希尔排序

void shellsort(int *data, size_t size)
{
    for (int gap = size / 2; gap > 0; gap /= 2)
        for (int i = gap; i < size; ++i)
        {
 
             int key = data[i];
             int j = 0;
             for( j = i -gap; j >= 0 && data[j] > key; j -=gap)
             {
                data[j+gap] = data[j];
              }  
             data[j+gap] = key;
         }
}

　　概念很简单，就是先跳着排，然后跳跃排序顺序逐渐变短