Class JGraphFibonacciHeap

java.lang.Object
com.jgraph.algebra.JGraphFibonacciHeap
public class JGraphFibonacciHeap extends Object
This class implements a priority queue.

  • Field Details

  • Constructor Details

    • JGraphFibonacciHeap

      public JGraphFibonacciHeap()

  • Method Details

    • getNode

      public JGraphFibonacciHeap.Node getNode(Object element, boolean create)
      Returns the node that represents element.

    • isEmpty

      public boolean isEmpty()

    • decreaseKey

      public void decreaseKey(JGraphFibonacciHeap.Node x, double k)
      Decreases the key value for a heap node, given the new value to take on. The structure of the heap may be changed and will not be consolidated.

      Running time: O(1) amortized

      Parameters:
      x - node to decrease the key of
      k - new key value for node x
      Throws:
      IllegalArgumentException - Thrown if k is larger than x.key value.

    • delete

      public void delete(JGraphFibonacciHeap.Node x)
      Deletes a node from the heap given the reference to the node. The trees in the heap will be consolidated, if necessary. This operation may fail to remove the correct element if there are nodes with key value -Infinity.

      Running time: O(log n) amortized

      Parameters:
      x - node to remove from heap

    • insert

      public void insert(JGraphFibonacciHeap.Node node, double key)
      Inserts a new data element into the heap. No heap consolidation is performed at this time, the new node is simply inserted into the root list of this heap.

      Running time: O(1) actual

      Parameters:
      node - new node to insert into heap
      key - key value associated with data object

    • min

      public JGraphFibonacciHeap.Node min()
      Returns the smallest element in the heap. This smallest element is the one with the minimum key value.

      Running time: O(1) actual

      Returns:
      heap node with the smallest key

    • removeMin

      public JGraphFibonacciHeap.Node removeMin()
      Removes the smallest element from the heap. This will cause the trees in the heap to be consolidated, if necessary. Does not remove the data node so that the current key remains stored.

      Running time: O(log n) amortized

      Returns:
      node with the smallest key

    • size

      public int size()
      Returns the size of the heap which is measured in the number of elements contained in the heap.

      Running time: O(1) actual

      Returns:
      number of elements in the heap

    • union

      public static JGraphFibonacciHeap union(JGraphFibonacciHeap h1, JGraphFibonacciHeap h2)
      Joins two Fibonacci heaps into a new one. No heap consolidation is performed at this time. The two root lists are simply joined together.

      Running time: O(1) actual

      Parameters:
      h1 - first heap
      h2 - second heap
      Returns:
      new heap containing h1 and h2

    • cascadingCut

      protected void cascadingCut(JGraphFibonacciHeap.Node y)
      Performs a cascading cut operation. This cuts y from its parent and then does the same for its parent, and so on up the tree.

      Running time: O(log n); O(1) excluding the recursion

      Parameters:
      y - node to perform cascading cut on

    • consolidate

      protected void consolidate()
      Consolidates the trees in the heap by joining trees of equal degree until there are no more trees of equal degree in the root list.

      Running time: O(log n) amortized

    • cut

      protected void cut(JGraphFibonacciHeap.Node x, JGraphFibonacciHeap.Node y)
      The reverse of the link operation: removes x from the child list of y. This method assumes that min is non-null.

      Running time: O(1)

      Parameters:
      x - child of y to be removed from y's child list
      y - parent of x about to lose a child

    • link

      protected void link(JGraphFibonacciHeap.Node y, JGraphFibonacciHeap.Node x)
      Make node y a child of node x.

      Running time: O(1) actual

      Parameters:
      y - node to become child
      x - node to become parent