希尔排序（C++模版技术实现）

//
// C++模版技术实现希尔排序.
//

#include <cstdlib>
#include <cstring>
#include <iostream>
#include <stdexcept>

//
// 希尔排序函数模版.
//
template <typename T>
void shellSort(T *array, const size_t first, const size_t last)
{
if (NULL == array || first >= last) {
throw std::invalid_argument("希尔排序参数错误!");
}

const size_t LENGTH = last - first + 1;
size_t gap = LENGTH, i, j;
T temp;

do {
gap = gap / 3 + 1;
//
// 内层循环是直接插入排序，只是各相邻排序元素间隔为 gap.
//
for (i = gap; i < LENGTH; i += gap)
{
temp = array[i];
for (j = i; j >= gap && temp < array[j - gap]; j -= gap)
{
array[j] = array[j - gap];
}
if (j >= 0) {
array[j] = temp;
}
}
} while (gap > 1);
}

//
// 测试.
//
int main(void)
{
char szTest[] = "Shell sort algorithm test case !";
int iarrTest[] = {23, 12, 2, 123, 72, 35, 49, 51, 83, 94, 65};
const size_t INT_ARR_SIZE = sizeof(iarrTest) / sizeof(iarrTest[0]);

shellSort(szTest, 0, strlen(szTest) - 1);
shellSort(iarrTest, 0, INT_ARR_SIZE - 1);

std::cout << szTest << std::endl;

for (size_t i = 0; i < INT_ARR_SIZE; ++i)
{
std::cout << iarrTest[i] << " ";
}
std::cout << std::endl;

return EXIT_SUCCESS;
}