Terrier IR Platform
2.2.1

## uk.ac.gla.terrier.utility Class HeapSort

```java.lang.Object uk.ac.gla.terrier.utility.HeapSort
```

`public class HeapSortextends java.lang.Object`

An implementation of the heap sort algorithm as described in Cormen et al. Introduction to Algorithms. This class sorts two arrays, with respect to the values of the elements in the first array. There is also an option to sort only N entries with the highest values. In this case, there are two options:

• The top N entries can be sorted in ascending order, so that the N elements with the highest values are placed in the array's last N positions (the highest entry of the arrays will be in array[array.length-1], the second highest in array[array.length-2] and so on.
• The top N entries can be sorted in descending order, so that the N elements with the highest values are placed in the array's first N positions (the highest entry of the array will be in array, the second highest entry will be in array and so on.

Version:
\$Revision: 1.12 \$
Author:
Vassilis Plachouras

Constructor Summary
`HeapSort()`

Method Summary
`static void` ```ascendingHeapSort(double[] A, int[] B, short[] C)```
Sorts the given arrays in ascending order, using heap-sort.
`static void` ```ascendingHeapSort(double[] A, int[] B, short[] C, int topElements)```
Sorts the top topElements of the given array in ascending order, using heap sort.
`static void` ```descendingHeapSort(double[] A, int[] B, short[] C)```
Sorts the given arrays in descending order, using heap-sort.
`static void` ```descendingHeapSort(double[] A, int[] B, short[] C, int topElements)```
Sorts the top topElements of the given array in descending order, using heap sort for sorting the values in ascending order and then reversing the order of a specified number of elements.

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

Constructor Detail

### HeapSort

`public HeapSort()`
Method Detail

### ascendingHeapSort

```public static void ascendingHeapSort(double[] A,
int[] B,
short[] C)```
Sorts the given arrays in ascending order, using heap-sort.

Parameters:
`A` - double[] the first array to be sorted.
`B` - int[] the second array to be sorted, according to the values of the first array.

### descendingHeapSort

```public static void descendingHeapSort(double[] A,
int[] B,
short[] C)```
Sorts the given arrays in descending order, using heap-sort.

Parameters:
`A` - double[] the first array to be sorted.
`B` - int[] the second array to be sorted, according to the values of the first array.

### ascendingHeapSort

```public static void ascendingHeapSort(double[] A,
int[] B,
short[] C,
int topElements)```
Sorts the top topElements of the given array in ascending order, using heap sort.

Parameters:
`A` - double[] the first array to be sorted.
`B` - int[] the second array to be sorted, according to the values of the first array.
`topElements` - int the number of elements to be sorted.

### descendingHeapSort

```public static void descendingHeapSort(double[] A,
int[] B,
short[] C,
int topElements)```
Sorts the top topElements of the given array in descending order, using heap sort for sorting the values in ascending order and then reversing the order of a specified number of elements.

Parameters:
`A` - double[] the first array to be sorted.
`B` - int[] the second array to be sorted, according to the values of the first array.
`topElements` - int the number of elements to be sorted.

Terrier IR Platform
2.2.1

Terrier Information Retrieval Platform 2.2.1. Copyright 2004-2008 University of Glasgow