代码

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

评测结果