快速排序

  1 #include <iostream>  2 #include <vector>  3 using namespace std;  4 template <typename Comparable>  5 void quicksort( vector<Comparable> & a)  6 {  7     quicksort(a,0,a.size()-1);  8 }  9 template <typename Comparable> 10 const Comparable & median3(vector<Comparable> & a,int left,int right) 11 { 12     int center = (left + right)/2; 13     if(a[center] < a[left]) 14         swap(a[left],a[center]); 15     if(a[right] < a[left]) 16         swap(a[left],a[right]); 17     if(a[right] < a[center]) 18         swap(a[center],a[right]); 19  20     swap(a[center],a[right - 1]); 21     return a[right-1]; 22 } 23 template <typename Comparable> 24 void quicksort( vector<Comparable> & a,int left,int right) 25 { 26     if(left + 10 <= right) 27     { 28         Comparable pivot = median3(a,left,right); 29  30         int i=left,j=right-1; 31         for( ; ; ) 32         { 33             while(a[++i] < pivot){} 34             while(pivot < a[--j]){} 35             if(i<j) 36                 swap(a[i],a[j]); 37             else 38                 break; 39         } 40         swap(a[i],a[right-1]); 41         quicksort(a,left,i-1); 42         quicksort(a,i+1,right); 43     } 44     else 45         insertionSort(a,left,right); 46 } 47 /*template <typename Comparable> 48 void insertionSort(vector<Comparable> & a) 49 { 50     int j; 51     for(int p = 1;p<a.size();p++) 52     { 53         Comparable tmp=a[p]; 54         for(j=p;j>0 && tmp<a[j-1];j--) 55             a[j]=a[j-1]; 56         a[j]=tmp; 57     } 58 } 59 template <typename Iterator,typename Comparator> 60 void insertionSort(const Iterator & begin,const Iterator & end,Comparator lessThan) 61 { 62     if(begin != end) 63         insertionSort(begin,end,lessThan,*begin); 64 } 65 template <typename Iterator,typename Comparator,typename Object> 66 void insertionSort(const Iterator & begin, const Iterator & end , Comparator lessThan,const Object & obj) 67 { 68     Iterator j; 69     for(Iterator p =begin+1;p != end;++p) 70     { 71         Object tmp = *p; 72         for(j=p; j!=begin && lessThan(tmp,*(j-1)); --j) 73             *j = *(j-1); 74         *j = tmp; 75     } 76 }*/ 77 int main() 78 { 79     vector<int> ivec; 80     ivec.push_back(1); 81     ivec.push_back(9); 82     ivec.push_back(2); 83     ivec.push_back(10); 84     ivec.push_back(3); 85     ivec.push_back(11); 86     ivec.push_back(4); 87     ivec.push_back(12); 88     ivec.push_back(5); 89     ivec.push_back(13); 90     ivec.push_back(6); 91     ivec.push_back(14); 92     ivec.push_back(7); 93     ivec.push_back(15); 94     ivec.push_back(8); 95     ivec.push_back(16); 96     quicksort(ivec); 97     for(int j = 0;j<ivec.size();j++) 98         cout<<ivec[j]<<endl; 99     return 0;100 }