代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	int l=0,r=n-1;
	while(l<=r)
	{
		int mid=(l+r)>>1;
		if(x==a[mid])
		{
			return mid;
		}
		if(x<a[mid])
		{
			r=mid-1;
		}
		else
		{
			l=mid;
		}
	}
	return -1;
}

评测结果