I am a fresh software engineering graduate and I am looking for something to improve my problem solving skills, while I did learn about basic algorithms and data structures, I feel like I could learn further more, I know about big O, fast sorting algorithms, dynamic programming, backtracking, binary trees (Although I do not think I know everything about them), I also know about low level memory concepts.
I am sure I forgot to mention some of the stuff I also know about, but I hope the ones I mentioned give a good insights on where I should move onto next.
There are plenty of good resources online. Here are some topics you probably wouldn’t see in an intro algos course (which I’ve actually used in my career). And I highly recommend finding the motivation for each of these in application rather than just learning them abstractly.