That’s a huge leap from O(n²) to O(n), in this example it would likely good to at least specify that it should be strictly less than best known solution (not sure if there are such cases on leet code, I thought they only restrict you to what is known to be solvable)
Likely they want a lower time complexity.
for example a question can be trivially solved in O(n^2). but there is no know < O(n) solution, so they ask for O(n)
Most of the time O(n^2) is optimized to O(n log n). You’ll get some sort of award if you can figure out a sorting function that runs in O(n).
That’s a huge leap from O(n²) to O(n), in this example it would likely good to at least specify that it should be strictly less than best known solution (not sure if there are such cases on leet code, I thought they only restrict you to what is known to be solvable)