After completing the time analysis for an algorithm I have been working on, I need some help to write its time complexity properly, let me describe how it works...
The algorithm has two inputs $x$ and $y$.
When $x < 15$, steps to solve are $2^y$, so I know this is $O(2^y)$.
However when $ x >= 15$, the steps to solve begin ramping down (from the $2^y$) at a rate of $-1\%$ as $x$ increases, up to $x < 50$ (don't know how to express this part)
And then, when $x>=50$ it flats out, and keep the same cost, that is $O(2^y*35\%)$, and doesn't matter what is the value of $x$ (as long as it is greater than $50$)
How to write a time complexity that has 3 delimited phases depending on the inputs?