package sortingAlgorithms;

// Problem Title => Implement She'll Sort

/*

* ShellSort is mainly a variation of Insertion Sort.

* In insertion sort, we move elements only one position ahead.

* When an element has to be moved far ahead, many movements are involved.

* The idea of shellSort is to allow exchange of far items.

* In shellSort, we make the arrays.array h-sorted for a large value of h.

* We keep reducing the value of h until it becomes

* 1. An arrays.array is said to be h-sorted if all sub-linkedList.list's of every h’th element is sorted.

*

* */

public class Shell_Sort {

/* A utility function to print arrays.array of size n*/

static void printArray(int[] arr) {

// int n = arr.length;

for (int j : arr) System.out.print(j + " ");

System.out.println();

}

/* function to sort arr using shellSort */

int sort(int[] arr) {

int n = arr.length;

// Start with a big gap, then reduce the gap

for (int gap = n/2; gap > 0; gap /= 2) {

// Do a gaped insertion sort for this gap size.

// The first gap elements a[0..gap-1] are already in gaped order keep adding one more element until the entire arrays.array is gap sorted

for (int i = gap; i < n; i += 1) {

// add a[i] to the elements that have been gap sorted save a[i] in temp and make a hole at position i

int temp = arr[i];

// shift earlier gap-sorted elements up until the correct location for a[i] is found

int j;

for (j = i; j >= gap && arr[j - gap] > temp; j -= gap)

arr[j] = arr[j - gap];

// put temp (the original a[i]) in its correct location

arr[j] = temp;

}

}

return 0;

}

// Driver method

public static void main(String[] args) {

int[] arr = {12, 34, 54, 2, 3};

System.out.println("Array before sorting");

printArray(arr);

Shell_Sort ob = new Shell_Sort();

ob.sort(arr);

System.out.println("Array after sorting");

printArray(arr);

}

}