代码

int binary_search(const unsigned *a, int n, register unsigned x)
{
	register int l = 0, r = n - 1;
	do
	{
		register int mid = (l + r) / 2;
		a[mid] < x ? (l = mid + 1) : (r = mid);
	}
	while (l != r);
	return l;
}

评测结果