题目

快排改良

解决代码及点评

#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#include <time.h>#define K 3
void PrintArr(int *pnArr, int nLen)
{for (int i = 0; i < nLen; i++){printf("%d ", pnArr[i]);}printf("\n");
}void Swap(int *p1, int *p2)
{int nTmp = *p1;*p1 = *p2;*p2 = nTmp;
}int Partition(int *pnArr, int nLeft, int nRight)
{int nKey = nRight;int i = nLeft - 1;for (int j = nLeft; j < nRight; j++){if (pnArr[j] < pnArr[nKey]){i++;Swap(&pnArr[i], &pnArr[j]);}}Swap(&pnArr[i+1], &pnArr[nRight]);return i + 1;
}
int RandomPartition(int *pnArr, int nLeft, int nRight)
{srand(time(NULL));int n1 = rand()%(nRight - nLeft + 1) + nLeft;int n2 = rand()%(nRight - nLeft + 1) + nLeft;int n3 = rand()%(nRight - nLeft + 1) + nLeft;int nKey = (n1+n2+n3) / 3;Swap(&pnArr[nKey], &pnArr[nRight]);return Partition(pnArr, nLeft, nRight);
}void InsertSort(int *pnArr, int nLeft, int nRight)
{for (int i = nLeft + 1; i <= nRight; i++){int nTmp = pnArr[i];int j;for (j = i; j > nLeft && nTmp <pnArr[j-1]; j--){pnArr[j] = pnArr[j-1];}pnArr[j] = nTmp;}
}
void QuickSort(int *pnArr, int nLeft, int nRight)
{if (nLeft < nRight){if (nRight - nLeft > K){int nTmpPos = RandomPartition(pnArr, nLeft, nRight);QuickSort(pnArr, nLeft, nTmpPos - 1);QuickSort(pnArr, nTmpPos + 1, nRight);}else{InsertSort(pnArr, nLeft, nRight);}}
}
int main()
{int nArr[10] = {42,1,3,2,16,9,10,14,8,17}; PrintArr(nArr, 10);QuickSort(nArr, 0,9);PrintArr(nArr, 10);system("pause");return 0;
}

代码下载及其运行

代码下载地址：http://download.csdn.net/detail/yincheng01/6858815

解压密码：c.itcast.cn

下载代码并解压后，用VC2013打开interview.sln，并设置对应的启动项目后，点击运行即可，具体步骤如下：

1）设置启动项目：右键点击解决方案，在弹出菜单中选择“设置启动项目”

2）在下拉框中选择相应项目，项目名和博客编号一致

3）点击“本地Windows调试器”运行

程序运行结果