What is the complexity of the proposed solution with character removal and reversal? Can the algorithm be improved?

If the solution involves removing characters from a string and then reversing it, the complexity usually depends on the length of the string n. Removing characters can be implemented in a single pass — O(n), reversing the string also O(n), so the total time complexity is — O(n).

Can it be improved? If the problem allows, you can combine the removal and reversal operations into one pass, for example, by iterating over the string from the end, simultaneously filtering characters, which will allow doing everything in one pass — still O(n), but with a smaller constant factor and less memory usage.

Example in Python:

s = "example"
# Remove characters 'a' and 'e', then reverse
result = ''.join(c for c in reversed(s) if c not in {'a', 'e'})
print(result)  # Output: lpmx

Thus, the algorithm is optimized by combining operations, but the asymptotic complexity remains linear.