COIN-OR::LEMON - Graph Library

source: lemon-1.2/test/preflow_test.cc @ 619:ec817dfc2cb7

Last change on this file since 619:ec817dfc2cb7 was 585:65fbcf2f978a, checked in by Peter Kovacs <kpeter@…>, 10 years ago

Improve test files for some algorithms (#263)

File size: 5.8 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) 2003-2009
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
154int main() {
155
156  typedef SmartDigraph Digraph;
157
158  typedef Digraph::Node Node;
159  typedef Digraph::NodeIt NodeIt;
160  typedef Digraph::ArcIt ArcIt;
161  typedef Digraph::ArcMap<int> CapMap;
162  typedef Digraph::ArcMap<int> FlowMap;
163  typedef Digraph::NodeMap<bool> CutMap;
164
165  typedef Preflow<Digraph, CapMap> PType;
166
167  Digraph g;
168  Node s, t;
169  CapMap cap(g);
170  std::istringstream input(test_lgf);
171  DigraphReader<Digraph>(g,input).
172    arcMap("capacity", cap).
173    node("source",s).
174    node("target",t).
175    run();
176
177  PType preflow_test(g, cap, s, t);
178  preflow_test.run();
179
180  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
181        "The flow is not feasible.");
182
183  CutMap min_cut(g);
184  preflow_test.minCutMap(min_cut);
185  int min_cut_value=cutValue(g,min_cut,cap);
186
187  check(preflow_test.flowValue() == min_cut_value,
188        "The max flow value is not equal to the three min cut values.");
189
190  FlowMap flow(g);
191  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
192
193  int flow_value=preflow_test.flowValue();
194
195  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
196  preflow_test.init(flow);
197  preflow_test.startFirstPhase();
198
199  CutMap min_cut1(g);
200  preflow_test.minCutMap(min_cut1);
201  min_cut_value=cutValue(g,min_cut1,cap);
202
203  check(preflow_test.flowValue() == min_cut_value &&
204        min_cut_value == 2*flow_value,
205        "The max flow value or the min cut value is wrong.");
206
207  preflow_test.startSecondPhase();
208
209  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
210        "The flow is not feasible.");
211
212  CutMap min_cut2(g);
213  preflow_test.minCutMap(min_cut2);
214  min_cut_value=cutValue(g,min_cut2,cap);
215
216  check(preflow_test.flowValue() == min_cut_value &&
217        min_cut_value == 2*flow_value,
218        "The max flow value or the three min cut values were not doubled");
219
220
221  preflow_test.flowMap(flow);
222
223  NodeIt tmp1(g,s);
224  ++tmp1;
225  if ( tmp1 != INVALID ) s=tmp1;
226
227  NodeIt tmp2(g,t);
228  ++tmp2;
229  if ( tmp2 != INVALID ) t=tmp2;
230
231  preflow_test.source(s);
232  preflow_test.target(t);
233
234  preflow_test.run();
235
236  CutMap min_cut3(g);
237  preflow_test.minCutMap(min_cut3);
238  min_cut_value=cutValue(g,min_cut3,cap);
239
240
241  check(preflow_test.flowValue() == min_cut_value,
242        "The max flow value or the three min cut values are incorrect.");
243
244  return 0;
245}
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