希尔排序

//*****************************希尔排序****************************

//思路：把数据分为几组，每组有gap个数据，gap可以是固定的，也可根据

//      数组的大小来变动，做法和插入排序一样，只是每次数据后移时要后移

//      gap个位置，end--的时候也要移动gap个位置

//NOTE：end+gap不能超过数组的最大下标，否则会取到随机数

//      while (end >= 0 && a[end]>tmp && end + gap < size)

//      或者在for循环里面控制for (int index = 0; index < size - gap; ++index)

void ShellSort( int * a , size_t size )

{

                 assert ( a );

                 int gap = size ;

                 while (gap > 1)

                {

                                gap = gap / 3 + 1;

                                 for ( int index = 0; index < size ; index++)

                                {

                                                 int end = index;

                                                 int tmp = a [end + gap];

                                                 while (end >= 0 && a [end]>tmp /* && end + gap < size*/ )

                                                {

                                                                 a [end + gap] = a [end];

                                                                end -= gap;;

                                                }

                                                 a [end + gap] = tmp;

                                }

                }

}

void ShellSortTest()

{

                 //int arr[] = { 9, 5, 4, 2, 3, 6, 8, 0, 1, 7 };

                 int arr[] = { 9, 5, 4, 2, 5, 6, 8, 5, 1, 7 };

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

                ShellSort(arr, _size);

                Print(arr, _size);

}