查找第n小元素
#include <stdio.h> #include <stdlib.h> #include <malloc.h> #include <time.h> 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[nKey]); return i+1; } int RandomPartiton(int *pnArr, int nLeft, int nRight) { srand(time(NULL)); int i = rand()%(nRight - nLeft + 1) + nLeft; Swap(&pnArr[i], &pnArr[nRight]); return Partition(pnArr, nLeft, nRight); } //i 第i小元素 int RandomSelect(int *pnArr, int nLeft, int nRight, int i) { if (nLeft == nRight) { return pnArr[nLeft]; } //寻找一个nTmpPos下标,nTmpPos左边的值都小于它,右边的值都大于它 int nTmpPos = RandomPartiton(pnArr, nLeft, nRight); int nLCount = nTmpPos - nLeft + 1; if (nLCount == i) { return pnArr[nTmpPos]; } else if (i < nLCount) { return RandomSelect(pnArr, nLeft, nTmpPos - 1, i); } else { return RandomSelect(pnArr, nTmpPos + 1, nRight, i - nLCount); } } int main() { int nArr[10] = {0,2,1,3,5,6,9,7,4,12}; PrintArr(nArr, 10); printf("第5最小元素的值为%d\n", RandomSelect(nArr, 0, 9, 5)); system("pause"); return 0; }
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