The algorithm design manual by skienna is a popular choice. The first half is more instructional regarding different classes of algorithms and datastructures and how they should be used while the second half is like an encyclopedia of descriptions of various algorithms. It's a very approachable read and I've found it to be a great book, all around.

A lot of people recommend the super heavy tome textbooks, which could be useful, but I feel like from your description you'd be better off with this

"CS skills" is broad, and mostly irrelevant for a DevOps role.

Computer Science can be quite fascinating and can involve considering fancy data structures/algorithms, applications of linear algebra in terms of computer graphics / computer visions, machine learning or AI.. or stuff like how a compiler or a search engine works.

But I'd say moving from System Administration to DevOps, it's more important to know software development skills (like using version control software, or how to achieve the things you'd do as a sysadmin using a programming languague) than it is to know about algorithms for balancing a binary search tree, or to crank out leetcode problems.

For a very basic intro, "A common sense guide to data structures and algorithms" and "Grokking algorithms" are a couple of good books.

I've had good success with some Finnish MOOC on java when I had a teacher who didn't even know what RAM was. I had to learn quick unfortunately cause she just graded if it was right to wrong. But even with probably writing over a couple thousand lines it code, I don't think I became comfortable with OOP until like 6 months in. Personally, I think C# and Java are the easiest to learn and I don't care what anybody says. C/C++ gets hardcore fast and makes things frustrating. Web Dev gets boring because you mess with html tags and css more than you do javascript.

1. Trial by fire; learning on the job

2. CS stuff is widely available for self-study if you've got good discipline. "The Algorithm Design Manual" by Skiena is my favorite textbook on algorithm fundamentals. CLRS is a bigger book with more mathy crunch, if you're into that.

There's a lot more to computer science and software engineering than just algorithms, but it's what you'll get grilled on the most in junior level interviews. By the same token, the skills you need as you get more senior in this industry aren't really taught in school.

> need to learn this stuff.

If you are a traditional sysadmin with limited programming experience, then you have a very tough road ahead of you in 2021 - getting up to speed now is not picking up "stuff", think of it as a new career.

You should stay at your current job and work on devops projects to learn the devops tools and skills and get proficient at basic programming first.

After that, start on more advanced programming.

If that doesn't get you through interviews, then LeetCode. I put this last because even with a fair amount of practise, most people can't finish a difficult problem in 30 or 60 minutes and pass the test suite.

I don't get why interviewers sometimes start with, "Sorry, this is the problem, but nobody ever finishes it." (One was write a hash library with tests in 30 minutes, for a devops role.) You just have to move on to the next company.