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
|
package de.lmu.ifi.dbs.elki.utilities.datastructures.heap;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2015
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.Arrays;
import de.lmu.ifi.dbs.elki.math.MathUtil;
/**
* Binary heap for primitive types.
*
* @author Erich Schubert
*
* @apiviz.has UnsortedIter
*/
public class IntegerMinHeap implements IntegerHeap {
/**
* Base heap.
*/
protected int[] twoheap;
/**
* Current size of heap.
*/
protected int size;
/**
* Initial size of the 2-ary heap.
*/
private final static int TWO_HEAP_INITIAL_SIZE = (1 << 5) - 1;
/**
* Constructor, with default size.
*/
public IntegerMinHeap() {
super();
int[] twoheap = new int[TWO_HEAP_INITIAL_SIZE];
this.twoheap = twoheap;
}
/**
* Constructor, with given minimum size.
*
* @param minsize Minimum size
*/
public IntegerMinHeap(int minsize) {
super();
final int size = MathUtil.nextPow2Int(minsize + 1) - 1;
int[] twoheap = new int[size];
this.twoheap = twoheap;
}
@Override
public void clear() {
size = 0;
Arrays.fill(twoheap, 0);
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return (size == 0);
}
@Override
public void add(int o) {
final int co = o;
// System.err.println("Add: " + o);
if (size >= twoheap.length) {
// Grow by one layer.
twoheap = Arrays.copyOf(twoheap, twoheap.length + twoheap.length + 1);
}
final int twopos = size;
twoheap[twopos] = co;
++size;
heapifyUp(twopos, co);
}
@Override
public void add(int key, int max) {
if (size < max) {
add(key);
} else if (twoheap[0] < key) {
replaceTopElement(key);
}
}
@Override
public int replaceTopElement(int reinsert) {
final int ret = twoheap[0];
heapifyDown( reinsert);
return ret;
}
/**
* Heapify-Up method for 2-ary heap.
*
* @param twopos Position in 2-ary heap.
* @param cur Current object
*/
private void heapifyUp(int twopos, int cur) {
while (twopos > 0) {
final int parent = (twopos - 1) >>> 1;
int par = twoheap[parent];
if (cur >= par) {
break;
}
twoheap[twopos] = par;
twopos = parent;
}
twoheap[twopos] = cur;
}
@Override
public int poll() {
final int ret = twoheap[0];
--size;
// Replacement object:
if (size > 0) {
final int reinsert = twoheap[size];
twoheap[size] = 0;
heapifyDown(reinsert);
} else {
twoheap[0] = 0;
}
return ret;
}
/**
* Invoke heapify-down for the root object.
*
* @param cur Object to insert.
*/
private void heapifyDown(int cur) {
final int stop = size >>> 1;
int twopos = 0;
while (twopos < stop) {
int bestchild = (twopos << 1) + 1;
int best = twoheap[bestchild];
final int right = bestchild + 1;
if (right < size && best > twoheap[right]) {
bestchild = right;
best = twoheap[right];
}
if (cur <= best) {
break;
}
twoheap[twopos] = best;
twopos = bestchild;
}
twoheap[twopos] = cur;
}
@Override
public int peek() {
return twoheap[0];
}
@Override
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append(IntegerMinHeap.class.getSimpleName()).append(" [");
for (UnsortedIter iter = new UnsortedIter(); iter.valid(); iter.advance()) {
buf.append(iter.get()).append(',');
}
buf.append(']');
return buf.toString();
}
@Override
public UnsortedIter unsortedIter() {
return new UnsortedIter();
}
/**
* Unsorted iterator - in heap order. Does not poll the heap.
*
* Use this class as follows:
*
* <pre>
* {@code
* for (IntegerHeap.UnsortedIter iter = heap.unsortedIter(); iter.valid(); iter.next()) {
* doSomething(iter.get());
* }
* }
* </pre>
*
* @author Erich Schubert
*/
private class UnsortedIter implements IntegerHeap.UnsortedIter {
/**
* Iterator position.
*/
protected int pos = 0;
@Override
public boolean valid() {
return pos < size;
}
@Override
public de.lmu.ifi.dbs.elki.utilities.datastructures.iterator.Iter advance() {
pos++;
return this;
}
@Override
public int get() {
return twoheap[pos];
}
}
}
|
