Before the start of the blog, I'd like to thank this blog for motivating me to write it.
However, this blog is quite outdated in many factors like the rating system, and people starting cp in 2020 may have trouble following these. Therefore, I would like to write new tips for doing well in codeforces. The goal is getting to candidate master, or rating 1900.
I would write this in 4 steps, but the most important thing here is Practicing hard. You won't get to 1900 if you don't practice, you don't have to do it on the blog's way, but you should practice.
Step 1: from 1000(grey) to 1200(green)
First, read introduction to the new rating system and judge your skill. Note that you'll need to take part in about 5 contests to judge your skill. If your rating is under 1200, read the next part and practice.
If you use div3, you'll need to solve 3 problems in 30 minutes. That means you should solve div3C in 15 minutes. To practice it, you may choose 1000~1200 rated problem and try to solve it in 15 mins. If you have no idea in 15 mins, you should see the editorial.
If you use div2, you'll need to solve 2 problems in 30 minutes. The practice methods are the same, but do it in 1100~1300 rated problems and 20 mins.
Step 2: from 1200(green) to 1400(cyan)
In order to get to cyan, you should know basic dp, greedy, bit operation, and math. Other things such as graph theory are not required to go to cyan.
First, you should learn about the algorithms. First, you need to know the concept of them, and you should practice. Practicing these algorithms can be done by solving 1300~1500 rated problems having these tags.
You need to solve 4 problems in div3(You don't need fast solving) or 2~3 problem in div2(highly depends on difficulty, if it's 2 problems, you need to do fast solving). I would recommend to solve 1300~1600 rated problem(you can tag search them), and try to solve them in 15~30 mins, and see editorial after 30 mins.
Step 3: from 1400(cyan) to 1600(blue)
Rating 1600, or the title "expert", requires quite a lot of algorithm knowledge. You need to know bit advanced form of former four, graph theory, sorting, and binary search.
Again, you need to study these algorithm, the methods are similar to that of the cyan
