What do you do when you can't solve a problem in a contest? Do you try to upsolve afterwards? How? How long do you try?

Are there any topics you regularily have problems with? which are they?

• Practice more problems and read tutorials.

• Take part in more contests.

• Find a friend to learn together.

• Go and learn Binary Search!

solve C-D div 2

This may be helpful https://codeforces.net/blog/entry/102617 .

You're caught in 1400-1500 means you can solve A,B easily & C takes time,can't solve D. To be an expert,You need to solve D.So try to solve 100+ D & do virtual contest regularly & upsolve D after contest regularly.

I was stuck in the 1500-1600 rating range for quite a long time. I used to "solve" 1900+ rated problems still my rating didn't increase. Then I changed my practising technique. Instead of "solving" 1900+ problems I started solving 1700 rated problems. Then I increased it to 1800 problems and so on. I increased when I found a rating range too easy for me. Since then my rating started increasing. What was the reason behind it? Before I changed my technique I really wasn't solving 1900+ rated problems. They were too difficult for me. I could solve some problems. But most of the time I used to get stuck in a problem for quite a long time. Then I would read the editorial, and then "solve" it. So My suggestion would be to solve problems that are difficult for you but not too difficult so that you can solve most of the problems without reading editorials.