This is my first blog on Codeforces. I am on the "specialist" level only and probably I don’t have enough ability to make a great contribution. I can only share my experience of the contests I have already taken.
To begin with, I am grateful for Codeforces because its unique rules help improve my coding ability. The judging criterion In Codeforces is special. The unacceptable submissions and resubmissions can both reduce my score. So, I have to submit code carefully and try my best to resubmit less. And because of the hacks, there are no problems with weaken test data. Unlike other competitions, the test in the contest of Codefores is only "pretest". Therefore, the hacks not only provide a good environment for the interactions between competitors, but also strengthen the data by the way. The problems in Codeforces are also constructive. All the rules make competitors to think more and use own ideas instead of only using data structures directly.
Then, I want to share my experience: the psychological effect on coding. I am "specialist" now as I said, and I think I will soon become "expert". It is important for me to surmount D problem in Div.2. Actually, in recent days, I have solved many D problems in the past contests and the problems with similarly difficult level in the problem set. However, I have solved only one D problem in the real time contest (without hacks). Why cannot I always solve the D problems (in Div.2)? I think the psychological effect influenced me. Since Codeforces pays attention to constructive ability, many competitors cannot solve problems of the same difficulty level stably. How does the psychological effort impact? For example, faced a D problem in one of the recent contests I joined, I discovered that there were only few people’s coding were accepted. Based on my thought that I cannot solve D problems neither, I finally did not solve it successfully. Another contrary example was that, in the problem set, noticing some C problems or even B problems were all in Div.2 together with D problems, I guessed the D problems were as difficult as the B and C ones, and my confidence to resolve the D problems was greatly improved. Therefore, we need to try our best to avoid the bad influences of psychological effect!