Ok, now I assume that time-limit for every kata is 5 secs. You atleast need to provide how many tests are being made. And by "deciding time-complexity", I mean say for instance if a simple O(N^2) solution suffices, why would we want to write a complex O(N) solution? The decision can be made only if you can provide number of tests, time-limit(which I assume is 5secs) and the processor speed on which the code is being executed. To comprehend better, see a problem on spoj.com

Please include the maximum time with in which the program has to execute. This helps us to decide what time-complexity should our code be written.

Its too easy to solve. Not much coding needed. Perhaps, it would have been better, if the sequences vary.