Currently there is a option for to-do list ie problems which we have not solved yet. It would be great if this could extend for solved problems also. We could add those problems into the list which we liked even after solving. So, I request you to add this feature.
@admin
Thanks and Happy New Year
Thanks - that’s not something we’ve considered so far, and would definitely be a useful addition. We’ll look into this.
Happy new year 
What UI improvements do you want? Ask/suggest admin for that.
The UI is inconsistent at multiple sections (see forgot password or blog.codechef.com for example). Mobile rendering of the main site is poor (read absolutely shitty).
The unacademy site looks sleek, so I’m hoping they’re working on a revamp.