COIN-OR::LEMON - Graph Library

source: lemon-1.2/test/preflow_test.cc @ 969:7e368d9b67f7

Last change on this file since 969:7e368d9b67f7 was 969:7e368d9b67f7, checked in by Alpar Juttner <alpar@…>, 7 years ago

Avoid GCC 4.7 compiler warnings (#453)

File size: 6.5 KB
RevLine 
[389]1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
[440]5 * Copyright (C) 2003-2009
[389]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
[423]19#include <iostream>
[389]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>
[394]27#include <lemon/elevator.h>
[389]28
29using namespace lemon;
30
[423]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
[394]67void checkPreflowCompile()
[389]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
[394]78  typedef Elevator<Digraph, Digraph::Node> Elev;
79  typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;
80
[389]81  Digraph g;
82  Node n;
83  Arc e;
84  CapMap cap;
85  FlowMap flow;
86  CutMap cut;
[585]87  VType v;
88  bool b;
[969]89  ignore_unused_variable_warning(v,b);
[389]90
[585]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;
[389]98
[585]99  preflow_test
100    .capacityMap(cap)
101    .flowMap(flow)
102    .source(n)
103    .target(n);
[389]104
105  preflow_test.init();
[392]106  preflow_test.init(cap);
[389]107  preflow_test.startFirstPhase();
108  preflow_test.startSecondPhase();
109  preflow_test.run();
110  preflow_test.runMinCut();
111
[585]112  v = const_preflow_test.flowValue();
113  v = const_preflow_test.flow(e);
114  const FlowMap& fm = const_preflow_test.flowMap();
115  b = const_preflow_test.minCut(n);
116  const_preflow_test.minCutMap(cut);
117 
118  ignore_unused_variable_warning(fm);
[389]119}
120
121int cutValue (const SmartDigraph& g,
122              const SmartDigraph::NodeMap<bool>& cut,
123              const SmartDigraph::ArcMap<int>& cap) {
124
125  int c=0;
126  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
127    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
128  }
129  return c;
130}
131
132bool checkFlow(const SmartDigraph& g,
133               const SmartDigraph::ArcMap<int>& flow,
134               const SmartDigraph::ArcMap<int>& cap,
135               SmartDigraph::Node s, SmartDigraph::Node t) {
136
137  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
138    if (flow[e] < 0 || flow[e] > cap[e]) return false;
139  }
140
141  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
142    if (n == s || n == t) continue;
143    int sum = 0;
144    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
145      sum += flow[e];
146    }
147    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
148      sum -= flow[e];
149    }
150    if (sum != 0) return false;
151  }
152  return true;
153}
154
[901]155void initFlowTest()
156{
157  DIGRAPH_TYPEDEFS(SmartDigraph);
158 
159  SmartDigraph g;
160  SmartDigraph::ArcMap<int> cap(g),iflow(g);
161  Node s=g.addNode(); Node t=g.addNode();
162  Node n1=g.addNode(); Node n2=g.addNode();
163  Arc a;
164  a=g.addArc(s,n1); cap[a]=20; iflow[a]=20;
165  a=g.addArc(n1,n2); cap[a]=10; iflow[a]=0;
166  a=g.addArc(n2,t); cap[a]=20; iflow[a]=0;
167
168  Preflow<SmartDigraph> pre(g,cap,s,t);
169  pre.init(iflow);
170  pre.startFirstPhase();
171  check(pre.flowValue() == 10, "The incorrect max flow value.");
172  check(pre.minCut(s), "Wrong min cut (Node s).");
173  check(pre.minCut(n1), "Wrong min cut (Node n1).");
174  check(!pre.minCut(n2), "Wrong min cut (Node n2).");
175  check(!pre.minCut(t), "Wrong min cut (Node t).");
176}
177
178
[389]179int main() {
180
181  typedef SmartDigraph Digraph;
182
183  typedef Digraph::Node Node;
184  typedef Digraph::NodeIt NodeIt;
185  typedef Digraph::ArcIt ArcIt;
186  typedef Digraph::ArcMap<int> CapMap;
187  typedef Digraph::ArcMap<int> FlowMap;
188  typedef Digraph::NodeMap<bool> CutMap;
189
190  typedef Preflow<Digraph, CapMap> PType;
191
192  Digraph g;
193  Node s, t;
194  CapMap cap(g);
[423]195  std::istringstream input(test_lgf);
196  DigraphReader<Digraph>(g,input).
[389]197    arcMap("capacity", cap).
198    node("source",s).
199    node("target",t).
200    run();
201
202  PType preflow_test(g, cap, s, t);
203  preflow_test.run();
204
205  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
206        "The flow is not feasible.");
207
208  CutMap min_cut(g);
209  preflow_test.minCutMap(min_cut);
210  int min_cut_value=cutValue(g,min_cut,cap);
211
212  check(preflow_test.flowValue() == min_cut_value,
213        "The max flow value is not equal to the three min cut values.");
214
215  FlowMap flow(g);
216  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
217
218  int flow_value=preflow_test.flowValue();
219
220  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
[392]221  preflow_test.init(flow);
[389]222  preflow_test.startFirstPhase();
223
224  CutMap min_cut1(g);
225  preflow_test.minCutMap(min_cut1);
226  min_cut_value=cutValue(g,min_cut1,cap);
227
228  check(preflow_test.flowValue() == min_cut_value &&
229        min_cut_value == 2*flow_value,
230        "The max flow value or the min cut value is wrong.");
231
232  preflow_test.startSecondPhase();
233
234  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
235        "The flow is not feasible.");
236
237  CutMap min_cut2(g);
238  preflow_test.minCutMap(min_cut2);
239  min_cut_value=cutValue(g,min_cut2,cap);
240
241  check(preflow_test.flowValue() == min_cut_value &&
242        min_cut_value == 2*flow_value,
243        "The max flow value or the three min cut values were not doubled");
244
245
246  preflow_test.flowMap(flow);
247
248  NodeIt tmp1(g,s);
249  ++tmp1;
250  if ( tmp1 != INVALID ) s=tmp1;
251
252  NodeIt tmp2(g,t);
253  ++tmp2;
254  if ( tmp2 != INVALID ) t=tmp2;
255
256  preflow_test.source(s);
257  preflow_test.target(t);
258
259  preflow_test.run();
260
261  CutMap min_cut3(g);
262  preflow_test.minCutMap(min_cut3);
263  min_cut_value=cutValue(g,min_cut3,cap);
264
265
266  check(preflow_test.flowValue() == min_cut_value,
267        "The max flow value or the three min cut values are incorrect.");
268
[901]269  initFlowTest();
270 
[389]271  return 0;
272}
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