I cannot stress enough how important mathematical foundations is. It'll make everything else much easier to learn. I haven't read the book but heard good things about: https://www.amazon.com/Discrete-Mathematics-Applications-Sus... as a beginner text.
Coursera has multiple offerings on Data Structures / Algorithms -- find one that works best for you.
By doing all of those you'll get a good introductory exposure to the topics.
You should also look at a rigorous course offering of Algorithms. MIT has a few online to view.
Some readings for a beginner are:
https://www.amazon.com/Introduction-Algorithms-3rd-MIT-Press... (not beginner level but classic)
After all of this you should be fine with diving into interview books. You'll want to whiteboard solutions and be able to do all the difficult problems. Look into sites like leetcode, glassdoor and be able to do the difficult problems posted there.