改进版本的快速排序

#include<iostream>#include<fstream>#include<ctime>using namespace std;inline void Swap(int& a,int& b){int t=a;a=b;b=t;}inline int findPivot(int* array,int l,int r){//r-l>=offset (10)int center=l+(r-l)/2;if(array[l]>array[center]) Swap(array[l],array[center]);if(array[l]>array[r]) Swap(array[l],array[r]);if(array[center]>array[r]) Swap(array[center],array[r]);Swap(array[center],array[r-1]);return array[r-1];}inline void insertionSort(int* array,int l){for(int i=1;i<l;++i){int t=array[i];int j;for(j=i-1;j>=0;--j)if(array[j]>t)array[j+1]=array[j];else break;array[j+1]=t;}}void Qsort(int* array,int l,int r){static int offset=10;if(l+offset<=r){int t=findPivot(array,l,r);int i=l,j=r-1;while(1){while(array[++i]<t);while(array[--j]>t);if(i>=j)break;Swap(array[i],array[j]);}Swap(array[i],array[r-1]);Qsort(array,l,i-1);Qsort(array,i+1,r);}else insertionSort(array+l,r-l+1);}void QSort(int* array,int l){Qsort(array,0,l-1);}int main(){const int MAX=1000000;int *array=new int[MAX];ifstream in("millionNumbers.txt");clock_t b,e;b=clock();{int t;for(int i=0;i<MAX;++i){in>>t;array[i]=t;}}e=clock();cout<<"time of reading file is: "<<(e-b)<<" ms"<<endl;b=clock();QSort(array,MAX);e=clock();cout<<"time of qsort is: "<<(e-b)<<" ms"<<endl;ofstream out("QSort.txt");for(int i=0;i<MAX;++i)out<<array[i]<<"/t";delete[] array;return 0;}