Java: Shell Sort Algorithm

Java Sorting Algorithm: Exercise-16 with Solution

Write a Java program to sort an array of given integers Shell Sort Algorithm.

According to Wikipedia "Shell sort or Shell's method, is an in-place comparison sort. It can be seen as either a generalization of sorting by exchange (bubble sort) or sorting by insertion (insertion sort). The method starts by sorting pairs of elements far apart from each other, then progressively reducing the gap between elements to be compared. Starting with far apart elements can move some out-of-place elements into position faster than a simple nearest neighbor exchange."

Sample Solution:

Java Code:

import java.util.Arrays;
public class ShellSort {   
    public static void shell(int[] a) {
	int increment = a.length / 2;
	while (increment > 0) {
		for (int i = increment; i < a.length; i++) {
			int j = i;
			int temp = a[i];
			while (j >= increment && a[j - increment] > temp) {
				a[j] = a[j - increment];
				j = j - increment;
			}
			a[j] = temp;
		}
		if (increment == 2) {
			increment = 1;
		} else {
			increment *= (5.0 / 11);
		}
	}
    }

	// Method to test above
    public static void main(String args[])
    {
        ShellSort ob = new ShellSort();
        int nums[] = {7, -5, 3, 2, 1, 0, 45};
        System.out.println("Original Array:");
        System.out.println(Arrays.toString(nums));
        ob.shell(nums);
        System.out.println("Sorted Array:");
        System.out.println(Arrays.toString(nums));
        }        
}

Sample Output:

Original Array:
[7, -5, 3, 2, 1, 0, 45]
Sorted Array:
[-5, 0, 1, 2, 3, 7, 45]

Flowchart:

Java Code Editor:

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