It is also a good idea to work on three hard level algorithm a day, one for morning, one for afternoon, one for evening. There are over 150 hard level algorithms, it is a good idea to stay updated with Leetcode.
One idea I got from the peer before is to read the problem statement first, do not look at the answer, let myself to think about the algorithm at least 20 minutes.
Here is the blog related to the algorithm.
It is related to binary index tree. I read the blog 10 minutes, and I also plan to read discussion panel for one or two solutions. That is it.
Here is very good link to read from Leetcode discussion. And then I found a good article to read as well.