Quick Sort Implementation with median-of-three partitioning and cutoff for small arrays : Sort Search « Collections Data Structure « Java






Quick Sort Implementation with median-of-three partitioning and cutoff for small arrays

    

public class Main {
  public static void main(String args[]) {
  }

  public static void quicksort(Comparable[] a) {
    quicksort(a, 0, a.length - 1);
  }

  static void quicksort(Comparable[] a, int low, int high) {
    int CUTOFF = 10;
    if (low + CUTOFF > high)
      insertionSort(a, low, high);
    else {
      int middle = (low + high) / 2;
      if (a[middle].compareTo(a[low]) < 0)
        swapReferences(a, low, middle);
      if (a[high].compareTo(a[low]) < 0)
        swapReferences(a, low, high);
      if (a[high].compareTo(a[middle]) < 0)
        swapReferences(a, middle, high);

      swapReferences(a, middle, high - 1);
      Comparable pivot = a[high - 1];

      int i, j;
      for (i = low, j = high - 1;;) {
        while (a[++i].compareTo(pivot) < 0)
          ;
        while (pivot.compareTo(a[--j]) < 0)
          ;
        if (i >= j)
          break;
        swapReferences(a, i, j);
      }
      swapReferences(a, i, high - 1);

      quicksort(a, low, i - 1); 
      quicksort(a, i + 1, high);
    }
  }

  public static final void swapReferences(Object[] a, int index1, int index2) {
    Object tmp = a[index1];
    a[index1] = a[index2];
    a[index2] = tmp;
  }

  private static void insertionSort(Comparable[] a, int low, int high) {
    for (int p = low + 1; p <= high; p++) {
      Comparable tmp = a[p];
      int j;

      for (j = p; j > low && tmp.compareTo(a[j - 1]) < 0; j--)
        a[j] = a[j - 1];
      a[j] = tmp;
    }
  }
}

   
    
    
    
  








Related examples in the same category

1.Linear search
2.Animation for quick sort
3.Simple Sort DemoSimple Sort Demo
4.A simple applet class to demonstrate a sort algorithm
5.Sorting an array of StringsSorting an array of Strings
6.Simple version of quick sortSimple version of quick sort
7.Combine Quick Sort Insertion SortCombine Quick Sort Insertion Sort
8.Quick sort with median-of-three partitioningQuick sort with median-of-three partitioning
9.Fast Quick Sort
10.Selection sortSelection sort
11.Insert Sort for objectsInsert Sort for objects
12.Insert sortInsert sort
13.Bubble sortBubble sort
14.Merge sortMerge sort
15.Fast Merge Sort
16.Binary SearchBinary Search
17.Shell sortShell sort
18.Recursive Binary Search Implementation in Java
19.Topological sortingTopological sorting
20.Heap sortHeap sort
21.Sort NumbersSort Numbers
22.A quick sort demonstration algorithmA quick sort demonstration algorithm
23.Performing Binary Search on Java byte Array Example
24.Performing Binary Search on Java char Array Example
25.Performing Binary Search on Java double Array Example
26.Performing Binary Search on Java float Array Example
27.Performing Binary Search on Java int Array Example
28.Performing Binary Search on Java long Array Example
29.Performing Binary Search on Java short Array
30.Sort items of an array
31.Sort an array of objects
32.Sort a String array
33.Sort string array with Collator
34.Binary search routines
35.FastQ Sorts the [l,r] partition (inclusive) of the specfied array of Rows, using the comparator.FastQ Sorts the [l,r] partition (inclusive) of the specfied array of Rows, using the comparator.
36.A binary search implementation.
37.Handles QuickSort and all of its methods.
38.Implements QuickSort three different ways
39.A quick sort algorithm to sort Vectors or arrays. Provides sort and binary search capabilities.A quick sort algorithm to sort Vectors or arrays. Provides sort and binary search capabilities.
40.Returns an array of indices indicating the order the data should be sorted in.