I've been using Anki in the last 3 months for "re-solve" leetcode questions. This way, I can apply new techniques for solving problems that I already solved in the past.

How it works

1. I attempt to solve a problem in leetcode.
2. After I solved it, I create an Anki card with the name of the problem, the leetcode url, and a couple of personal notes about it.
3. Then Anki makes sure to ask me this question in a couple of days.

Why it works

I have noticed that sometimes, I am not able to solve an already solved problem. So the "spaced repetition" technique is great for making sure I truly understand how to solve a problem. Yes! you can just go ahead an memorize the solution, that's up to you, however, that's not the idea. The idea is that you can apply "already-learned" techniques to solve the problem at hand.

I've seen an improvement already in the way I approach problems, and how I apply new techniques for solving problems that I solved in the past.