折半查找

#include "stdafx.h"#include<iostream>#include <time.h>using namespace std;#pragma warning(disable:4996)void HalfSearch(int num[], int left, int right, int nData){int Mid = (right + left) / 2;if (left == right){return;}if (num[Mid] == nData){printf("%d\n", Mid);return;}if (num[Mid] >= nData){HalfSearch(num, left, Mid, nData);}else{HalfSearch(num, Mid, right, nData);}}int _tmain(int argc, _TCHAR* argv[]){int num[9] = {1, 6, 9 , 12, 18, 20, 40, 55, 61};HalfSearch(num, 0, 9, 12);return 0;}

二分查找又称折半查找，优点是比较次数少，查找速度快，平均性能好；其缺点是要求待查表为有序表，且插入删除困难。因此，折半查找方法适用于不经常变动而查找频繁的有序列表