68 |
|
private static final int DEFAULT_INITIAL_CAPACITY = 11; |
69 |
|
|
70 |
|
/** |
71 |
< |
* Priority queue represented as a balanced binary heap: the two children |
72 |
< |
* of queue[n] are queue[2*n] and queue[2*n + 1]. The priority queue is |
73 |
< |
* ordered by comparator, or by the elements' natural ordering, if |
74 |
< |
* comparator is null: For each node n in the heap and each descendant d |
75 |
< |
* of n, n <= d. |
76 |
< |
* |
77 |
< |
* The element with the lowest value is in queue[1], assuming the queue is |
78 |
< |
* nonempty. (A one-based array is used in preference to the traditional |
79 |
< |
* zero-based array to simplify parent and child calculations.) |
80 |
< |
* |
81 |
< |
* queue.length must be >= 2, even if size == 0. |
71 |
> |
* Priority queue represented as a balanced binary heap: the two |
72 |
> |
* children of queue[n] are queue[2*n+1] and queue[2*(n+1)]. The |
73 |
> |
* priority queue is ordered by comparator, or by the elements' |
74 |
> |
* natural ordering, if comparator is null: For each node n in the |
75 |
> |
* heap and each descendant d of n, n <= d. The element with the |
76 |
> |
* lowest value is in queue[0], assuming the queue is nonempty. |
77 |
|
*/ |
78 |
|
private transient Object[] queue; |
79 |
|
|
129 |
|
*/ |
130 |
|
public PriorityQueue(int initialCapacity, |
131 |
|
Comparator<? super E> comparator) { |
132 |
+ |
// Note: This restriction of at least one is not actually needed, |
133 |
+ |
// but continues for 1.5 compatibility |
134 |
|
if (initialCapacity < 1) |
135 |
|
throw new IllegalArgumentException(); |
136 |
< |
this.queue = new Object[initialCapacity + 1]; |
136 |
> |
this.queue = new Object[initialCapacity]; |
137 |
|
this.comparator = comparator; |
138 |
|
} |
139 |
|
|
140 |
|
/** |
144 |
– |
* Common code to initialize underlying queue array across |
145 |
– |
* constructors below. |
146 |
– |
*/ |
147 |
– |
private void initializeArray(Collection<? extends E> c) { |
148 |
– |
int sz = c.size(); |
149 |
– |
int initialCapacity = (int)Math.min((sz * 110L) / 100, |
150 |
– |
Integer.MAX_VALUE - 1); |
151 |
– |
if (initialCapacity < 1) |
152 |
– |
initialCapacity = 1; |
153 |
– |
|
154 |
– |
this.queue = new Object[initialCapacity + 1]; |
155 |
– |
} |
156 |
– |
|
157 |
– |
/** |
158 |
– |
* Initially fill elements of the queue array under the |
159 |
– |
* knowledge that it is sorted or is another PQ, in which |
160 |
– |
* case we can just place the elements in the order presented. |
161 |
– |
*/ |
162 |
– |
private void fillFromSorted(Collection<? extends E> c) { |
163 |
– |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
164 |
– |
int k = ++size; |
165 |
– |
if (k >= queue.length) |
166 |
– |
grow(k); |
167 |
– |
queue[k] = i.next(); |
168 |
– |
} |
169 |
– |
} |
170 |
– |
|
171 |
– |
/** |
172 |
– |
* Initially fill elements of the queue array that is not to our knowledge |
173 |
– |
* sorted, so we must rearrange the elements to guarantee the heap |
174 |
– |
* invariant. |
175 |
– |
*/ |
176 |
– |
private void fillFromUnsorted(Collection<? extends E> c) { |
177 |
– |
for (Iterator<? extends E> i = c.iterator(); i.hasNext(); ) { |
178 |
– |
int k = ++size; |
179 |
– |
if (k >= queue.length) |
180 |
– |
grow(k); |
181 |
– |
queue[k] = i.next(); |
182 |
– |
} |
183 |
– |
heapify(); |
184 |
– |
} |
185 |
– |
|
186 |
– |
/** |
141 |
|
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
142 |
< |
* specified collection. The priority queue has an initial |
189 |
< |
* capacity of 110% of the size of the specified collection or 1 |
190 |
< |
* if the collection is empty. If the specified collection is an |
142 |
> |
* specified collection. If the specified collection is an |
143 |
|
* instance of a {@link java.util.SortedSet} or is another |
144 |
|
* <tt>PriorityQueue</tt>, the priority queue will be ordered |
145 |
|
* according to the same ordering. Otherwise, this priority queue |
154 |
|
* of its elements are null |
155 |
|
*/ |
156 |
|
public PriorityQueue(Collection<? extends E> c) { |
157 |
< |
initializeArray(c); |
158 |
< |
if (c instanceof SortedSet) { |
159 |
< |
SortedSet<? extends E> s = (SortedSet<? extends E>)c; |
160 |
< |
comparator = (Comparator<? super E>)s.comparator(); |
161 |
< |
fillFromSorted(s); |
162 |
< |
} else if (c instanceof PriorityQueue) { |
163 |
< |
PriorityQueue<? extends E> s = (PriorityQueue<? extends E>) c; |
164 |
< |
comparator = (Comparator<? super E>)s.comparator(); |
213 |
< |
fillFromSorted(s); |
214 |
< |
} else { |
157 |
> |
initFromCollection(c); |
158 |
> |
if (c instanceof SortedSet) |
159 |
> |
comparator = (Comparator<? super E>) |
160 |
> |
((SortedSet<? extends E>)c).comparator(); |
161 |
> |
else if (c instanceof PriorityQueue) |
162 |
> |
comparator = (Comparator<? super E>) |
163 |
> |
((PriorityQueue<? extends E>)c).comparator(); |
164 |
> |
else { |
165 |
|
comparator = null; |
166 |
< |
fillFromUnsorted(c); |
166 |
> |
heapify(); |
167 |
|
} |
168 |
|
} |
169 |
|
|
170 |
|
/** |
171 |
|
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
172 |
< |
* specified priority queue. The priority queue has an initial |
223 |
< |
* capacity of 110% of the size of the specified priority queue or |
224 |
< |
* 1 if the priority queue is empty. This priority queue will be |
172 |
> |
* specified priority queue. This priority queue will be |
173 |
|
* ordered according to the same ordering as the given priority |
174 |
|
* queue. |
175 |
|
* |
182 |
|
* of its elements are null |
183 |
|
*/ |
184 |
|
public PriorityQueue(PriorityQueue<? extends E> c) { |
237 |
– |
initializeArray(c); |
185 |
|
comparator = (Comparator<? super E>)c.comparator(); |
186 |
< |
fillFromSorted(c); |
186 |
> |
initFromCollection(c); |
187 |
|
} |
188 |
|
|
189 |
|
/** |
190 |
|
* Creates a <tt>PriorityQueue</tt> containing the elements in the |
191 |
< |
* specified sorted set. The priority queue has an initial |
245 |
< |
* capacity of 110% of the size of the specified sorted set or 1 |
246 |
< |
* if the sorted set is empty. This priority queue will be ordered |
191 |
> |
* specified sorted set. This priority queue will be ordered |
192 |
|
* according to the same ordering as the given sorted set. |
193 |
|
* |
194 |
|
* @param c the sorted set whose elements are to be placed |
200 |
|
* of its elements are null |
201 |
|
*/ |
202 |
|
public PriorityQueue(SortedSet<? extends E> c) { |
258 |
– |
initializeArray(c); |
203 |
|
comparator = (Comparator<? super E>)c.comparator(); |
204 |
< |
fillFromSorted(c); |
204 |
> |
initFromCollection(c); |
205 |
|
} |
206 |
|
|
207 |
|
/** |
208 |
< |
* Resize array, if necessary, to be able to hold given index. |
208 |
> |
* Initialize queue array with elements from the given Collection. |
209 |
> |
* @param c the collection |
210 |
|
*/ |
211 |
< |
private void grow(int index) { |
212 |
< |
int newlen = queue.length; |
213 |
< |
if (index < newlen) // don't need to grow |
214 |
< |
return; |
215 |
< |
if (index == Integer.MAX_VALUE) |
211 |
> |
private void initFromCollection(Collection<? extends E> c) { |
212 |
> |
Object[] a = c.toArray(); |
213 |
> |
// If c.toArray incorrectly doesn't return Object[], copy it. |
214 |
> |
if (a.getClass() != Object[].class) |
215 |
> |
a = Arrays.copyOf(a, a.length, Object[].class); |
216 |
> |
queue = a; |
217 |
> |
size = a.length; |
218 |
> |
} |
219 |
> |
|
220 |
> |
/** |
221 |
> |
* Increases the capacity of the array. |
222 |
> |
* |
223 |
> |
* @param minCapacity the desired minimum capacity |
224 |
> |
*/ |
225 |
> |
private void grow(int minCapacity) { |
226 |
> |
if (minCapacity < 0) // overflow |
227 |
|
throw new OutOfMemoryError(); |
228 |
< |
while (newlen <= index) { |
229 |
< |
if (newlen >= Integer.MAX_VALUE / 2) // avoid overflow |
230 |
< |
newlen = Integer.MAX_VALUE; |
231 |
< |
else |
232 |
< |
newlen <<= 2; |
233 |
< |
} |
234 |
< |
queue = Arrays.copyOf(queue, newlen); |
228 |
> |
int oldCapacity = queue.length; |
229 |
> |
// Double size if small; else grow by 50% |
230 |
> |
int newCapacity = ((oldCapacity < 64)? |
231 |
> |
((oldCapacity + 1) * 2): |
232 |
> |
((oldCapacity * 3) / 2)); |
233 |
> |
if (newCapacity < minCapacity) |
234 |
> |
newCapacity = minCapacity; |
235 |
> |
queue = Arrays.copyOf(queue, newCapacity); |
236 |
|
} |
237 |
|
|
238 |
|
/** |
261 |
|
if (e == null) |
262 |
|
throw new NullPointerException(); |
263 |
|
modCount++; |
264 |
< |
++size; |
265 |
< |
|
266 |
< |
// Grow backing store if necessary |
267 |
< |
if (size >= queue.length) |
268 |
< |
grow(size); |
269 |
< |
|
270 |
< |
queue[size] = e; |
271 |
< |
fixUp(size); |
264 |
> |
int i = size; |
265 |
> |
if (i >= queue.length) |
266 |
> |
grow(i + 1); |
267 |
> |
size = i + 1; |
268 |
> |
if (i == 0) |
269 |
> |
queue[0] = e; |
270 |
> |
else |
271 |
> |
siftUp(i, e); |
272 |
|
return true; |
273 |
|
} |
274 |
|
|
275 |
|
public E peek() { |
276 |
|
if (size == 0) |
277 |
|
return null; |
278 |
< |
return (E) queue[1]; |
278 |
> |
return (E) queue[0]; |
279 |
|
} |
280 |
|
|
281 |
|
private int indexOf(Object o) { |
282 |
< |
if (o == null) |
283 |
< |
return -1; |
284 |
< |
for (int i = 1; i <= size; i++) |
285 |
< |
if (o.equals(queue[i])) |
286 |
< |
return i; |
282 |
> |
if (o != null) { |
283 |
> |
for (int i = 0; i < size; i++) |
284 |
> |
if (o.equals(queue[i])) |
285 |
> |
return i; |
286 |
> |
} |
287 |
|
return -1; |
288 |
|
} |
289 |
|
|
308 |
|
} |
309 |
|
|
310 |
|
/** |
311 |
+ |
* Version of remove using reference equality, not equals. |
312 |
+ |
* Needed by iterator.remove |
313 |
+ |
* |
314 |
+ |
* @param o element to be removed from this queue, if present |
315 |
+ |
* @return <tt>true</tt> if removed. |
316 |
+ |
*/ |
317 |
+ |
boolean removeEq(Object o) { |
318 |
+ |
for (int i = 0; i < size; i++) { |
319 |
+ |
if (o == queue[i]) { |
320 |
+ |
removeAt(i); |
321 |
+ |
return true; |
322 |
+ |
} |
323 |
+ |
} |
324 |
+ |
return false; |
325 |
+ |
} |
326 |
+ |
|
327 |
+ |
/** |
328 |
|
* Returns <tt>true</tt> if this queue contains the specified element. |
329 |
|
* More formally, returns <tt>true</tt> if and only if this queue contains |
330 |
|
* at least one element <tt>e</tt> such that <tt>o.equals(e)</tt>. |
347 |
|
* @return an array containing all of the elements in this queue. |
348 |
|
*/ |
349 |
|
public Object[] toArray() { |
350 |
< |
return Arrays.copyOfRange(queue, 1, size+1); |
350 |
> |
return Arrays.copyOf(queue, size); |
351 |
|
} |
352 |
|
|
353 |
|
/** |
377 |
|
public <T> T[] toArray(T[] a) { |
378 |
|
if (a.length < size) |
379 |
|
// Make a new array of a's runtime type, but my contents: |
380 |
< |
return (T[]) Arrays.copyOfRange(queue, 1, size+1, a.getClass()); |
381 |
< |
System.arraycopy(queue, 1, a, 0, size); |
380 |
> |
return (T[]) Arrays.copyOf(queue, size, a.getClass()); |
381 |
> |
System.arraycopy(queue, 0, a, 0, size); |
382 |
|
if (a.length > size) |
383 |
|
a[size] = null; |
384 |
|
return a; |
394 |
|
return new Itr(); |
395 |
|
} |
396 |
|
|
397 |
< |
private class Itr implements Iterator<E> { |
424 |
< |
|
397 |
> |
private final class Itr implements Iterator<E> { |
398 |
|
/** |
399 |
|
* Index (into queue array) of element to be returned by |
400 |
|
* subsequent call to next. |
401 |
|
*/ |
402 |
< |
private int cursor = 1; |
402 |
> |
private int cursor = 0; |
403 |
|
|
404 |
|
/** |
405 |
|
* Index of element returned by most recent call to next, |
406 |
|
* unless that element came from the forgetMeNot list. |
407 |
< |
* Reset to 0 if element is deleted by a call to remove. |
435 |
< |
*/ |
436 |
< |
private int lastRet = 0; |
437 |
< |
|
438 |
< |
/** |
439 |
< |
* The modCount value that the iterator believes that the backing |
440 |
< |
* List should have. If this expectation is violated, the iterator |
441 |
< |
* has detected concurrent modification. |
407 |
> |
* Set to -1 if element is deleted by a call to remove. |
408 |
|
*/ |
409 |
< |
private int expectedModCount = modCount; |
409 |
> |
private int lastRet = -1; |
410 |
|
|
411 |
|
/** |
412 |
< |
* A list of elements that were moved from the unvisited portion of |
412 |
> |
* A queue of elements that were moved from the unvisited portion of |
413 |
|
* the heap into the visited portion as a result of "unlucky" element |
414 |
|
* removals during the iteration. (Unlucky element removals are those |
415 |
< |
* that require a fixup instead of a fixdown.) We must visit all of |
415 |
> |
* that require a siftup instead of a siftdown.) We must visit all of |
416 |
|
* the elements in this list to complete the iteration. We do this |
417 |
|
* after we've completed the "normal" iteration. |
418 |
|
* |
419 |
|
* We expect that most iterations, even those involving removals, |
420 |
|
* will not use need to store elements in this field. |
421 |
|
*/ |
422 |
< |
private ArrayList<E> forgetMeNot = null; |
422 |
> |
private ArrayDeque<E> forgetMeNot = null; |
423 |
|
|
424 |
|
/** |
425 |
|
* Element returned by the most recent call to next iff that |
426 |
|
* element was drawn from the forgetMeNot list. |
427 |
|
*/ |
428 |
< |
private Object lastRetElt = null; |
428 |
> |
private E lastRetElt = null; |
429 |
> |
|
430 |
> |
/** |
431 |
> |
* The modCount value that the iterator believes that the backing |
432 |
> |
* List should have. If this expectation is violated, the iterator |
433 |
> |
* has detected concurrent modification. |
434 |
> |
*/ |
435 |
> |
private int expectedModCount = modCount; |
436 |
|
|
437 |
|
public boolean hasNext() { |
438 |
< |
return cursor <= size || forgetMeNot != null; |
438 |
> |
return cursor < size || |
439 |
> |
(forgetMeNot != null && !forgetMeNot.isEmpty()); |
440 |
|
} |
441 |
|
|
442 |
|
public E next() { |
443 |
< |
checkForComodification(); |
444 |
< |
E result; |
445 |
< |
if (cursor <= size) { |
446 |
< |
result = (E) queue[cursor]; |
447 |
< |
lastRet = cursor++; |
448 |
< |
} |
449 |
< |
else if (forgetMeNot == null) |
450 |
< |
throw new NoSuchElementException(); |
451 |
< |
else { |
478 |
< |
int remaining = forgetMeNot.size(); |
479 |
< |
result = forgetMeNot.remove(remaining - 1); |
480 |
< |
if (remaining == 1) |
481 |
< |
forgetMeNot = null; |
482 |
< |
lastRet = 0; |
483 |
< |
lastRetElt = result; |
443 |
> |
if (expectedModCount != modCount) |
444 |
> |
throw new ConcurrentModificationException(); |
445 |
> |
if (cursor < size) |
446 |
> |
return (E) queue[lastRet = cursor++]; |
447 |
> |
if (forgetMeNot != null) { |
448 |
> |
lastRet = -1; |
449 |
> |
lastRetElt = forgetMeNot.poll(); |
450 |
> |
if (lastRetElt != null) |
451 |
> |
return lastRetElt; |
452 |
|
} |
453 |
< |
return result; |
453 |
> |
throw new NoSuchElementException(); |
454 |
|
} |
455 |
|
|
456 |
|
public void remove() { |
457 |
< |
checkForComodification(); |
458 |
< |
|
459 |
< |
if (lastRet != 0) { |
457 |
> |
if (expectedModCount != modCount) |
458 |
> |
throw new ConcurrentModificationException(); |
459 |
> |
if (lastRet == -1 && lastRetElt == null) |
460 |
> |
throw new IllegalStateException(); |
461 |
> |
if (lastRet != -1) { |
462 |
|
E moved = PriorityQueue.this.removeAt(lastRet); |
463 |
< |
lastRet = 0; |
464 |
< |
if (moved == null) { |
463 |
> |
lastRet = -1; |
464 |
> |
if (moved == null) |
465 |
|
cursor--; |
466 |
< |
} else { |
466 |
> |
else { |
467 |
|
if (forgetMeNot == null) |
468 |
< |
forgetMeNot = new ArrayList<E>(); |
468 |
> |
forgetMeNot = new ArrayDeque<E>(); |
469 |
|
forgetMeNot.add(moved); |
470 |
|
} |
501 |
– |
} else if (lastRetElt != null) { |
502 |
– |
PriorityQueue.this.remove(lastRetElt); |
503 |
– |
lastRetElt = null; |
471 |
|
} else { |
472 |
< |
throw new IllegalStateException(); |
472 |
> |
PriorityQueue.this.removeEq(lastRetElt); |
473 |
> |
lastRetElt = null; |
474 |
|
} |
507 |
– |
|
475 |
|
expectedModCount = modCount; |
476 |
|
} |
477 |
|
|
511 |
– |
final void checkForComodification() { |
512 |
– |
if (modCount != expectedModCount) |
513 |
– |
throw new ConcurrentModificationException(); |
514 |
– |
} |
478 |
|
} |
479 |
|
|
480 |
|
public int size() { |
487 |
|
*/ |
488 |
|
public void clear() { |
489 |
|
modCount++; |
490 |
< |
|
528 |
< |
// Null out element references to prevent memory leak |
529 |
< |
for (int i=1; i<=size; i++) |
490 |
> |
for (int i = 0; i < size; i++) |
491 |
|
queue[i] = null; |
531 |
– |
|
492 |
|
size = 0; |
493 |
|
} |
494 |
|
|
495 |
|
public E poll() { |
496 |
|
if (size == 0) |
497 |
|
return null; |
498 |
+ |
int s = --size; |
499 |
|
modCount++; |
500 |
< |
|
501 |
< |
E result = (E) queue[1]; |
502 |
< |
queue[1] = queue[size]; |
503 |
< |
queue[size--] = null; // Drop extra ref to prevent memory leak |
504 |
< |
if (size > 1) |
544 |
< |
fixDown(1); |
545 |
< |
|
500 |
> |
E result = (E)queue[0]; |
501 |
> |
E x = (E)queue[s]; |
502 |
> |
queue[s] = null; |
503 |
> |
if (s != 0) |
504 |
> |
siftDown(0, x); |
505 |
|
return result; |
506 |
|
} |
507 |
|
|
508 |
|
/** |
509 |
< |
* Removes and returns the ith element from queue. (Recall that queue |
551 |
< |
* is one-based, so 1 <= i <= size.) |
509 |
> |
* Removes the ith element from queue. |
510 |
|
* |
511 |
< |
* Normally this method leaves the elements at positions from 1 up to i-1, |
512 |
< |
* inclusive, untouched. Under these circumstances, it returns null. |
513 |
< |
* Occasionally, in order to maintain the heap invariant, it must move |
514 |
< |
* the last element of the list to some index in the range [2, i-1], |
515 |
< |
* and move the element previously at position (i/2) to position i. |
516 |
< |
* Under these circumstances, this method returns the element that was |
517 |
< |
* previously at the end of the list and is now at some position between |
518 |
< |
* 2 and i-1 inclusive. |
511 |
> |
* Normally this method leaves the elements at up to i-1, |
512 |
> |
* inclusive, untouched. Under these circumstances, it returns |
513 |
> |
* null. Occasionally, in order to maintain the heap invariant, |
514 |
> |
* it must swap a later element of the list with one earlier than |
515 |
> |
* i. Under these circumstances, this method returns the element |
516 |
> |
* that was previously at the end of the list and is now at some |
517 |
> |
* position before i. This fact is used by iterator.remove so as to |
518 |
> |
* avoid missing traverseing elements. |
519 |
|
*/ |
520 |
|
private E removeAt(int i) { |
521 |
< |
assert i > 0 && i <= size; |
521 |
> |
assert i >= 0 && i < size; |
522 |
|
modCount++; |
523 |
< |
|
524 |
< |
E moved = (E) queue[size]; |
525 |
< |
queue[i] = moved; |
526 |
< |
queue[size--] = null; // Drop extra ref to prevent memory leak |
527 |
< |
if (i <= size) { |
528 |
< |
fixDown(i); |
523 |
> |
int s = --size; |
524 |
> |
if (s == i) // removed last element |
525 |
> |
queue[i] = null; |
526 |
> |
else { |
527 |
> |
E moved = (E) queue[s]; |
528 |
> |
queue[s] = null; |
529 |
> |
siftDown(i, moved); |
530 |
|
if (queue[i] == moved) { |
531 |
< |
fixUp(i); |
531 |
> |
siftUp(i, moved); |
532 |
|
if (queue[i] != moved) |
533 |
|
return moved; |
534 |
|
} |
537 |
|
} |
538 |
|
|
539 |
|
/** |
540 |
< |
* Establishes the heap invariant (described above) assuming the heap |
541 |
< |
* satisfies the invariant except possibly for the leaf-node indexed by k |
542 |
< |
* (which may have a nextExecutionTime less than its parent's). |
543 |
< |
* |
544 |
< |
* This method functions by "promoting" queue[k] up the hierarchy |
545 |
< |
* (by swapping it with its parent) repeatedly until queue[k] |
546 |
< |
* is greater than or equal to its parent. |
547 |
< |
*/ |
548 |
< |
private void fixUp(int k) { |
549 |
< |
if (comparator == null) { |
550 |
< |
while (k > 1) { |
551 |
< |
int j = k >> 1; |
552 |
< |
if (((Comparable<? super E>)queue[j]).compareTo((E)queue[k]) <= 0) |
553 |
< |
break; |
554 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
555 |
< |
k = j; |
556 |
< |
} |
557 |
< |
} else { |
558 |
< |
while (k > 1) { |
559 |
< |
int j = k >>> 1; |
560 |
< |
if (comparator.compare((E)queue[j], (E)queue[k]) <= 0) |
561 |
< |
break; |
562 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
563 |
< |
k = j; |
564 |
< |
} |
565 |
< |
} |
566 |
< |
} |
567 |
< |
|
568 |
< |
/** |
569 |
< |
* Establishes the heap invariant (described above) in the subtree |
570 |
< |
* rooted at k, which is assumed to satisfy the heap invariant except |
571 |
< |
* possibly for node k itself (which may be greater than its children). |
572 |
< |
* |
573 |
< |
* This method functions by "demoting" queue[k] down the hierarchy |
574 |
< |
* (by swapping it with its smaller child) repeatedly until queue[k] |
575 |
< |
* is less than or equal to its children. |
576 |
< |
*/ |
577 |
< |
private void fixDown(int k) { |
578 |
< |
int j; |
579 |
< |
if (comparator == null) { |
580 |
< |
while ((j = k << 1) <= size && (j > 0)) { |
581 |
< |
if (j<size && |
582 |
< |
((Comparable<? super E>)queue[j]).compareTo((E)queue[j+1]) > 0) |
583 |
< |
j++; // j indexes smallest kid |
584 |
< |
|
585 |
< |
if (((Comparable<? super E>)queue[k]).compareTo((E)queue[j]) <= 0) |
586 |
< |
break; |
587 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
588 |
< |
k = j; |
589 |
< |
} |
590 |
< |
} else { |
591 |
< |
while ((j = k << 1) <= size && (j > 0)) { |
592 |
< |
if (j<size && |
593 |
< |
comparator.compare((E)queue[j], (E)queue[j+1]) > 0) |
594 |
< |
j++; // j indexes smallest kid |
595 |
< |
if (comparator.compare((E)queue[k], (E)queue[j]) <= 0) |
596 |
< |
break; |
597 |
< |
Object tmp = queue[j]; queue[j] = queue[k]; queue[k] = tmp; |
598 |
< |
k = j; |
599 |
< |
} |
540 |
> |
* Inserts item x at position k, maintaining heap invariant by |
541 |
> |
* promoting x up the tree until it is greater than or equal to |
542 |
> |
* its parent, or is the root. |
543 |
> |
* |
544 |
> |
* To simplify and speed up coercions and comparisons. the |
545 |
> |
* Comparable and Comparator versions are separated into different |
546 |
> |
* methods that are otherwise identical. (Similarly for siftDown.) |
547 |
> |
* |
548 |
> |
* @param k the position to fill |
549 |
> |
* @param x the item to insert |
550 |
> |
*/ |
551 |
> |
private void siftUp(int k, E x) { |
552 |
> |
if (comparator != null) |
553 |
> |
siftUpUsingComparator(k, x); |
554 |
> |
else |
555 |
> |
siftUpComparable(k, x); |
556 |
> |
} |
557 |
> |
|
558 |
> |
private void siftUpComparable(int k, E x) { |
559 |
> |
Comparable<? super E> key = (Comparable<? super E>) x; |
560 |
> |
while (k > 0) { |
561 |
> |
int parent = (k - 1) >>> 1; |
562 |
> |
Object e = queue[parent]; |
563 |
> |
if (key.compareTo((E)e) >= 0) |
564 |
> |
break; |
565 |
> |
queue[k] = e; |
566 |
> |
k = parent; |
567 |
> |
} |
568 |
> |
queue[k] = key; |
569 |
> |
} |
570 |
> |
|
571 |
> |
private void siftUpUsingComparator(int k, E x) { |
572 |
> |
while (k > 0) { |
573 |
> |
int parent = (k - 1) >>> 1; |
574 |
> |
Object e = queue[parent]; |
575 |
> |
if (comparator.compare(x, (E)e) >= 0) |
576 |
> |
break; |
577 |
> |
queue[k] = e; |
578 |
> |
k = parent; |
579 |
> |
} |
580 |
> |
queue[k] = x; |
581 |
> |
} |
582 |
> |
|
583 |
> |
/** |
584 |
> |
* Inserts item x at position k, maintaining heap invariant by |
585 |
> |
* demoting x down the tree repeatedly until it is less than or |
586 |
> |
* equal to its children or is a leaf. |
587 |
> |
* |
588 |
> |
* @param k the position to fill |
589 |
> |
* @param x the item to insert |
590 |
> |
*/ |
591 |
> |
private void siftDown(int k, E x) { |
592 |
> |
if (comparator != null) |
593 |
> |
siftDownUsingComparator(k, x); |
594 |
> |
else |
595 |
> |
siftDownComparable(k, x); |
596 |
> |
} |
597 |
> |
|
598 |
> |
private void siftDownComparable(int k, E x) { |
599 |
> |
Comparable<? super E> key = (Comparable<? super E>)x; |
600 |
> |
int half = size >>> 1; // loop while a non-leaf |
601 |
> |
while (k < half) { |
602 |
> |
int child = (k << 1) + 1; // assume left child is least |
603 |
> |
Object c = queue[child]; |
604 |
> |
int right = child + 1; |
605 |
> |
if (right < size && |
606 |
> |
((Comparable<? super E>)c).compareTo((E)queue[right]) > 0) |
607 |
> |
c = queue[child = right]; |
608 |
> |
if (key.compareTo((E)c) <= 0) |
609 |
> |
break; |
610 |
> |
queue[k] = c; |
611 |
> |
k = child; |
612 |
> |
} |
613 |
> |
queue[k] = key; |
614 |
> |
} |
615 |
> |
|
616 |
> |
private void siftDownUsingComparator(int k, E x) { |
617 |
> |
int half = size >>> 1; |
618 |
> |
while (k < half) { |
619 |
> |
int child = (k << 1) + 1; |
620 |
> |
Object c = queue[child]; |
621 |
> |
int right = child + 1; |
622 |
> |
if (right < size && |
623 |
> |
comparator.compare((E)c, (E)queue[right]) > 0) |
624 |
> |
c = queue[child = right]; |
625 |
> |
if (comparator.compare(x, (E)c) <= 0) |
626 |
> |
break; |
627 |
> |
queue[k] = c; |
628 |
> |
k = child; |
629 |
|
} |
630 |
+ |
queue[k] = x; |
631 |
|
} |
632 |
|
|
633 |
|
/** |
635 |
|
* assuming nothing about the order of the elements prior to the call. |
636 |
|
*/ |
637 |
|
private void heapify() { |
638 |
< |
for (int i = size/2; i >= 1; i--) |
639 |
< |
fixDown(i); |
638 |
> |
for (int i = (size >>> 1) - 1; i >= 0; i--) |
639 |
> |
siftDown(i, (E)queue[i]); |
640 |
|
} |
641 |
|
|
642 |
|
/** |
667 |
|
s.defaultWriteObject(); |
668 |
|
|
669 |
|
// Write out array length |
670 |
< |
s.writeInt(queue.length); |
670 |
> |
// For compatibility with 1.5 version, must be at least 2. |
671 |
> |
s.writeInt(Math.max(2, queue.length)); |
672 |
|
|
673 |
|
// Write out all elements in the proper order. |
674 |
< |
for (int i=1; i<=size; i++) |
674 |
> |
for (int i=0; i<size; i++) |
675 |
|
s.writeObject(queue[i]); |
676 |
|
} |
677 |
|
|
690 |
|
queue = new Object[arrayLength]; |
691 |
|
|
692 |
|
// Read in all elements in the proper order. |
693 |
< |
for (int i=1; i<=size; i++) |
693 |
> |
for (int i=0; i<size; i++) |
694 |
|
queue[i] = (E) s.readObject(); |
695 |
|
} |
696 |
|
|