I've seen Leetcode problems that Leetcode classifies as "Hard" where it is actually not at all hard to come up with an algorithm that would solve them in O(n^2) time and/or space, and this would be fast enough in almost all cases, but the problem specification specifically asks for something faster and it is achieving that that makes the problem difficult.

When companies use such a problem do they usually include the time and/or space constraints from Leetcode or are they usually fine with O(n^2)?