本文共 784 字，大约阅读时间需要 2 分钟。

顺序查找

//n 数组长度,key 查找关键字,a为数组int Sequential_Search(int key,int n,int *a){	int i;	for(i = 1;i<=n;i++)	{		if(a[i] == key)			return i;	}	return 0;}

改进的算法，设置哨兵，效率比第一个高

int Seqential_Search_new(int key,int n,int *a) {		int i;	a[0] = key;/*设置哨兵,避免每次比较后都要判断查找位置是否越界*/	i = n;/*循环从尾部开始*/	while(a[i] != key)	{		i--;	}	return i;/*返回0 则查找失败*/}

折半查找，又称二分查找

int Binary_Search(int *a,int n,int key){	int low,high,mid;	low = 1;	high = n;	while(low <= high)	{		mid = (low + high)/2;				if(key < a[mid])			high = mid - 1;		else if(key > a[mid])			low = mid + 1;		else 			return mid;	}	return 0;}