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kpeter (Peter Kovacs)
kpeter@inf.elte.hu
Improvements for the Euler tools and the test file (#264)
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2 files changed with 238 insertions and 157 deletions:
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Ignore white space 6 line context
... ...
@@ -28,7 +28,7 @@
28 28
/// \file
29
/// \brief Euler tour
29
/// \brief Euler tour iterators and a function for checking the \e Eulerian 
30
/// property.
30 31
///
31
///This file provides an Euler tour iterator and ways to check
32
///if a digraph is euler.
33

	
32
///This file provides Euler tour iterators and a function to check
33
///if a (di)graph is \e Eulerian.
34 34

	
... ...
@@ -36,21 +36,19 @@
36 36

	
37
  ///Euler iterator for digraphs.
37
  ///Euler tour iterator for digraphs.
38 38

	
39
  /// \ingroup graph_properties
40
  ///This iterator converts to the \c Arc type of the digraph and using
41
  ///operator ++, it provides an Euler tour of a \e directed
42
  ///graph (if there exists).
39
  /// \ingroup graph_prop
40
  ///This iterator provides an Euler tour (Eulerian circuit) of a \e directed
41
  ///graph (if there exists) and it converts to the \c Arc type of the digraph.
43 42
  ///
44
  ///For example
45
  ///if the given digraph is Euler (i.e it has only one nontrivial component
46
  ///and the in-degree is equal to the out-degree for all nodes),
47
  ///the following code will put the arcs of \c g
48
  ///to the vector \c et according to an
49
  ///Euler tour of \c g.
43
  ///For example, if the given digraph has an Euler tour (i.e it has only one
44
  ///non-trivial component and the in-degree is equal to the out-degree 
45
  ///for all nodes), then the following code will put the arcs of \c g
46
  ///to the vector \c et according to an Euler tour of \c g.
50 47
  ///\code
51 48
  ///  std::vector<ListDigraph::Arc> et;
52
  ///  for(DiEulerIt<ListDigraph> e(g),e!=INVALID;++e)
49
  ///  for(DiEulerIt<ListDigraph> e(g); e!=INVALID; ++e)
53 50
  ///    et.push_back(e);
54 51
  ///\endcode
55
  ///If \c g is not Euler then the resulted tour will not be full or closed.
52
  ///If \c g has no Euler tour, then the resulted walk will not be closed
53
  ///or not contain all arcs.
56 54
  ///\sa EulerIt
... ...
@@ -67,3 +65,3 @@
67 65
    const GR &g;
68
    typename GR::template NodeMap<OutArcIt> nedge;
66
    typename GR::template NodeMap<OutArcIt> narc;
69 67
    std::list<Arc> euler;
... ...
@@ -74,7 +72,8 @@
74 72

	
73
    ///Constructor.
75 74
    ///\param gr A digraph.
76
    ///\param start The starting point of the tour. If it is not given
77
    ///       the tour will start from the first node.
75
    ///\param start The starting point of the tour. If it is not given,
76
    ///the tour will start from the first node that has an outgoing arc.
78 77
    DiEulerIt(const GR &gr, typename GR::Node start = INVALID)
79
      : g(gr), nedge(g)
78
      : g(gr), narc(g)
80 79
    {
... ...
@@ -86,7 +85,7 @@
86 85
      if (start!=INVALID) {
87
        for (NodeIt n(g); n!=INVALID; ++n) nedge[n]=OutArcIt(g,n);
88
        while (nedge[start]!=INVALID) {
89
          euler.push_back(nedge[start]);
90
          Node next=g.target(nedge[start]);
91
          ++nedge[start];
86
        for (NodeIt n(g); n!=INVALID; ++n) narc[n]=OutArcIt(g,n);
87
        while (narc[start]!=INVALID) {
88
          euler.push_back(narc[start]);
89
          Node next=g.target(narc[start]);
90
          ++narc[start];
92 91
          start=next;
... ...
@@ -96,5 +95,7 @@
96 95

	
97
    ///Arc Conversion
96
    ///Arc conversion
98 97
    operator Arc() { return euler.empty()?INVALID:euler.front(); }
98
    ///Compare with \c INVALID
99 99
    bool operator==(Invalid) { return euler.empty(); }
100
    ///Compare with \c INVALID
100 101
    bool operator!=(Invalid) { return !euler.empty(); }
... ...
@@ -102,2 +103,5 @@
102 103
    ///Next arc of the tour
104

	
105
    ///Next arc of the tour
106
    ///
103 107
    DiEulerIt &operator++() {
... ...
@@ -105,9 +109,7 @@
105 109
      euler.pop_front();
106
      //This produces a warning.Strange.
107
      //std::list<Arc>::iterator next=euler.begin();
108 110
      typename std::list<Arc>::iterator next=euler.begin();
109
      while(nedge[s]!=INVALID) {
110
        euler.insert(next,nedge[s]);
111
        Node n=g.target(nedge[s]);
112
        ++nedge[s];
111
      while(narc[s]!=INVALID) {
112
        euler.insert(next,narc[s]);
113
        Node n=g.target(narc[s]);
114
        ++narc[s];
113 115
        s=n;
... ...
@@ -118,4 +120,6 @@
118 120

	
121
    /// Postfix incrementation.
122
    ///
119 123
    ///\warning This incrementation
120
    ///returns an \c Arc, not an \ref DiEulerIt, as one may
124
    ///returns an \c Arc, not a \ref DiEulerIt, as one may
121 125
    ///expect.
... ...
@@ -129,13 +133,11 @@
129 133

	
130
  ///Euler iterator for graphs.
134
  ///Euler tour iterator for graphs.
131 135

	
132 136
  /// \ingroup graph_properties
133
  ///This iterator converts to the \c Arc (or \c Edge)
134
  ///type of the digraph and using
135
  ///operator ++, it provides an Euler tour of an undirected
136
  ///digraph (if there exists).
137
  ///This iterator provides an Euler tour (Eulerian circuit) of an
138
  ///\e undirected graph (if there exists) and it converts to the \c Arc
139
  ///and \c Edge types of the graph.
137 140
  ///
138
  ///For example
139
  ///if the given digraph if Euler (i.e it has only one nontrivial component
140
  ///and the degree of each node is even),
141
  ///For example, if the given graph has an Euler tour (i.e it has only one 
142
  ///non-trivial component and the degree of each node is even),
141 143
  ///the following code will print the arc IDs according to an
... ...
@@ -143,3 +145,3 @@
143 145
  ///\code
144
  ///  for(EulerIt<ListGraph> e(g),e!=INVALID;++e) {
146
  ///  for(EulerIt<ListGraph> e(g); e!=INVALID; ++e) {
145 147
  ///    std::cout << g.id(Edge(e)) << std::eol;
... ...
@@ -147,8 +149,8 @@
147 149
  ///\endcode
148
  ///Although the iterator provides an Euler tour of an graph,
149
  ///it still returns Arcs in order to indicate the direction of the tour.
150
  ///(But Arc will convert to Edges, of course).
150
  ///Although this iterator is for undirected graphs, it still returns 
151
  ///arcs in order to indicate the direction of the tour.
152
  ///(But arcs convert to edges, of course.)
151 153
  ///
152
  ///If \c g is not Euler then the resulted tour will not be full or closed.
153
  ///\sa EulerIt
154
  ///If \c g has no Euler tour, then the resulted walk will not be closed
155
  ///or not contain all edges.
154 156
  template<typename GR>
... ...
@@ -165,3 +167,3 @@
165 167
    const GR &g;
166
    typename GR::template NodeMap<OutArcIt> nedge;
168
    typename GR::template NodeMap<OutArcIt> narc;
167 169
    typename GR::template EdgeMap<bool> visited;
... ...
@@ -173,7 +175,8 @@
173 175

	
174
    ///\param gr An graph.
175
    ///\param start The starting point of the tour. If it is not given
176
    ///       the tour will start from the first node.
176
    ///Constructor.
177
    ///\param gr A graph.
178
    ///\param start The starting point of the tour. If it is not given,
179
    ///the tour will start from the first node that has an incident edge.
177 180
    EulerIt(const GR &gr, typename GR::Node start = INVALID)
178
      : g(gr), nedge(g), visited(g, false)
181
      : g(gr), narc(g), visited(g, false)
179 182
    {
... ...
@@ -185,10 +188,10 @@
185 188
      if (start!=INVALID) {
186
        for (NodeIt n(g); n!=INVALID; ++n) nedge[n]=OutArcIt(g,n);
187
        while(nedge[start]!=INVALID) {
188
          euler.push_back(nedge[start]);
189
          visited[nedge[start]]=true;
190
          Node next=g.target(nedge[start]);
191
          ++nedge[start];
189
        for (NodeIt n(g); n!=INVALID; ++n) narc[n]=OutArcIt(g,n);
190
        while(narc[start]!=INVALID) {
191
          euler.push_back(narc[start]);
192
          visited[narc[start]]=true;
193
          Node next=g.target(narc[start]);
194
          ++narc[start];
192 195
          start=next;
193
          while(nedge[start]!=INVALID && visited[nedge[start]]) ++nedge[start];
196
          while(narc[start]!=INVALID && visited[narc[start]]) ++narc[start];
194 197
        }
... ...
@@ -197,9 +200,9 @@
197 200

	
198
    ///Arc Conversion
201
    ///Arc conversion
199 202
    operator Arc() const { return euler.empty()?INVALID:euler.front(); }
200
    ///Arc Conversion
203
    ///Edge conversion
201 204
    operator Edge() const { return euler.empty()?INVALID:euler.front(); }
202
    ///\e
205
    ///Compare with \c INVALID
203 206
    bool operator==(Invalid) const { return euler.empty(); }
204
    ///\e
207
    ///Compare with \c INVALID
205 208
    bool operator!=(Invalid) const { return !euler.empty(); }
... ...
@@ -207,2 +210,5 @@
207 210
    ///Next arc of the tour
211

	
212
    ///Next arc of the tour
213
    ///
208 214
    EulerIt &operator++() {
... ...
@@ -211,11 +217,10 @@
211 217
      typename std::list<Arc>::iterator next=euler.begin();
212

	
213
      while(nedge[s]!=INVALID) {
214
        while(nedge[s]!=INVALID && visited[nedge[s]]) ++nedge[s];
215
        if(nedge[s]==INVALID) break;
218
      while(narc[s]!=INVALID) {
219
        while(narc[s]!=INVALID && visited[narc[s]]) ++narc[s];
220
        if(narc[s]==INVALID) break;
216 221
        else {
217
          euler.insert(next,nedge[s]);
218
          visited[nedge[s]]=true;
219
          Node n=g.target(nedge[s]);
220
          ++nedge[s];
222
          euler.insert(next,narc[s]);
223
          visited[narc[s]]=true;
224
          Node n=g.target(narc[s]);
225
          ++narc[s];
221 226
          s=n;
... ...
@@ -228,5 +233,6 @@
228 233

	
229
    ///\warning This incrementation
230
    ///returns an \c Arc, not an \ref EulerIt, as one may
231
    ///expect.
234
    /// Postfix incrementation.
235
    ///
236
    ///\warning This incrementation returns an \c Arc (which converts to 
237
    ///an \c Edge), not an \ref EulerIt, as one may expect.
232 238
    Arc operator++(int)
... ...
@@ -240,14 +246,19 @@
240 246

	
241
  ///Checks if the graph is Eulerian
247
  ///Check if the given graph is \e Eulerian
242 248

	
243 249
  /// \ingroup graph_properties
244
  ///Checks if the graph is Eulerian. It works for both directed and undirected
245
  ///graphs.
246
  ///\note By definition, a digraph is called \e Eulerian if
247
  ///and only if it is connected and the number of its incoming and outgoing
250
  ///This function checks if the given graph is \e Eulerian.
251
  ///It works for both directed and undirected graphs.
252
  ///
253
  ///By definition, a digraph is called \e Eulerian if
254
  ///and only if it is connected and the number of incoming and outgoing
248 255
  ///arcs are the same for each node.
249 256
  ///Similarly, an undirected graph is called \e Eulerian if
250
  ///and only if it is connected and the number of incident arcs is even
251
  ///for each node. <em>Therefore, there are digraphs which are not Eulerian,
252
  ///but still have an Euler tour</em>.
257
  ///and only if it is connected and the number of incident edges is even
258
  ///for each node.
259
  ///
260
  ///\note There are (di)graphs that are not Eulerian, but still have an
261
  /// Euler tour, since they may contain isolated nodes.
262
  ///
263
  ///\sa DiEulerIt, EulerIt
253 264
  template<typename GR>
... ...
@@ -270,3 +281,3 @@
270 281
      if(countInArcs(g,n)!=countOutArcs(g,n)) return false;
271
    return connected(Undirector<const GR>(g));
282
    return connected(undirector(g));
272 283
  }
Show white space 6 line context
... ...
@@ -20,3 +20,4 @@
20 20
#include <lemon/list_graph.h>
21
#include <test/test_tools.h>
21
#include <lemon/adaptors.h>
22
#include "test_tools.h"
22 23

	
... ...
@@ -25,3 +26,4 @@
25 26
template <typename Digraph>
26
void checkDiEulerIt(const Digraph& g)
27
void checkDiEulerIt(const Digraph& g,
28
                    const typename Digraph::Node& start = INVALID)
27 29
{
... ...
@@ -29,12 +31,12 @@
29 31

	
30
  DiEulerIt<Digraph> e(g);
32
  DiEulerIt<Digraph> e(g, start);
33
  if (e == INVALID) return;
31 34
  typename Digraph::Node firstNode = g.source(e);
32 35
  typename Digraph::Node lastNode = g.target(e);
36
  if (start != INVALID) {
37
    check(firstNode == start, "checkDiEulerIt: Wrong first node");
38
  }
33 39

	
34
  for (; e != INVALID; ++e)
35
  {
36
    if (e != INVALID)
37
    {
38
      lastNode = g.target(e);
39
    }
40
  for (; e != INVALID; ++e) {
41
    if (e != INVALID) lastNode = g.target(e);
40 42
    ++visitationNumber[e];
... ...
@@ -43,3 +45,3 @@
43 45
  check(firstNode == lastNode,
44
      "checkDiEulerIt: first and last node are not the same");
46
      "checkDiEulerIt: First and last nodes are not the same");
45 47

	
... ...
@@ -48,3 +50,3 @@
48 50
    check(visitationNumber[a] == 1,
49
        "checkDiEulerIt: not visited or multiple times visited arc found");
51
        "checkDiEulerIt: Not visited or multiple times visited arc found");
50 52
  }
... ...
@@ -53,3 +55,4 @@
53 55
template <typename Graph>
54
void checkEulerIt(const Graph& g)
56
void checkEulerIt(const Graph& g,
57
                  const typename Graph::Node& start = INVALID)
55 58
{
... ...
@@ -57,12 +60,12 @@
57 60

	
58
  EulerIt<Graph> e(g);
59
  typename Graph::Node firstNode = g.u(e);
60
  typename Graph::Node lastNode = g.v(e);
61
  EulerIt<Graph> e(g, start);
62
  if (e == INVALID) return;
63
  typename Graph::Node firstNode = g.source(typename Graph::Arc(e));
64
  typename Graph::Node lastNode = g.target(typename Graph::Arc(e));
65
  if (start != INVALID) {
66
    check(firstNode == start, "checkEulerIt: Wrong first node");
67
  }
61 68

	
62
  for (; e != INVALID; ++e)
63
  {
64
    if (e != INVALID)
65
    {
66
      lastNode = g.v(e);
67
    }
69
  for (; e != INVALID; ++e) {
70
    if (e != INVALID) lastNode = g.target(typename Graph::Arc(e));
68 71
    ++visitationNumber[e];
... ...
@@ -71,3 +74,3 @@
71 74
  check(firstNode == lastNode,
72
      "checkEulerIt: first and last node are not the same");
75
      "checkEulerIt: First and last nodes are not the same");
73 76

	
... ...
@@ -76,3 +79,3 @@
76 79
    check(visitationNumber[e] == 1,
77
        "checkEulerIt: not visited or multiple times visited edge found");
80
        "checkEulerIt: Not visited or multiple times visited edge found");
78 81
  }
... ...
@@ -83,70 +86,137 @@
83 86
  typedef ListDigraph Digraph;
84
  typedef ListGraph Graph;
87
  typedef Undirector<Digraph> Graph;
88
  
89
  {
90
    Digraph d;
91
    Graph g(d);
92
    
93
    checkDiEulerIt(d);
94
    checkDiEulerIt(g);
95
    checkEulerIt(g);
85 96

	
86
  Digraph digraphWithEulerianCircuit;
97
    check(eulerian(d), "This graph is Eulerian");
98
    check(eulerian(g), "This graph is Eulerian");
99
  }
87 100
  {
88
    Digraph& g = digraphWithEulerianCircuit;
101
    Digraph d;
102
    Graph g(d);
103
    Digraph::Node n = d.addNode();
89 104

	
90
    Digraph::Node n0 = g.addNode();
91
    Digraph::Node n1 = g.addNode();
92
    Digraph::Node n2 = g.addNode();
105
    checkDiEulerIt(d);
106
    checkDiEulerIt(g);
107
    checkEulerIt(g);
93 108

	
94
    g.addArc(n0, n1);
95
    g.addArc(n1, n0);
96
    g.addArc(n1, n2);
97
    g.addArc(n2, n1);
109
    check(eulerian(d), "This graph is Eulerian");
110
    check(eulerian(g), "This graph is Eulerian");
98 111
  }
112
  {
113
    Digraph d;
114
    Graph g(d);
115
    Digraph::Node n = d.addNode();
116
    d.addArc(n, n);
99 117

	
100
  Digraph digraphWithoutEulerianCircuit;
118
    checkDiEulerIt(d);
119
    checkDiEulerIt(g);
120
    checkEulerIt(g);
121

	
122
    check(eulerian(d), "This graph is Eulerian");
123
    check(eulerian(g), "This graph is Eulerian");
124
  }
101 125
  {
102
    Digraph& g = digraphWithoutEulerianCircuit;
126
    Digraph d;
127
    Graph g(d);
128
    Digraph::Node n1 = d.addNode();
129
    Digraph::Node n2 = d.addNode();
130
    Digraph::Node n3 = d.addNode();
131
    
132
    d.addArc(n1, n2);
133
    d.addArc(n2, n1);
134
    d.addArc(n2, n3);
135
    d.addArc(n3, n2);
103 136

	
104
    Digraph::Node n0 = g.addNode();
105
    Digraph::Node n1 = g.addNode();
106
    Digraph::Node n2 = g.addNode();
137
    checkDiEulerIt(d);
138
    checkDiEulerIt(d, n2);
139
    checkDiEulerIt(g);
140
    checkDiEulerIt(g, n2);
141
    checkEulerIt(g);
142
    checkEulerIt(g, n2);
107 143

	
108
    g.addArc(n0, n1);
109
    g.addArc(n1, n0);
110
    g.addArc(n1, n2);
144
    check(eulerian(d), "This graph is Eulerian");
145
    check(eulerian(g), "This graph is Eulerian");
111 146
  }
147
  {
148
    Digraph d;
149
    Graph g(d);
150
    Digraph::Node n1 = d.addNode();
151
    Digraph::Node n2 = d.addNode();
152
    Digraph::Node n3 = d.addNode();
153
    Digraph::Node n4 = d.addNode();
154
    Digraph::Node n5 = d.addNode();
155
    Digraph::Node n6 = d.addNode();
156
    
157
    d.addArc(n1, n2);
158
    d.addArc(n2, n4);
159
    d.addArc(n1, n3);
160
    d.addArc(n3, n4);
161
    d.addArc(n4, n1);
162
    d.addArc(n3, n5);
163
    d.addArc(n5, n2);
164
    d.addArc(n4, n6);
165
    d.addArc(n2, n6);
166
    d.addArc(n6, n1);
167
    d.addArc(n6, n3);
112 168

	
113
  Graph graphWithEulerianCircuit;
169
    checkDiEulerIt(d);
170
    checkDiEulerIt(d, n1);
171
    checkDiEulerIt(d, n5);
172

	
173
    checkDiEulerIt(g);
174
    checkDiEulerIt(g, n1);
175
    checkDiEulerIt(g, n5);
176
    checkEulerIt(g);
177
    checkEulerIt(g, n1);
178
    checkEulerIt(g, n5);
179

	
180
    check(eulerian(d), "This graph is Eulerian");
181
    check(eulerian(g), "This graph is Eulerian");
182
  }
114 183
  {
115
    Graph& g = graphWithEulerianCircuit;
184
    Digraph d;
185
    Graph g(d);
186
    Digraph::Node n0 = d.addNode();
187
    Digraph::Node n1 = d.addNode();
188
    Digraph::Node n2 = d.addNode();
189
    Digraph::Node n3 = d.addNode();
190
    Digraph::Node n4 = d.addNode();
191
    Digraph::Node n5 = d.addNode();
192
    
193
    d.addArc(n1, n2);
194
    d.addArc(n2, n3);
195
    d.addArc(n3, n1);
116 196

	
117
    Graph::Node n0 = g.addNode();
118
    Graph::Node n1 = g.addNode();
119
    Graph::Node n2 = g.addNode();
197
    checkDiEulerIt(d);
198
    checkDiEulerIt(d, n2);
120 199

	
121
    g.addEdge(n0, n1);
122
    g.addEdge(n1, n2);
123
    g.addEdge(n2, n0);
200
    checkDiEulerIt(g);
201
    checkDiEulerIt(g, n2);
202
    checkEulerIt(g);
203
    checkEulerIt(g, n2);
204

	
205
    check(!eulerian(d), "This graph is not Eulerian");
206
    check(!eulerian(g), "This graph is not Eulerian");
124 207
  }
208
  {
209
    Digraph d;
210
    Graph g(d);
211
    Digraph::Node n1 = d.addNode();
212
    Digraph::Node n2 = d.addNode();
213
    Digraph::Node n3 = d.addNode();
214
    
215
    d.addArc(n1, n2);
216
    d.addArc(n2, n3);
125 217

	
126
  Graph graphWithoutEulerianCircuit;
127
  {
128
    Graph& g = graphWithoutEulerianCircuit;
129

	
130
    Graph::Node n0 = g.addNode();
131
    Graph::Node n1 = g.addNode();
132
    Graph::Node n2 = g.addNode();
133

	
134
    g.addEdge(n0, n1);
135
    g.addEdge(n1, n2);
218
    check(!eulerian(d), "This graph is not Eulerian");
219
    check(!eulerian(g), "This graph is not Eulerian");
136 220
  }
137 221

	
138
  checkDiEulerIt(digraphWithEulerianCircuit);
139

	
140
  checkEulerIt(graphWithEulerianCircuit);
141

	
142
  check(eulerian(digraphWithEulerianCircuit),
143
      "this graph should have an Eulerian circuit");
144
  check(!eulerian(digraphWithoutEulerianCircuit),
145
      "this graph should not have an Eulerian circuit");
146

	
147
  check(eulerian(graphWithEulerianCircuit),
148
      "this graph should have an Eulerian circuit");
149
  check(!eulerian(graphWithoutEulerianCircuit),
150
      "this graph should have an Eulerian circuit");
151

	
152 222
  return 0;
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