First, No you don't have the knowledge barrier, maybe practice math a bit more but it's ok
for number theory: get away from them for now if u know nothing about it
third: try to build logic for greedy, constructive questions and simple math
don't cheat, please

fourth: you know I used to find 1300 problems really hard when I was a newbie
in pupil I found 1500 hard, now I find 1700-1900 problems challenging, 2000+ hard

see where I'm going with this, You'll always find something 100 200 more than ur rating challenging and more than that hard. and that's the whole logic, u get to a rating which u can find it's problem not challenging, not simple but not as challenging, like if I'm 1500 means that I can regularly solve 1500-1600 problems, and find them not challenging, maybe not easy but not as challenging, and I find the 2500 I solved very very hard, where i spent a week on it

Be consistent, don't overcomplicate it, don't cheat, and don't learn things more advanced than needed, like idk segment tree, fenwick tree any of that bullshit, but I don't face a challenge solving a problem bcuz of not knowing them

hope this helped

Try doing some parts of the AoPS (Art of Problem Solving) textbooks, or any other similar book. Not the entire thing though, the only math things you need up till ~1700 are:

• Basic manipulation of equations and inequalities (subtracting/adding something from both sides keeps the equation/inequality valid, multiplying/dividing something positive on both sides keeps the inequality valid, etc.)

• Number theory (congruences, prime factorization are basically the only two things you require)

• Basic combinatorics (addition/multiplication principle, pigeonhole, factorials, etc)

• Maybe a bit of graph theory, but you can learn that from CP textbooks like CPH (competitive programmer's handbook) as well

I think my input would benefit you and others so I'll share it.

I first started CP around 8 years ago. (I do regret not being more dedicated to training and maybe leaving CP behind for some years.)

Since I quit for a couple of years here's what I noticed:

I used to solve ABC before I quit and when I came back I barely solved B despite it not being a knowledge problem or math problem. It's just that the problems now are more logic-based which is a skill that needs sharpening and practice. Continuous practice to be exact, as leaving or not being serious about training will stop this growth and maybe have a negative effect. (You might think what you once learned will always be with you but that's too far from the truth)

What's working with me now is competing in AtCoder ABC rounds and every contest here on codeforces. And upsolve them. I might need to work harder on upsolving but even reading the tutorials thoroughly and understanding the solutions would make an impact (Even for the problems you solved)

unironically, i think "900" rated problems have genuinely become harder in last few years

I agree with u. It's so hard when u just start cp.

Yes, sir.