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：