How to learn a hard level algorithm on Leetcode?

Feb. 7, 2018

Introduction

I chose to work on Leetcode 301: remove invalid parentheses, and then I spent 30 minutes to work on the algorithm last Saturday Feb. 3, 2018. And this past Tuesday night I browsed all the blogs and then I found that I worked on the algorithm last July 2017. So I was so surprised and then I had to look into what is going on. How come I do not have any clue that I work on the algorithm over hours.

I was so surprised to read my own blog and then just amazed that how time can take away everything. Hard work and long journey of coding, design and study. Here is the blog dated on July 2017. I even wrote an answer in discussion and then got 3 reputation. I did not aware that I had positive reputation, last time I checked I only have zero reputation.

How to learn a hard level algorithm? 

It is important to practice again and again on the same hard level algorithm. My last practice in July 2016 seems not working very well, because I could not remember too much detail about how to write recursive function, tips and tricks.

This time I changed the plan. I like to focus on more on ideas. I tried to write more than five blogs for each idea of the algorithm, and write down my own notes for each idea. Hopefully I can learn more things from one hard level algorithm.

There are so many algorithms, I can not work on a lot of them. Just get familiar with hard level one.

What I like to do is to leave 10 discussions comment for other people's post in leetcode discussion panel, and also vote up to 10 ideas to encourage people sharing. Get involved more about sharing ideas on the hard level algorithm. Do not be biased on ideas.