In my opinion, the best way to train is to give yourself time with a problem. Read a problem statement, think about it intensively for about half an hour and then do one of 2 things :

a) you want to still study — in that case go the the next problem and read its statement, try to work on it too. only once you slept on a problem go check other solutions b) take a break and go for a walk, do some housework or something. the solution often comes during such mundane tasks and it's much better if you come up with it rather than seeing the other solutions

Also, reading editorials is better than seeing other's solutions (just google "round X editorial" and it should pop up as top result usually, the solutions there also include explanations why things work)