COIN-OR::LEMON - Graph Library

source: lemon/test/preflow_test.cc @ 409:e7707b3069f1

Last change on this file since 409:e7707b3069f1 was 409:e7707b3069f1, checked in by Peter Kovacs <kpeter@…>, 11 years ago

Better test files for Preflow (#176)

  • Slightly improve preflow_test.cc.
  • Change preflow_test.lgf to meet the new LGF format and remove trailing tabs.
File size: 5.3 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) 2003-2008
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 <fstream>
20#include <string>
21
22#include "test_tools.h"
23#include <lemon/smart_graph.h>
24#include <lemon/preflow.h>
25#include <lemon/concepts/digraph.h>
26#include <lemon/concepts/maps.h>
27#include <lemon/lgf_reader.h>
28#include <lemon/elevator.h>
29
30using namespace lemon;
31
32void checkPreflowCompile()
33{
34  typedef int VType;
35  typedef concepts::Digraph Digraph;
36
37  typedef Digraph::Node Node;
38  typedef Digraph::Arc Arc;
39  typedef concepts::ReadMap<Arc,VType> CapMap;
40  typedef concepts::ReadWriteMap<Arc,VType> FlowMap;
41  typedef concepts::WriteMap<Node,bool> CutMap;
42
43  typedef Elevator<Digraph, Digraph::Node> Elev;
44  typedef LinkedElevator<Digraph, Digraph::Node> LinkedElev;
45
46  Digraph g;
47  Node n;
48  Arc e;
49  CapMap cap;
50  FlowMap flow;
51  CutMap cut;
52
53  Preflow<Digraph, CapMap>
54    ::SetFlowMap<FlowMap>
55    ::SetElevator<Elev>
56    ::SetStandardElevator<LinkedElev>
57    ::Create preflow_test(g,cap,n,n);
58
59  preflow_test.capacityMap(cap);
60  flow = preflow_test.flowMap();
61  preflow_test.flowMap(flow);
62  preflow_test.source(n);
63  preflow_test.target(n);
64
65  preflow_test.init();
66  preflow_test.init(cap);
67  preflow_test.startFirstPhase();
68  preflow_test.startSecondPhase();
69  preflow_test.run();
70  preflow_test.runMinCut();
71
72  preflow_test.flowValue();
73  preflow_test.minCut(n);
74  preflow_test.minCutMap(cut);
75  preflow_test.flow(e);
76
77}
78
79int cutValue (const SmartDigraph& g,
80              const SmartDigraph::NodeMap<bool>& cut,
81              const SmartDigraph::ArcMap<int>& cap) {
82
83  int c=0;
84  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
85    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
86  }
87  return c;
88}
89
90bool checkFlow(const SmartDigraph& g,
91               const SmartDigraph::ArcMap<int>& flow,
92               const SmartDigraph::ArcMap<int>& cap,
93               SmartDigraph::Node s, SmartDigraph::Node t) {
94
95  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
96    if (flow[e] < 0 || flow[e] > cap[e]) return false;
97  }
98
99  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
100    if (n == s || n == t) continue;
101    int sum = 0;
102    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
103      sum += flow[e];
104    }
105    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
106      sum -= flow[e];
107    }
108    if (sum != 0) return false;
109  }
110  return true;
111}
112
113int main() {
114
115  typedef SmartDigraph Digraph;
116
117  typedef Digraph::Node Node;
118  typedef Digraph::NodeIt NodeIt;
119  typedef Digraph::ArcIt ArcIt;
120  typedef Digraph::ArcMap<int> CapMap;
121  typedef Digraph::ArcMap<int> FlowMap;
122  typedef Digraph::NodeMap<bool> CutMap;
123
124  typedef Preflow<Digraph, CapMap> PType;
125
126  std::string f_name;
127  if( getenv("srcdir") )
128    f_name = std::string(getenv("srcdir"));
129  else f_name = ".";
130  f_name += "/test/preflow_graph.lgf";
131
132  std::ifstream file(f_name.c_str());
133
134  check(file, "Input file '" << f_name << "' not found.");
135
136  Digraph g;
137  Node s, t;
138  CapMap cap(g);
139  DigraphReader<Digraph>(g,file).
140    arcMap("capacity", cap).
141    node("source",s).
142    node("target",t).
143    run();
144
145  PType preflow_test(g, cap, s, t);
146  preflow_test.run();
147
148  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
149        "The flow is not feasible.");
150
151  CutMap min_cut(g);
152  preflow_test.minCutMap(min_cut);
153  int min_cut_value=cutValue(g,min_cut,cap);
154
155  check(preflow_test.flowValue() == min_cut_value,
156        "The max flow value is not equal to the three min cut values.");
157
158  FlowMap flow(g);
159  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
160
161  int flow_value=preflow_test.flowValue();
162
163  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
164  preflow_test.init(flow);
165  preflow_test.startFirstPhase();
166
167  CutMap min_cut1(g);
168  preflow_test.minCutMap(min_cut1);
169  min_cut_value=cutValue(g,min_cut1,cap);
170
171  check(preflow_test.flowValue() == min_cut_value &&
172        min_cut_value == 2*flow_value,
173        "The max flow value or the min cut value is wrong.");
174
175  preflow_test.startSecondPhase();
176
177  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
178        "The flow is not feasible.");
179
180  CutMap min_cut2(g);
181  preflow_test.minCutMap(min_cut2);
182  min_cut_value=cutValue(g,min_cut2,cap);
183
184  check(preflow_test.flowValue() == min_cut_value &&
185        min_cut_value == 2*flow_value,
186        "The max flow value or the three min cut values were not doubled");
187
188
189  preflow_test.flowMap(flow);
190
191  NodeIt tmp1(g,s);
192  ++tmp1;
193  if ( tmp1 != INVALID ) s=tmp1;
194
195  NodeIt tmp2(g,t);
196  ++tmp2;
197  if ( tmp2 != INVALID ) t=tmp2;
198
199  preflow_test.source(s);
200  preflow_test.target(t);
201
202  preflow_test.run();
203
204  CutMap min_cut3(g);
205  preflow_test.minCutMap(min_cut3);
206  min_cut_value=cutValue(g,min_cut3,cap);
207
208
209  check(preflow_test.flowValue() == min_cut_value,
210        "The max flow value or the three min cut values are incorrect.");
211
212  return 0;
213}
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