希爾排序

使用希爾增量時排序的最壞爲：O(n^2);

代碼以下：

 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 }

運行結果爲：