Package net.cscott.jutil

Class BinaryHeap<K,V>

java.lang.Object
net.cscott.jutil.AbstractHeap<K,V>
net.cscott.jutil.BinaryHeap<K,V>
All Implemented Interfaces:
Iterable<Map.Entry<K,V>>, Heap<K,V>
public final class BinaryHeap<K,V> extends AbstractHeap<K,V>
BinaryHeap is an implementation of a binary heap. The implementation in CLR is followed, except the comparisons are reversed to keep the minimum element on the top of the heap. In addition, the function names downheap(int) (for what CLR calls 'heapify') and upheap(int) (which is part of the INSERT operation) have been adopted from Sedgewick's book.
Author:
C. Scott Ananian <cananian@alumni.princeton.edu>
See Also:

  • Constructor Details

    • BinaryHeap

      public BinaryHeap()
      Creates a new, empty BinaryHeap, which will use the keys' natural order.

    • BinaryHeap

      public BinaryHeap(Comparator<? super K> c)
      Creates a new, empty BinaryHeap with the specified comparator.

    • BinaryHeap

      public BinaryHeap(Heap<K,? extends V> h)
      Builds a binary heap from the given heap, using the same key comparator as the given heap. O(n) time.

    • BinaryHeap

      public BinaryHeap(Collection<? extends Map.Entry<? extends K,? extends V>> collection, Comparator<? super K> comparator)
      Builds a binary heap from a collection of Map.Entrys and a key comparator. O(n) time.

  • Method Details

    • insert

      public Map.Entry<K,V> insert(K key, V value)
      Description copied from interface: Heap
      Inserts a node with the specified key and value into the Heap. Returns the generated Map.Entry which may be stored and eventually passed back to decreaseKey() or delete to remove this node.
      Specified by:
      insert in interface Heap<K,V>
      Specified by:
      insert in class AbstractHeap<K,V>

    • minimum

      public Map.Entry<K,V> minimum()
      Description copied from interface: Heap
      Returns a mapping entry with minimal key.
      Specified by:
      minimum in interface Heap<K,V>
      Specified by:
      minimum in class AbstractHeap<K,V>

    • extractMinimum

      public Map.Entry<K,V> extractMinimum()
      Description copied from interface: Heap
      Remove and return a map entry with minimal key.
      Specified by:
      extractMinimum in interface Heap<K,V>
      Overrides:
      extractMinimum in class AbstractHeap<K,V>

    • union

      public void union(Heap<? extends K,? extends V> h)
      Description copied from interface: Heap
      Merges all of the mappings from the specified Heap into this Heap. Note that duplicates are permitted. After calling union(), the Heap passed in as an argument will be empty.

      Note that usually efficient implementations of this method require that the Heap argument be from the same implementation as this. (That is, they must both be binomial heaps, or both fibonacci heaps, etc.)

      Specified by:
      union in interface Heap<K,V>
      Overrides:
      union in class AbstractHeap<K,V>

    • decreaseKey

      public void decreaseKey(Map.Entry<K,V> me, K newkey)
      Description copied from interface: Heap
      Replace the key in the specified map entry with the specified smaller key.
      Specified by:
      decreaseKey in interface Heap<K,V>
      Specified by:
      decreaseKey in class AbstractHeap<K,V>

    • updateKey

      public void updateKey(Map.Entry<K,V> me, K newkey)
      Description copied from interface: Heap
      Replace the key in the specified map entry with the specified key, which may be either larger or smaller than its current key.
      Specified by:
      updateKey in interface Heap<K,V>
      Overrides:
      updateKey in class AbstractHeap<K,V>

    • delete

      public void delete(Map.Entry<K,V> me)
      Description copied from interface: Heap
      Remove the specified map entry from the mapping.
      Specified by:
      delete in interface Heap<K,V>
      Specified by:
      delete in class AbstractHeap<K,V>

    • clear

      public void clear()
      Description copied from interface: Heap
      Removes all entries from this Heap.
      Specified by:
      clear in interface Heap<K,V>
      Specified by:
      clear in class AbstractHeap<K,V>

    • size

      public int size()
      Description copied from interface: Heap
      Returns the number of entries in this Heap.
      Specified by:
      size in interface Heap<K,V>
      Specified by:
      size in class AbstractHeap<K,V>

    • entries

      public Collection<Map.Entry<K,V>> entries()
      Description copied from interface: Heap
      Returns a collection view of all the Map.Entrys in this Heap.
      Specified by:
      entries in interface Heap<K,V>
      Specified by:
      entries in class AbstractHeap<K,V>

    • setKey

      protected final K setKey(Map.Entry<K,V> me, K newkey)
      Description copied from class: AbstractHeap
      This method should set the key for the specified Map.Entry to the given newkey. Implementation is optional, but it is required if you use the default implementation of updateKey().
      Overrides:
      setKey in class AbstractHeap<K,V>