File: IndexedPriorityQueueBinaryHeapPair.h

package info (click to toggle)
cain 1.10+dfsg-2
  • links: PTS, VCS
  • area: main
  • in suites: stretch
  • size: 29,856 kB
  • sloc: cpp: 49,612; python: 14,988; xml: 11,654; ansic: 3,644; makefile: 133; sh: 2
file content (399 lines) | stat: -rw-r--r-- 9,445 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
// -*- C++ -*-

/*!
  \file ads/indexedPriorityQueue/IndexedPriorityQueueBinaryHeapPair.h
  \brief Indexed priority queue that partitions the active and inactive elements.
*/

#if !defined(__ads_indexedPriorityQueue_IndexedPriorityQueueBinaryHeapPair_h__)
#define __ads_indexedPriorityQueue_IndexedPriorityQueueBinaryHeapPair_h__

#include "IndexedPriorityQueueBase.h"
#include <stddef.h>

#include <cstddef>

namespace ads {

//! Indexed priority queue that partitions the active and inactive elements.
/*!
  \param Key is the key type.
*/
template < typename _Key = double >
class IndexedPriorityQueueBinaryHeapPair {
   //
   // Enumerations.
   //
public:

   enum {UsesPropensities = false};

   //
   // Public types.
   //
public:

   //! The key type.
   typedef _Key Key;

   //
   // Private types.
   //
private:

   typedef std::pair<int, Key> Value;
   typedef std::vector<Value> Queue;
   typedef typename Queue::const_iterator ConstIterator;
   typedef typename Queue::iterator Iterator;

   //
   // Nested classes.
   //
private:

   //! Compare two queue elements.
   struct Compare {
      bool
      operator()(const Value& x, const Value& y) const {
         return x.second < y.second;
      }
   };

   //
   // Member data.
   //
private:

   Queue _queue;
   std::vector<Iterator> _pointers;
   Iterator _heapEnd;
   Compare _compare;

   //--------------------------------------------------------------------------
   //! \name Constructors etc.
   //@{
public:

   //! Construct from the size.
   IndexedPriorityQueueBinaryHeapPair(const std::size_t size) :
      _queue(size),
      _pointers(size),
      _heapEnd(_queue.begin()) {
      clear();
   }

   //@}
   //--------------------------------------------------------------------------
   //! \name Accessors.
   //@{
public:

   //! Return the key of the specified element.
   Key
   get(const int index) const {
      return _pointers[index]->second;
   }

   //! Return true if the binary heap data struture is valid.
   bool
   isValid() const {
      const std::size_t size = _heapEnd - _queue.begin();
      std::size_t parent = 0;
      for (std::size_t child = 1; child < size; ++child) {
         if (_compare(_queue[child], _queue[parent])) {
            return false;
         }
         if ((child & 1) == 0) {
            ++parent;
         }
      }
      return true;
   }

private:

   //! Return the beginning of the queue.
   ConstIterator
   getQueueBeginning() const {
      return _queue.begin();
   }

   //! Return the end of the queue.
   ConstIterator
   getQueueEnd() const {
      return _heapEnd;
   }

   //@}
   //--------------------------------------------------------------------------
   //! \name Manipulators.
   //@{
public:

   //! Return the index of the top element.
   int
   top() {
#ifdef DEBUG_stlib
      assert(! _queue.empty());
#endif
      return _queue.begin()->first;
   }

   //! Pop the top element off the queue.
   void
   popTop() {
#ifdef DEBUG_stlib
      assert(_queue.begin()->second != std::numeric_limits<Key>::max());
#endif
      _queue.begin()->second = std::numeric_limits<Key>::max();
      remove(0);
#ifdef DEBUG_stlib
      assert(isValid());
#endif
   }

   //! Pop the element off the queue.
   void
   pop(const int index) {
#ifdef DEBUG_stlib
      assert(isValid());
#endif
#ifdef DEBUG_stlib
      // It must be in the active queue.
      assert(_pointers[index]->second != std::numeric_limits<Key>::max());
#endif
      _pointers[index]->second = std::numeric_limits<Key>::max();
      remove(_pointers[index] - _queue.begin());
#ifdef DEBUG_stlib
      assert(isValid());
#endif
   }

   //! Push the value into the queue.
   void
   push(const int index, const Key key) {
#ifdef DEBUG_stlib
      assert(_pointers[index]->second == std::numeric_limits<Key>::max() &&
             key != std::numeric_limits<Key>::max());
#endif
      _pointers[index]->second = key;
      insert(index);
#ifdef DEBUG_stlib
      assert(isValid());
#endif
   }

   //! Push the value at the top into the queue.
   void
   pushTop(const Key key) {
#ifdef DEBUG_stlib
      assert(key != std::numeric_limits<Key>::max());
#endif
      _queue[0].second = key;
#ifdef GIBSON_BRUCK_UPDATE
      updateRecursive(0);
#else
      pushDown(0);
#endif
#ifdef DEBUG_stlib
      assert(isValid());
#endif
   }

   //! Change the value in the queue.
   void
   set(const int index, const Key key) {
#ifdef DEBUG_stlib
      assert(_pointers[index]->second != std::numeric_limits<Key>::max() &&
             key != std::numeric_limits<Key>::max());
#endif
      // If we are using the Gibson and Bruck updating algorithm.
#ifdef GIBSON_BRUCK_UPDATE
      _pointers[index]->second = key;
      updateRecursive(_pointers[index] - getQueueBeginning());
#else
      if (key < _pointers[index]->second) {
         _pointers[index]->second = key;
         pushUp(_pointers[index] - getQueueBeginning());
      }
      else {
         _pointers[index]->second = key;
         pushDown(_pointers[index] - getQueueBeginning());
      }
#endif
#ifdef DEBUG_stlib
      assert(isValid());
#endif
   }

   //! Clear the queue.
   void
   clear() {
      for (std::size_t i = 0; i != _queue.size(); ++i) {
         _queue[i].first = i;
         _queue[i].second = std::numeric_limits<Key>::max();
      }
      for (std::size_t i = 0; i != _queue.size(); ++i) {
         _pointers[i] = _queue.begin() + i;
      }
      _heapEnd = _queue.begin();
   }

   //! Shift the keys by the specified amount.
   void
   shift(const Key x) {
      for (std::size_t i = 0; i != _queue.size(); ++i) {
         _queue[i].second += x;
      }
   }

private:

   //! Return the beginning of the queue.
   Iterator
   getQueueBeginning() {
      return _queue.begin();
   }

   //! Return the end of the queue.
   Iterator
   getQueueEnd() {
      return _heapEnd;
   }

   //! Remove the element from the heap.
   /*!
     \pre The element must be in the heap.
   */
   void
   remove(const int n) {
#ifdef DEBUG_stlib
      assert(n < _heapEnd - getQueueBeginning());
#endif
      --_heapEnd;
      swap(_queue.begin() + n, _heapEnd);
#ifdef GIBSON_BRUCK_UPDATE
      updateRecursive(n);
#else
      pushUpOrDown(n);
#endif
   }

   //! Insert the element in the heap.
   /*!
     \pre The element must not be in the heap.
   */
   void
   insert(const int index) {
#ifdef DEBUG_stlib
      assert(_pointers[index] >= _heapEnd);
#endif
      swap(_pointers[index], _heapEnd);
#ifdef GIBSON_BRUCK_UPDATE
      updateRecursive(_heapEnd - getQueueBeginning());
#else
      pushUp(_heapEnd - getQueueBeginning());
#endif
      ++_heapEnd;
   }

   void
   pushUp(ptrdiff_t child) {
      ptrdiff_t parent = (child - 1) / 2;
      while (child > 0 && _compare(_queue[child], _queue[parent])) {
         swap(getQueueBeginning() + child, getQueueBeginning() + parent);
         child = parent;
         parent = (child - 1) / 2;
      }
   }

   void
   pushDown(ptrdiff_t parent) {
      ptrdiff_t child = getSmallerChild(parent);
      while (child != 0 && _compare(_queue[child], _queue[parent])) {
         swap(getQueueBeginning() + child, getQueueBeginning() + parent);
         parent = child;
         child = getSmallerChild(parent);
      }
   }

   //! The Gibson and Bruck updating algorithm.
   void
   updateRecursive(ptrdiff_t n) {
      ptrdiff_t parent = (n - 1) / 2;
      if (n > 0 && _compare(_queue[n], _queue[parent])) {
         swap(getQueueBeginning() + n, getQueueBeginning() + parent);
         updateRecursive(parent);
      }
      else {
         ptrdiff_t child = getSmallerChild(n);
         if (child != 0 && _compare(_queue[child], _queue[n])) {
            swap(getQueueBeginning() + child, getQueueBeginning() + n);
            updateRecursive(child);
         }
      }
   }

   //! Update the position.
   void
   update(ptrdiff_t n) {
      while (true) {
         ptrdiff_t parent = (n - 1) / 2;
         if (n > 0 && _compare(_queue[n], _queue[parent])) {
            swap(getQueueBeginning() + n, getQueueBeginning() + parent);
            n = parent;
            continue;
         }
         else {
            ptrdiff_t child = getSmallerChild(n);
            if (child != 0 && _compare(_queue[child], _queue[n])) {
               swap(getQueueBeginning() + child, getQueueBeginning() + n);
               n = child;
               continue;
            }
         }
         break;
      }
   }

   //! Update the position. This is faster than update().
   void
   pushUpOrDown(ptrdiff_t n) {
      ptrdiff_t parent = (n - 1) / 2;
      if (n > 0 && _compare(_queue[n], _queue[parent])) {
         pushUp(n);
      }
      else {
         pushDown(n);
      }
   }

   //! Return the index of the smaller child or 0 if there are no children.
   ptrdiff_t
   getSmallerChild(ptrdiff_t parent) const {
      const ptrdiff_t size = getQueueEnd() - getQueueBeginning();
      ptrdiff_t child = 2 * parent + 1;
      // If there are no children.
      if (child >= size) {
         return 0;
      }
      // If the second child is smaller.
      if (child + 1 < size && _compare(_queue[child + 1], _queue[child])) {
         ++child;
      }
      return child;
   }

   //! Swap the two elements' positions in the queue.
   void
   swap(const Iterator i, const Iterator j) {
      std::swap(_pointers[i->first], _pointers[j->first]);
      std::swap(*i, *j);
   }

   //@}
};

} // namespace ads

#endif