In my experience, you can't learn that skill by watching others. It is a practice, like playing chess, or writing Math proofs. So IMHO the only way is to train. Start with simple problems, and continue from there. Bang your head against problems for a few hours before looking up the solution. Over time, you will get better.

Disclaimer: I'm myself not very good at algorithmic puzzles. For a job application I took a vacation to train solving coding tasks, and was getting better every day. I got that job, but guess that for a Google application I'd rather have to train for 3 months.

Here's one: https://www.youtube.com/watch?v=XKu_SEDAykw&t=11s

>They just told you how to solve it. But I can't see how they approach to get the answer. I think that part is the most interesting and valuable part for non-talent like me.

I ran into this too when I was preparing for a loop, especially for more complicated DP and recursion problems.

I found a website called gorecursion [0] on Reddit and he is very good at describing these solutions from the naive case to the optimized case very well. This helped me quite a bit, but I still didn't get the offer.

[0]: http://www.gorecursion.com/