代码

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

评测结果