折半查找

最新推荐文章于 2025-05-31 16:01:53 发布

原创最新推荐文章于 2025-05-31 16:01:53 发布 · 310 阅读

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//二分法查找
int as_bi_search(int a[],int n,int e)//数组升序排列
{
	int mid;
	int left = 0;
	int right = n - 1;
	while(left < right)
	{
		mid = (left + right) / 2;
		if(e == a[mid])
		{
			return mid ;
		}
		if(e<a[mid])
		{
			left = mid + 1;
			
		}
		if(e>a[mid])
		{
			right = mid - 1;
			
		}
	}

	return mid;
}
int de_bi_search(int a[],int n,int e)//数组降序排列
{
	int mid;
	int left = 0;
	int right = n - 1;
	while(left < right)
	{
		mid = (left + right) / 2;
		if(e == a[mid])
		{
			return mid ;
		}
		if(e>a[mid])
		{
			left = mid + 1;
			
		}
		if(e<a[mid])
		{
			right = mid - 1;
			
		}
	}

	return mid;
}




int main()
{
	int a[] = {11,10,9,8,7,6,5,4,3,2,1};
    int n = sizeof(a)/sizeof(a[0]);//数组长度
	int ret = de_bi_search(a,11,6);
	printf("%d\n",a[ret]);
	printf("%d\n",ret);
	return 0;
}

//折半查找；前题条件必须是有序数组，并且按照一定的顺序排好顺序