希尔排序

使用希尔增量时排序的最坏为：O(n^2);

代码如下：

#include <iostream>
#include <vector>
using namespace std;
template <typename Comparable>
void shellsort(vector<Comparable> & a)
{
    for(int gap = a.size()/2; gap > 0; gap /= 2)
        for(int i = gap; i < a.size() ; i++)
        {
            Comparable tmp = a[i];
            int j = i;

            for( ; j>=gap && tmp<a[j-gap] ; j -= gap)
                a[j] = a[j-gap];
            a[j]=tmp;
        }
}
int main()
{
    vector<int> ivec;
    ivec.push_back(1);
    ivec.push_back(9);
    ivec.push_back(2);
    ivec.push_back(10);
    ivec.push_back(3);
    ivec.push_back(11);
    ivec.push_back(4);
    ivec.push_back(12);
    ivec.push_back(5);
    ivec.push_back(13);
    ivec.push_back(6);
    ivec.push_back(14);
    ivec.push_back(7);
    ivec.push_back(15);
    ivec.push_back(8);
    ivec.push_back(16);
    shellsort(ivec);
    for(int i=0;i<ivec.size();i++)
        cout<<ivec[i]<<endl;
    return 0;
}

运行结果为：