You never know if you are free to use the solution you have come up with yourself. This is discouraging and can be extremely frustrating. But this is what patents can do. I remembered John Carmack’s quote:
The idea that I can be presented with a problem, set out to logically solve it with the tools at hand, and wind up with a program that could not be legally used because someone else followed the same logical steps some years ago and filed for a patent on it is horrifying.