Class IntHeapSemiIndirectPriorityQueue
- All Implemented Interfaces:
IndirectPriorityQueue<Integer>
,IntIndirectPriorityQueue
- Direct Known Subclasses:
IntHeapIndirectPriorityQueue
Instances of this class use as reference list a reference array, which must be provided
to each constructor. The priority queue is represented using a heap. The heap is enlarged as
needed, but it is never shrunk. Use the trim()
method to reduce its size, if necessary.
- Implementation Specification:
- This implementation allows one to enqueue several time the same index, but you must be
careful when calling
changed()
.
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Constructor Summary
ConstructorDescriptionIntHeapSemiIndirectPriorityQueue
(int[] refArray) Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int capacity) Creates a new empty queue with given capacity and using the natural order.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int[] a) Wraps a given array in a queue using the natural order.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int[] a, int size) Wraps a given array in a queue using the natural order.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int[] a, int size, IntComparator c) Wraps a given array in a queue using a given comparator.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int[] a, IntComparator c) Wraps a given array in a queue using a given comparator.IntHeapSemiIndirectPriorityQueue
(int[] refArray, int capacity, IntComparator c) Creates a new empty queue without elements with a given capacity and comparator.IntHeapSemiIndirectPriorityQueue
(int[] refArray, IntComparator c) Creates a new empty queue with capacity equal to the length of the reference array and a given comparator. -
Method Summary
Modifier and TypeMethodDescriptionvoid
Rebuilds this heap in a bottom-up fashion (in linear time).void
changed()
Notifies this queue that the first element has changed (optional operation).void
clear()
Removes all elements from this queue.Returns the type-specific comparator associated with this queue.int
dequeue()
Dequeues the first element from this queue.void
enqueue
(int x) Enqueues a new element.int
first()
Returns the first element of this queue.int
front
(int[] a) Writes in the provided array the front of the queue, that is, the set of indices whose elements have the same priority as the top.int
size()
Returns the number of elements in this queue.toString()
void
trim()
Trims the backing array so that it has exactlysize()
elements.
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Constructor Details
-
IntHeapSemiIndirectPriorityQueue
Creates a new empty queue without elements with a given capacity and comparator.- Parameters:
refArray
- the reference array.capacity
- the initial capacity of this queue.c
- the comparator used in this queue, ornull
for the natural order.
-
IntHeapSemiIndirectPriorityQueue
public IntHeapSemiIndirectPriorityQueue(int[] refArray, int capacity) Creates a new empty queue with given capacity and using the natural order.- Parameters:
refArray
- the reference array.capacity
- the initial capacity of this queue.
-
IntHeapSemiIndirectPriorityQueue
Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.- Parameters:
refArray
- the reference array.c
- the comparator used in this queue, ornull
for the natural order.
-
IntHeapSemiIndirectPriorityQueue
public IntHeapSemiIndirectPriorityQueue(int[] refArray) Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.- Parameters:
refArray
- the reference array.
-
IntHeapSemiIndirectPriorityQueue
Wraps a given array in a queue using a given comparator.The queue returned by this method will be backed by the given array. The first
size
element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements ofa
one by one).- Parameters:
refArray
- the reference array.a
- an array of indices intorefArray
.size
- the number of elements to be included in the queue.c
- the comparator used in this queue, ornull
for the natural order.
-
IntHeapSemiIndirectPriorityQueue
Wraps a given array in a queue using a given comparator.The queue returned by this method will be backed by the given array. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of
a
one by one).- Parameters:
refArray
- the reference array.a
- an array of indices intorefArray
.c
- the comparator used in this queue, ornull
for the natural order.
-
IntHeapSemiIndirectPriorityQueue
public IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a, int size) Wraps a given array in a queue using the natural order.The queue returned by this method will be backed by the given array. The first
size
element of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements ofa
one by one).- Parameters:
refArray
- the reference array.a
- an array of indices intorefArray
.size
- the number of elements to be included in the queue.
-
IntHeapSemiIndirectPriorityQueue
public IntHeapSemiIndirectPriorityQueue(int[] refArray, int[] a) Wraps a given array in a queue using the natural order.The queue returned by this method will be backed by the given array. The elements of the array will be rearranged so to form a heap (this is more efficient than enqueing the elements of
a
one by one).- Parameters:
refArray
- the reference array.a
- an array of indices intorefArray
.
-
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Method Details
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enqueue
public void enqueue(int x) Description copied from interface:IndirectPriorityQueue
Enqueues a new element.- Specified by:
enqueue
in interfaceIndirectPriorityQueue<Integer>
- Parameters:
x
- the element to enqueue.
-
dequeue
public int dequeue()Description copied from interface:IndirectPriorityQueue
Dequeues the first element from this queue.- Specified by:
dequeue
in interfaceIndirectPriorityQueue<Integer>
- Returns:
- the dequeued element.
-
first
public int first()Description copied from interface:IndirectPriorityQueue
Returns the first element of this queue.- Specified by:
first
in interfaceIndirectPriorityQueue<Integer>
- Returns:
- the first element.
-
changed
public void changed()Notifies this queue that the first element has changed (optional operation).This default implementation just calls
IndirectPriorityQueue.changed(int)
with argumentIndirectPriorityQueue.first()
.The caller must guarantee that when this method is called the index of the first element appears just once in the queue. Failure to do so will bring the queue in an inconsistent state, and will cause unpredictable behaviour.
- Specified by:
changed
in interfaceIndirectPriorityQueue<Integer>
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allChanged
public void allChanged()Rebuilds this heap in a bottom-up fashion (in linear time).- Specified by:
allChanged
in interfaceIndirectPriorityQueue<Integer>
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size
public int size()Description copied from interface:IndirectPriorityQueue
Returns the number of elements in this queue.- Specified by:
size
in interfaceIndirectPriorityQueue<Integer>
- Returns:
- the number of elements in this queue.
-
clear
public void clear()Description copied from interface:IndirectPriorityQueue
Removes all elements from this queue.- Specified by:
clear
in interfaceIndirectPriorityQueue<Integer>
-
trim
public void trim()Trims the backing array so that it has exactlysize()
elements. -
comparator
Description copied from interface:IntIndirectPriorityQueue
Returns the type-specific comparator associated with this queue.- Specified by:
comparator
in interfaceIndirectPriorityQueue<Integer>
- Specified by:
comparator
in interfaceIntIndirectPriorityQueue
- Returns:
- the comparator associated with this queue.
- See Also:
-
front
public int front(int[] a) Writes in the provided array the front of the queue, that is, the set of indices whose elements have the same priority as the top.- Specified by:
front
in interfaceIndirectPriorityQueue<Integer>
- Parameters:
a
- an array whose initial part will be filled with the frnot (must be sized as least as the heap size).- Returns:
- the number of elements of the front.
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toString
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