For beginners, I've always thought Aho, Hopcroft and Ullman's Data Structures & Algorithms is a bit under-rated [1]. It's short, mathematically inclined and contains very clear Pascal pseudo-code.

[1] https://www.amazon.com/dp/0201000237

Take heart. The interview process is designed to say no. A common anecdote at Google goes like this: "I persuaded the best programmer I know to apply at Google. And we rejected him." These companies say no to all kinds of talented people every day.

Apply again next time you are looking for a job, if Amazon and Google really are the sort of companies you want to work for.

Think back on your interviews and figure out what you did wrong, then study up on that.

And next time, prepare very carefully, with a focus on algorithms and data structures. I would use this book, although it's a bit dated now: https://www.amazon.com/Data-Structures-Algorithms-Alfred-Aho...

This one may also be useful: https://www.amazon.com/Programming-Pearls-2nd-Jon-Bentley/dp...