it.unimi.dsi.fastutil.ints

Class IntIndirectHeaps

java.lang.Object

it.unimi.dsi.fastutil.ints.IntIndirectHeaps

public class IntIndirectHeaps
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

Methods

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

Methods inherited from class java.lang.Object

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

Method Detail

downHeap

public static int downHeap(int[] refArray,
           int[] heap,
           int[] inv,
           int size,
           int i,
           IntComparator 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 int upHeap(int[] refArray,
         int[] heap,
         int[] inv,
         int size,
         int i,
         IntComparator 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 void makeHeap(int[] refArray,
            int offset,
            int length,
            int[] heap,
            int[] inv,
            IntComparator 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 void makeHeap(int[] refArray,
            int[] heap,
            int[] inv,
            int size,
            IntComparator 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.