希尔排序

使用希尔增量时排序的最坏为：O(n^2);

代码如下：

 1 #include <iostream>

 2 #include <vector>

 3 using namespace std;

 4 template <typename Comparable>

 5 void shellsort(vector<Comparable> & a)

 6 {

 7     for(int gap = a.size()/2; gap > 0; gap /= 2)

 8         for(int i = gap; i < a.size() ; i++)

 9         {

10             Comparable tmp = a[i];

11             int j = i;

12 

13             for( ; j>=gap && tmp<a[j-gap] ; j -= gap)

14                 a[j] = a[j-gap];

15             a[j]=tmp;

16         }

17 }

18 int main()

19 {

20     vector<int> ivec;

21     ivec.push_back(1);

22     ivec.push_back(9);

23     ivec.push_back(2);

24     ivec.push_back(10);

25     ivec.push_back(3);

26     ivec.push_back(11);

27     ivec.push_back(4);

28     ivec.push_back(12);

29     ivec.push_back(5);

30     ivec.push_back(13);

31     ivec.push_back(6);

32     ivec.push_back(14);

33     ivec.push_back(7);

34     ivec.push_back(15);

35     ivec.push_back(8);

36     ivec.push_back(16);

37     shellsort(ivec);

38     for(int i=0;i<ivec.size();i++)

39         cout<<ivec[i]<<endl;

40     return 0;

41 }

运行结果为：