Learning an algorithm and data structure for a month and forgetting about it after exploring a new language be like🤦

seems you gotta revisit all that stuff. my recommendation: do your exercises on paper. it helps build a better understanding than implementing stuff in a programming language.

I always strive to build a repository of knowledge. I can always google how exactly an R-tree, quicksort, swiss table or any other known device works, or even their time complexity. What I need to know is their use cases and most important properties, so that I know when to google which name.

Although quicksort is fairly basic, it should be routine for people whose main responsibility is programming and they aren't doing it as an extension of another field of expertise.

Also swiss tables are brilliant and everyone should know them. They're better than basic hashmaps in pretty much every scenario and they demonstrate a lot of fundamental optimization techniques.