();
113  preflow_test.startSecondPhase();
114  preflow_test.run();
115  preflow_test.runMinCut();
116
117  v = const_preflow_test.flowValue();
118  v = const_preflow_test.flow(e);
119  const FlowMap& fm = const_preflow_test.flowMap();
120  b = const_preflow_test.minCut(n);
121  const_preflow_test.minCutMap(cut);
122
123  ::lemon::ignore_unused_variable_warning(fm);
124}
125
126int cutValue (const SmartDigraph& g,
127              const SmartDigraph::NodeMap<bool>& cut,
128              const SmartDigraph::ArcMap<int>& cap) {
129
130  int c=0;
131  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
132    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
133  }
134  return c;
135}
136
137bool checkFlow(const SmartDigraph& g,
138               const SmartDigraph::ArcMap<int>& flow,
139               const SmartDigraph::ArcMap<int>& cap,
140               SmartDigraph::Node s, SmartDigraph::Node t) {
141
142  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
143    if (flow[e] < 0 || flow[e] > cap[e]) return false;
144  }
145
146  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
147    if (n == s || n == t) continue;
148    int sum = 0;
149    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
150      sum += flow[e];
151    }
152    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
153      sum -= flow[e];
154    }
155    if (sum != 0) return false;
156  }
157  return true;
158}
159
160void initFlowTest()
161{
162  DIGRAPH_TYPEDEFS(SmartDigraph);
163 
164  SmartDigraph g;
165  SmartDigraph::ArcMap<int> cap(g),iflow(g);
166  Node s=g.addNode(); Node t=g.addNode();
167  Node n1=g.addNode(); Node n2=g.addNode();
168  Arc a;
169  a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
170  a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
171  a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
172
173  Preflow<SmartDigraph> pre(g,cap,s,t);
174  pre.init(iflow);
175  pre.startFirstPhase();
176  check(pre.flowValue() == 10, "The incorrect max flow value.");
177  check(pre.minCut(s), "Wrong min cut (Node s).");
178  check(pre.minCut(n1), "Wrong min cut (Node n1).");
179  check(!pre.minCut(n2), "Wrong min cut (Node n2).");
180  check(!pre.minCut(t), "Wrong min cut (Node t).");
181}
182
183
184int main() {
185
186  typedef SmartDigraph Digraph;
187
188  typedef Digraph::Node Node;
189  typedef Digraph::NodeIt NodeIt;
190  typedef Digraph::ArcIt ArcIt;
191  typedef Digraph::ArcMap<int> CapMap;
192  typedef Digraph::ArcMap<int> FlowMap;
193  typedef Digraph::NodeMap<bool> CutMap;
194
195  typedef Preflow<Digraph, CapMap> PType;
196
197  Digraph g;
198  Node s, t;
199  CapMap cap(g);
200  std::istringstream input(test_lgf);
201  DigraphReader<Digraph>(g,input).
202    arcMap("capacity", cap).
203    node("source",s).
204    node("target",t).
205    run();
206
207  PType preflow_test(g, cap, s, t);
208  preflow_test.run();
209
210  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
211        "The flow is not feasible.");
212
213  CutMap min_cut(g);
214  preflow_test.minCutMap(min_cut);
215  int min_cut_value=cutValue(g,min_cut,cap);
216
217  check(preflow_test.flowValue() == min_cut_value,
218        "The max flow value is not equal to the three min cut values.");
219
220  FlowMap flow(g);
221  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
222
223  int flow_value=preflow_test.flowValue();
224
225  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
226  preflow_test.init(flow);
227  preflow_test.startFirstPhase();
228
229  CutMap min_cut1(g);
230  preflow_test.minCutMap(min_cut1);
231  min_cut_value=cutValue(g,min_cut1,cap);
232
233  check(preflow_test.flowValue() == min_cut_value &&
234        min_cut_value == 2*flow_value,
235        "The max flow value or the min cut value is wrong.");
236
237  preflow_test.startSecondPhase();
238
239  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
240        "The flow is not feasible.");
241
242  CutMap min_cut2(g);
243  preflow_test.minCutMap(min_cut2);
244  min_cut_value=cutValue(g,min_cut2,cap);
245
246  check(preflow_test.flowValue() == min_cut_value &&
247        min_cut_value == 2*flow_value,
248        "The max flow value or the three min cut values were not doubled");
249
250
251  preflow_test.flowMap(flow);
252
253  NodeIt tmp1(g,s);
254  ++tmp1;
255  if ( tmp1 != INVALID ) s=tmp1;
256
257  NodeIt tmp2(g,t);
258  ++tmp2;
259  if ( tmp2 != INVALID ) t=tmp2;
260
261  preflow_test.source(s);
262  preflow_test.target(t);
263
264  preflow_test.run();
265
266  CutMap min_cut3(g);
267  preflow_test.minCutMap(min_cut3);
268  min_cut_value=cutValue(g,min_cut3,cap);
269
270
271  check(preflow_test.flowValue() == min_cut_value,
272        "The max flow value or the three min cut values are incorrect.");
273
274  initFlowTest();
275 
276  return 0;
277}
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