100-shell_sort.c

#include "sort.h"

void shell_sort(int *array, size_t size);
void swap_shell(int *array, int item1, int item2);

/**
 * shell_sort - sorts an array of integers in ascending
 * order using the Shell sort algorithm, using the Knuth sequence
 * @size: size of the array
 * @array: numbered list
 */

void shell_sort(int *array, size_t size)
{
	size_t gap = 1, i, index = 0;

	if (array == NULL || size < 2)
		return;
	while (gap < size / 3)
		gap = 3 * gap + 1;
	while (gap >= 1)
	{
		for (i = gap; i < size; i++)
			for (index = i; index >= gap &&
					(array[index] < array[index - gap]); index -= gap)
				swap_shell(array, index, index - gap);
		print_array(array, size);
		gap /= 3;
	}
}

/**
 *swap_shell - changes the positions of two elements of an array
 *@array: the array to perform swao
 *@item1: 1st element
 *@item2: 2nd element
 */

void swap_shell(int *array, int item1, int item2)
{

	int tmp;

	tmp = array[item1];
	array[item1] = array[item2];
	array[item2] = tmp;
}