I have been working on do 1700 rated problems for a while, sometimes I can do it quickly, sometimes may not. However, I solve almost all problems without looking at the solution code or solution. For the few problems that are harder to figure out, I sometimes rely on long periods of thingk(even through I realize sometimes I engage in meaningless thinking) or use brute-force solution to generate data to correct my approach. But the final goal is Competition, it is not so useful way to solve hard C or D in Div2 in what I said.

Because of personality, I am afraid to participate in CP when I think I can not 100% sure to solve D in Div2. So I want to ask how I can improve.. I will take them into consideration if you can give me advices! Thanks!