代码

int binary_search(const unsigned *a, int n, unsigned x)
{
	const unsigned *l=a,*r=a+n,*mid;
	while(l+1<r)
	{
		mid=l+(r-l)/2;
		if(*mid<=x)	l=mid;
		else	r=mid;
	}
	return l-a;
}

评测结果