Merge sort : Sort Search « Collections Data Structure « Java

Merge sort

Merge sort
public class MergeSortArray {
  private long[] theArray; 

  private int nElems; 

  public MergeSortArray(int max) {
    theArray = new long[max];
    nElems = 0;

  public void insert(long value) {
    theArray[nElems] = value; // insert it
    nElems++; // increment size

  public void display() {
    for (int j = 0; j < nElems; j++)
      System.out.print(theArray[j] + " ");

  public void mergeSort() {
    long[] workSpace = new long[nElems];
    recMergeSort(workSpace, 0, nElems - 1);

  private void recMergeSort(long[] workSpace, int lowerBound, int upperBound) {
    if (lowerBound == upperBound) // if range is 1,
      return; // no use sorting
    else { // find midpoint
      int mid = (lowerBound + upperBound) / 2;
      // sort low half
      recMergeSort(workSpace, lowerBound, mid);
      // sort high half
      recMergeSort(workSpace, mid + 1, upperBound);
      // merge them
      merge(workSpace, lowerBound, mid + 1, upperBound);

  private void merge(long[] workSpace, int lowPtr, int highPtr, int upperBound) {
    int j = 0; // workspace index
    int lowerBound = lowPtr;
    int mid = highPtr - 1;
    int n = upperBound - lowerBound + 1; // # of items

    while (lowPtr <= mid && highPtr <= upperBound)
      if (theArray[lowPtr] < theArray[highPtr])
        workSpace[j++] = theArray[lowPtr++];
        workSpace[j++] = theArray[highPtr++];

    while (lowPtr <= mid)
      workSpace[j++] = theArray[lowPtr++];

    while (highPtr <= upperBound)
      workSpace[j++] = theArray[highPtr++];

    for (j = 0; j < n; j++)
      theArray[lowerBound + j] = workSpace[j];

  public static void main(String[] args) {
    int maxSize = 100; // array size
    MergeSortArray arr = new MergeSortArray(maxSize); // create the array






Related examples in the same category

1.Linear search
2.Animation for quick sort
3.Quick Sort Implementation with median-of-three partitioning and cutoff for small arrays
4.Simple Sort DemoSimple Sort Demo
5.A simple applet class to demonstrate a sort algorithm
6.Sorting an array of StringsSorting an array of Strings
7.Simple version of quick sortSimple version of quick sort
8.Combine Quick Sort Insertion SortCombine Quick Sort Insertion Sort
9.Quick sort with median-of-three partitioningQuick sort with median-of-three partitioning
10.Fast Quick Sort
11.Selection sortSelection sort
12.Insert Sort for objectsInsert Sort for objects
13.Insert sortInsert sort
14.Bubble sortBubble 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.