COIN-OR::LEMON - Graph Library

source: lemon-1.2/test/preflow_test.cc @ 391:624e673efa76

Last change on this file since 391:624e673efa76 was 391:624e673efa76, checked in by Alpar Juttner <alpar@…>, 11 years ago

Def -> Set renaming in Preflow

File size: 5.1 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 *
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
29using namespace lemon;
30
31void checkPreflow()
32{
33  typedef int VType;
34  typedef concepts::Digraph Digraph;
35
36  typedef Digraph::Node Node;
37  typedef Digraph::Arc Arc;
38  typedef concepts::ReadMap<Arc,VType> CapMap;
39  typedef concepts::ReadWriteMap<Arc,VType> FlowMap;
40  typedef concepts::WriteMap<Node,bool> CutMap;
41
42  Digraph g;
43  Node n;
44  Arc e;
45  CapMap cap;
46  FlowMap flow;
47  CutMap cut;
48
[391]49  Preflow<Digraph, CapMap>::SetFlowMap<FlowMap>::Create preflow_test(g,cap,n,n);
[389]50
51  preflow_test.capacityMap(cap);
52  flow = preflow_test.flowMap();
53  preflow_test.flowMap(flow);
54  preflow_test.source(n);
55  preflow_test.target(n);
56
57  preflow_test.init();
58  preflow_test.flowInit(cap);
59  preflow_test.startFirstPhase();
60  preflow_test.startSecondPhase();
61  preflow_test.run();
62  preflow_test.runMinCut();
63
64  preflow_test.flowValue();
65  preflow_test.minCut(n);
66  preflow_test.minCutMap(cut);
67  preflow_test.flow(e);
68
69}
70
71int cutValue (const SmartDigraph& g,
72              const SmartDigraph::NodeMap<bool>& cut,
73              const SmartDigraph::ArcMap<int>& cap) {
74
75  int c=0;
76  for(SmartDigraph::ArcIt e(g); e!=INVALID; ++e) {
77    if (cut[g.source(e)] && !cut[g.target(e)]) c+=cap[e];
78  }
79  return c;
80}
81
82bool checkFlow(const SmartDigraph& g,
83               const SmartDigraph::ArcMap<int>& flow,
84               const SmartDigraph::ArcMap<int>& cap,
85               SmartDigraph::Node s, SmartDigraph::Node t) {
86
87  for (SmartDigraph::ArcIt e(g); e != INVALID; ++e) {
88    if (flow[e] < 0 || flow[e] > cap[e]) return false;
89  }
90
91  for (SmartDigraph::NodeIt n(g); n != INVALID; ++n) {
92    if (n == s || n == t) continue;
93    int sum = 0;
94    for (SmartDigraph::OutArcIt e(g, n); e != INVALID; ++e) {
95      sum += flow[e];
96    }
97    for (SmartDigraph::InArcIt e(g, n); e != INVALID; ++e) {
98      sum -= flow[e];
99    }
100    if (sum != 0) return false;
101  }
102  return true;
103}
104
105int main() {
106
107  typedef SmartDigraph Digraph;
108
109  typedef Digraph::Node Node;
110  typedef Digraph::NodeIt NodeIt;
111  typedef Digraph::ArcIt ArcIt;
112  typedef Digraph::ArcMap<int> CapMap;
113  typedef Digraph::ArcMap<int> FlowMap;
114  typedef Digraph::NodeMap<bool> CutMap;
115
116  typedef Preflow<Digraph, CapMap> PType;
117
118  std::string f_name;
119  if( getenv("srcdir") )
120    f_name = std::string(getenv("srcdir"));
121  else f_name = ".";
122  f_name += "/test/preflow_graph.lgf";
123
124  std::ifstream file(f_name.c_str());
125
126  check(file, "Input file '" << f_name << "' not found.");
127
128  Digraph g;
129  Node s, t;
130  CapMap cap(g);
131  DigraphReader<Digraph>(g,file).
132    arcMap("capacity", cap).
133    node("source",s).
134    node("target",t).
135    run();
136
137  PType preflow_test(g, cap, s, t);
138  preflow_test.run();
139
140  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
141        "The flow is not feasible.");
142
143  CutMap min_cut(g);
144  preflow_test.minCutMap(min_cut);
145  int min_cut_value=cutValue(g,min_cut,cap);
146
147  check(preflow_test.flowValue() == min_cut_value,
148        "The max flow value is not equal to the three min cut values.");
149
150  FlowMap flow(g);
151  for(ArcIt e(g); e!=INVALID; ++e) flow[e] = preflow_test.flowMap()[e];
152
153  int flow_value=preflow_test.flowValue();
154
155  for(ArcIt e(g); e!=INVALID; ++e) cap[e]=2*cap[e];
156  preflow_test.flowInit(flow);
157  preflow_test.startFirstPhase();
158
159  CutMap min_cut1(g);
160  preflow_test.minCutMap(min_cut1);
161  min_cut_value=cutValue(g,min_cut1,cap);
162
163  check(preflow_test.flowValue() == min_cut_value &&
164        min_cut_value == 2*flow_value,
165        "The max flow value or the min cut value is wrong.");
166
167  preflow_test.startSecondPhase();
168
169  check(checkFlow(g, preflow_test.flowMap(), cap, s, t),
170        "The flow is not feasible.");
171
172  CutMap min_cut2(g);
173  preflow_test.minCutMap(min_cut2);
174  min_cut_value=cutValue(g,min_cut2,cap);
175
176  check(preflow_test.flowValue() == min_cut_value &&
177        min_cut_value == 2*flow_value,
178        "The max flow value or the three min cut values were not doubled");
179
180
181  preflow_test.flowMap(flow);
182
183  NodeIt tmp1(g,s);
184  ++tmp1;
185  if ( tmp1 != INVALID ) s=tmp1;
186
187  NodeIt tmp2(g,t);
188  ++tmp2;
189  if ( tmp2 != INVALID ) t=tmp2;
190
191  preflow_test.source(s);
192  preflow_test.target(t);
193
194  preflow_test.run();
195
196  CutMap min_cut3(g);
197  preflow_test.minCutMap(min_cut3);
198  min_cut_value=cutValue(g,min_cut3,cap);
199
200
201  check(preflow_test.flowValue() == min_cut_value,
202        "The max flow value or the three min cut values are incorrect.");
203
204  return 0;
205}
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