快速排序C++实现

    //快速排序  
    #include<iostream>  
    #include<functional>  
    #include<Windows.h>  
      
    using namespace std;  
      
    void qksort(int* arr,int cnt)  
    {  
        function<int(int*,int,int)> getPivot = [&](int* arr,int left,int right)->int  
        {  
            int mid = (left + right) / 2;  
            if (arr[left] > arr[mid])  
                swap(arr[left],arr[mid]);     
            if (arr[left] > arr[right])  
                swap(arr[left],arr[right]);  
            if (arr[mid] > arr[right])  
                swap(arr[mid],arr[right]);  
            swap(arr[mid],arr[right - 1]);  
            return arr[right - 1];  
        };  
      
        function<void(int*,int)> insertSort = [&](int* arr,int begin,int end)  
        {  
            int i = 0,j = 0;  
            for (i = begin + 1; i <= end; i++)  
            {  
                int tmp = arr[i];  
                for (j = i; j > begin && arr[j - 1] > tmp; j--)  
                    arr[j] = arr[j - 1];  
                arr[j] = tmp;  
            }  
        };  
      
        function<void(int*,int)> qk = [&](int* arr,int right)  
        {  
            if (left + 9 <= right)    //当数组元素大于等于10个的时候，我们用快速排序  
            {  
                int pivot = getPivot(arr,left,right);  
                int i = left;  
                int j = right - 1;  
                while (1)  
                {  
                    while (arr[++i] < pivot){}  
                    while (arr[--j] > pivot){}  
                    if (i < j)  
                        swap(arr[i],arr[j]);  
                    else  
                        break;  
                }  
                swap(arr[i],arr[right - 1]);  
                qk(arr,i - 1);  
                qk(arr,i + 1,right);  
            }  
            else                //当数组元素小于10个的时候我们用插入排序  
                insertSort(arr,right);  
        };  
      
        qk(arr,cnt - 1);  
    };  
      
    int main()  
    {  
        int arr[1000];  
        int tmp = -1;  
      
        for (int i = 0; i < 500; i++)  
        {  
            if (i % 2)  
                arr[i] = i*tmp;  
            else  
                arr[i] = i;  
        }  
        for (int i = 500; i < 1000; i++)  
        {  
            if (i % 2)  
                arr[i] = i*tmp;  
            else  
                arr[i] = i;  
        }  
      
        //我们可以对上面进行全不快排还是部分快排部分插入排序进行时间上的测试，理论上我们元素个数界限是10个，取十个在有些时候不一定是最佳的，但是可以避免一些有害的特殊情形  
        {  
            LARGE_INTEGER  large_interger;  
            double dff;  
            __int64  c1,c2;  
            QueryPerformanceFrequency(&large_interger);  
            dff = large_interger.QuadPart;  
            QueryPerformanceCounter(&large_interger);  
            c1 = large_interger.QuadPart;  
      
            qksort(arr,1000);  
      
            QueryPerformanceCounter(&large_interger);  
            c2 = large_interger.QuadPart;  
            printf("计时%lf毫秒n",(c2 - c1) * 1000 / dff);  
        }  
      
        for (auto i : arr)  
            cout << i << endl;  
      
        cin.get();  
        return 0;  
    }