#include <iostream>

using namespace std;

int shellSort(int arr[], int n)

{

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

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

{

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

// The first gap elements a[0..gap-1] are already in gapped order

// keep adding one more element until the entire 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;

}

void printArray(int arr[], int n)

{

for (int i=0; i<n; i++)

cout << arr[i] << " ";

}

int main()

{

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

int n = sizeof(arr)/sizeof(arr[0]);

cout << "Array before sorting: \n";

printArray(arr, n);

shellSort(arr, n);

cout << "\nArray after sorting: \n";

printArray(arr, n);

return 0;

}