希爾排序

#include<iostream>
using namespace std;

void ShellInsert(int *a, int length, int n) 
{
	int i, j;
	for (i = n + 1; i <= length; i++)
	{
		if (a[i] < a[i - n])
		{
			a[0] = a[i];  //備份a[i]
			for (j = i - n; j>0 && a[0] < a[j]; j -= n)
			{
				a[j + n] = a[j];
			}
			a[j + n] = a[0];
		}

	}
}
void ShellSort(int *a, int length, int n)//n爲增量
{
	int i;
	for (i = n; i > 0; i--)
		ShellInsert(a, length, i);
}
int main()
{
	int a[] = { 0, 23, 14, 56, 18, 2, 6, 34, 12 };
	int length = sizeof(a) / sizeof(a[0]) - 1;
	ShellSort(a, length, 3);
	for (int i = 1; i <= length; i++)
	{
		printf("%d ", a[i]);
	}
	return 0;
}