BinaryArrayWeakHeap (JHeaps)

java.lang.Object
- org.jheaps.array.BinaryArrayWeakHeap<K>

Type Parameters:

K - the type of keys maintained by this heap

All Implemented Interfaces:

Serializable, Heap<K>

Direct Known Subclasses:

BinaryArrayBulkInsertWeakHeap
```
public class BinaryArrayWeakHeap<K>
extends Object
implements Serializable
```
An array based binary weak heap. The heap is sorted according to the natural ordering of its keys, or by a Comparator provided at heap creation time, depending on which constructor is used.
The implementation uses an array in order to store the elements and automatically maintains the size of the array much like a Vector does, providing amortized O(log(n)) time cost for the insert and deleteMin operations. Operation findMin, is a worst-case O(1) operation. The bounds are worst-case if the user initializes the heap with a capacity larger or equal to the total number of elements that are going to be inserted into the heap.
Constructing such a heap from an array of elements can be performed using the method heapify(Object[]) or heapify(Object[], Comparator) in linear time.
Note that the ordering maintained by a binary heap, like any heap, and whether or not an explicit comparator is provided, must be consistent with equals if this heap is to correctly implement the Heap interface. (See Comparable or Comparator for a precise definition of consistent with equals.) This is so because the Heap interface is defined in terms of the equals operation, but a binary heap performs all key comparisons using its compareTo (or compare) method, so two keys that are deemed equal by this method are, from the standpoint of the binary heap, equal. The behavior of a heap is well-defined even if its ordering is inconsistent with equals; it just fails to obey the general contract of the Heap interface.
Note that this implementation is not synchronized. If multiple threads access a heap concurrently, and at least one of the threads modifies the heap structurally, it must be synchronized externally. (A structural modification is any operation that adds or deletes one or more elements or changing the key of some element.) This is typically accomplished by synchronizing on some object that naturally encapsulates the heap.

Author:

Dimitrios Michail

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type Field and Description

static int DEFAULT_HEAP_CAPACITY
Default initial capacity of the binary heap.

Fields
Modifier and Type	Field and Description
`static int`	`DEFAULT_HEAP_CAPACITY` Default initial capacity of the binary heap.

Constructor Summary

Constructors
Constructor and Description
`BinaryArrayWeakHeap()` Constructs a new, empty heap, using the natural ordering of its keys.
`BinaryArrayWeakHeap(Comparator<? super K> comparator)` Constructs a new, empty heap, ordered according to the given comparator.
`BinaryArrayWeakHeap(Comparator<? super K> comparator, int capacity)` Constructs a new, empty heap, with a provided initial capacity ordered according to the given comparator.
`BinaryArrayWeakHeap(int capacity)` Constructs a new, empty heap, with a provided initial capacity using the natural ordering of its keys.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`clear()` Clear all the elements of this heap.
`Comparator<? super K>`	`comparator()` Returns the comparator used to order the keys in this heap, or `null` if this heap uses the natural ordering of its keys.
`K`	`deleteMin()` Delete and return an element with the minimum key.
`K`	`findMin()` Find an element with the minimum key.
`static <K> BinaryArrayWeakHeap<K>`	`heapify(K[] array)` Create a heap from an array of elements.
`static <K> BinaryArrayWeakHeap<K>`	`heapify(K[] array, Comparator<? super K> comparator)` Create a heap from an array of elements.
`void`	`insert(K key)` Insert a key into the heap.
`boolean`	`isEmpty()` Returns `true` if this heap is empty.
`long`	`size()` Returns the number of elements in this heap.

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - DEFAULT_HEAP_CAPACITY
```
public static final int DEFAULT_HEAP_CAPACITY
```
    Default initial capacity of the binary heap.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - BinaryArrayWeakHeap
```
public BinaryArrayWeakHeap()
```
    Constructs a new, empty heap, using the natural ordering of its keys.
    All keys inserted into the heap must implement the Comparable interface. Furthermore, all such keys must be mutually comparable: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and k2 in the heap. If the user attempts to put a key into the heap that violates this constraint (for example, the user attempts to put a string key into a heap whose keys are integers), the insert(Object key) call will throw a ClassCastException.
    The initial capacity of the heap is DEFAULT_HEAP_CAPACITY and adjusts automatically based on the sequence of insertions and deletions.
  - BinaryArrayWeakHeap
```
public BinaryArrayWeakHeap(int capacity)
```
    Constructs a new, empty heap, with a provided initial capacity using the natural ordering of its keys.
    All keys inserted into the heap must implement the Comparable interface. Furthermore, all such keys must be mutually comparable: k1.compareTo(k2) must not throw a ClassCastException for any keys k1 and k2 in the heap. If the user attempts to put a key into the heap that violates this constraint (for example, the user attempts to put a string key into a heap whose keys are integers), the insert(Object key) call will throw a ClassCastException.
    The initial capacity of the heap is provided by the user and is adjusted automatically based on the sequence of insertions and deletions. The capacity will never become smaller than the initial requested capacity.
    
    Parameters:
    
    capacity - the initial heap capacity
  - BinaryArrayWeakHeap
```
public BinaryArrayWeakHeap(Comparator<? super K> comparator)
```
    Constructs a new, empty heap, ordered according to the given comparator.
    All keys inserted into the heap must be mutually comparable by the given comparator: comparator.compare(k1, k2) must not throw a ClassCastException for any keys k1 and k2 in the heap. If the user attempts to put a key into the heap that violates this constraint, the insert(Object key) call will throw a ClassCastException.
    The initial capacity of the heap is DEFAULT_HEAP_CAPACITY and adjusts automatically based on the sequence of insertions and deletions.
    
    Parameters:
    
    comparator - the comparator that will be used to order this heap. If null, the natural ordering of the keys will be used.
  - BinaryArrayWeakHeap
```
public BinaryArrayWeakHeap(Comparator<? super K> comparator,
                           int capacity)
```
    Constructs a new, empty heap, with a provided initial capacity ordered according to the given comparator.
    All keys inserted into the heap must be mutually comparable by the given comparator: comparator.compare(k1, k2) must not throw a ClassCastException for any keys k1 and k2 in the heap. If the user attempts to put a key into the heap that violates this constraint, the insert(Object key) call will throw a ClassCastException.
    The initial capacity of the heap is provided by the user and is adjusted automatically based on the sequence of insertions and deletions. The capacity will never become smaller than the initial requested capacity.
    
    Parameters:
    
    comparator - the comparator that will be used to order this heap. If null, the natural ordering of the keys will be used.
    
    capacity - the initial heap capacity
- Method Detail
  - heapify
```
public static <K> BinaryArrayWeakHeap<K> heapify(K[] array)
```
    Create a heap from an array of elements. The elements of the array are not destroyed. The method has linear time complexity.
    
    Type Parameters:
    
    K - the type of keys maintained by the heap
    
    Parameters:
    
    array - an array of elements
    
    Returns:
    
    a heap
    
    Throws:
    
    IllegalArgumentException - in case the array is null
  - heapify
```
public static <K> BinaryArrayWeakHeap<K> heapify(K[] array,
                                                 Comparator<? super K> comparator)
```
    Create a heap from an array of elements. The elements of the array are not destroyed. The method has linear time complexity.
    
    Type Parameters:
    
    K - the type of keys maintained by the heap
    
    Parameters:
    
    array - an array of elements
    
    comparator - the comparator to use
    
    Returns:
    
    a heap
    
    Throws:
    
    IllegalArgumentException - in case the array is null
  - findMin
```
public K findMin()
```
    Find an element with the minimum key.
    
    Specified by:
    
    findMin in interface Heap<K>
    
    Returns:
    
    an element with the minimum key
  - insert
```
public void insert(K key)
```
    Insert a key into the heap.
    
    Specified by:
    
    insert in interface Heap<K>
    
    Parameters:
    
    key - the key to insert
  - deleteMin
```
public K deleteMin()
```
    Delete and return an element with the minimum key. If multiple such elements exists, only one of them will be deleted.
    
    Specified by:
    
    deleteMin in interface Heap<K>
    
    Returns:
    
    the deleted element with the minimum key
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if this heap is empty.
    
    Specified by:
    
    isEmpty in interface Heap<K>
    
    Returns:
    
    true if this heap is empty, false otherwise
  - size
```
public long size()
```
    Returns the number of elements in this heap.
    
    Specified by:
    
    size in interface Heap<K>
    
    Returns:
    
    the number of elements in this heap
  - comparator
```
public Comparator<? super K> comparator()
```
    Returns the comparator used to order the keys in this heap, or null if this heap uses the natural ordering of its keys.
    
    Specified by:
    
    comparator in interface Heap<K>
    
    Returns:
    
    the comparator used to order the keys in this heap, or null if this heap uses the natural ordering of its keys
  - clear
```
public void clear()
```
    Clear all the elements of this heap.
    
    Specified by:
    
    clear in interface Heap<K>

Class BinaryArrayWeakHeap<K>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_HEAP_CAPACITY

Constructor Detail

BinaryArrayWeakHeap

BinaryArrayWeakHeap

BinaryArrayWeakHeap

BinaryArrayWeakHeap

Method Detail

heapify

heapify

findMin

insert

deleteMin

isEmpty

size

comparator

clear