Package it.unimi.dsi.fastutil.objects

Class ObjectIndirectHeaps

java.lang.Object
it.unimi.dsi.fastutil.objects.ObjectIndirectHeaps
public final class ObjectIndirectHeaps
extends Object
A class providing static methods and objects that do useful things with indirect heaps.

An indirect heap is an extension of a semi-indirect heap using also an inversion array of the same length as the reference array, satisfying the relation heap[inv[i]]==i when inv[i]>=0, and inv[heap[i]]==i for all elements in the heap.

  • Method Summary

    Modifier and Type Method Description
    static <K> int downHeap​(K[] refArray, int[] heap, int[] inv, int size, int i, Comparator<K> c)
    Moves the given element down into the indirect heap until it reaches the lowest possible position.
    static <K> void makeHeap​(K[] refArray, int[] heap, int[] inv, int size, Comparator<K> c)
    Creates an indirect heap from a given index array.
    static <K> void makeHeap​(K[] refArray, int offset, int length, int[] heap, int[] inv, Comparator<K> c)
    Creates an indirect heap in the given array.
    static <K> int upHeap​(K[] refArray, int[] heap, int[] inv, int size, int i, Comparator<K> c)
    Moves the given element up in the indirect heap until it reaches the highest possible position.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Method Details

    • downHeap

      public static <K> int downHeap​(K[] refArray, int[] heap, int[] inv, int size, int i, Comparator<K> c)
      Moves the given element down into the indirect heap until it reaches the lowest possible position.
      Parameters:
      refArray - the reference array.
      heap - the indirect heap (starting at 0).
      inv - the inversion array.
      size - the number of elements in the heap.
      i - the index in the heap of the element to be moved down.
      c - a type-specific comparator, or null for the natural order.
      Returns:
      the new position in the heap of the element of heap index i.

    • upHeap

      public static <K> int upHeap​(K[] refArray, int[] heap, int[] inv, int size, int i, Comparator<K> c)
      Moves the given element up in the indirect heap until it reaches the highest possible position. Note that in principle after this call the heap property may be violated.
      Parameters:
      refArray - the reference array.
      heap - the indirect heap (starting at 0).
      inv - the inversion array.
      size - the number of elements in the heap.
      i - the index in the heap of the element to be moved up.
      c - a type-specific comparator, or null for the natural order.
      Returns:
      the new position in the heap of the element of heap index i.

    • makeHeap

      public static <K> void makeHeap​(K[] refArray, int offset, int length, int[] heap, int[] inv, Comparator<K> c)
      Creates an indirect heap in the given array.
      Parameters:
      refArray - the reference array.
      offset - the first element of the reference array to be put in the heap.
      length - the number of elements to be put in the heap.
      heap - the array where the heap is to be created.
      inv - the inversion array.
      c - a type-specific comparator, or null for the natural order.

    • makeHeap

      public static <K> void makeHeap​(K[] refArray, int[] heap, int[] inv, int size, Comparator<K> c)
      Creates an indirect heap from a given index array.
      Parameters:
      refArray - the reference array.
      heap - an array containing indices into refArray.
      inv - the inversion array.
      size - the number of elements in the heap.
      c - a type-specific comparator, or null for the natural order.