Shell Sort Algorithm example in Java Programming

Shell Sort Algorithm

Shell Sort Algorithm example in Java programming :

public class ShellSort {

  private long[] data;
  private int len;

  public ShellSort(int max) {

    data = new long[max];
    len = 0;

  }

  public void insert(long value) {

    data[len] = value;
    len++;

  }

  public void display() {

    for (int j = 0; j < len; j++) {

      System.out.print(data[j] + " ");

    }

    System.out.println("");
  }

  public void shellSort() {

    int inner, outer;
    long temp;
    // find initial value of h

    int h = 1;

    while (h <= len / 3) {

      h = h * 3 + 1; // (1, 4, 13, 40, 121, ...)
    }

    while (h > 0) // decreasing h, until h=1
    {
      // h-sort the file
      for (outer = h; outer < len; outer++) {

        temp = data[outer];
        inner = outer;

        // one subpass (eg 0, 4, 8)
        while (inner > h - 1 && data[inner - h] >= temp) {

          data[inner] = data[inner - h];
          inner -= h;

        }

        data[inner] = temp;
      }

      h = (h - 1) / 3; // decrease h
    }
  }

  public static void main(String[] args) {

    int maxSize = 10;
    ShellSort arr = new ShellSort(maxSize);

    for (int j = 0; j < maxSize; j++) {

      long n = (int) (java.lang.Math.random() * 99);
      arr.insert(n);

    }

    System.out.print("Unsorted List:\n");
    arr.display();

    arr.shellSort();

    System.out.print("-------------------------\n");
    System.out.print("Sorted List:\n");
    arr.display();
  }
}

OUTPUT

Unsorted List:
22 7 29 28 4 75 32 83 2 59 
-------------------------
Sorted List:
2 4 7 22 28 29 32 59 75 83