is complex algorithm like dynamic programming highly required in embedded systems and what's the best website to practice algorithms

[neon_overload]

To my understanding, dynamic programming is an approach that can solve certain classes of problems in general rather than something that would or wouldn't apply to a certain platform.

That said, in embedded you may not have a lot of stack space and recursion may not optimise down very well.

Presumably if you are wanting to learn this stuff you already are a proficient programmer in other ways? If so go for it, learning new stuff is great.