代码

#pragma GCC optimize(3)

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

评测结果