Hello, Codeforces community!

Today's contest was a nightmare for me. Let me tell you what happened.

First of all, I was 2 minutes late due to the networking issue. When I start the contest, 1000+ contestants already solved A. This made me extremely stressed.

I eventually calmed down, and passed both A and B in 15 minutes.

The next problem is C, which looks very trivial. However, I did not expect that I got stuck and could not figure out the solution in 20 minutes!

So I had no choice but to go and look at other problems.

My English is not that good. So I chose problem E, the one with the shortest problem statement.

I found it unbelievably easy and solved it in just 10~15 minutes.

Now I still have 75 minutes left.

I looked at D. Very easy, I can just use some STL (std::map and std::set) and binary search to solve it. However, it might took me a while (like 20~30 minutes?).

I looked at F. Seems not so difficult as well.

By the time, around 2000 contestants passed C. I thought "Maybe I overcomplicated the problem. I should be able to rush it." So I decided to work on C, which might be the stupidest mistake I made today.

I got stuck for another 40 minutes despite I already found out that x is equal to the greatest common divisor (GCD) of all the difference between adjacent elements.

20 minutes before the contest is over, I finally finished the code. However, since I initialized the maximum element of the array to be 0 (actually it should be -10^9 because there are negative elements), I received 3 WAs, which cost me lots of penalty.

I eventually passed C around 5~10 minutes before the end of the contest and then I had no time for D and F...

This is not the first time that I being destroyed by "easy" problems....

In Codeforces Round 903 (Div 3), I solved everything but C (which is a 1200 rating problem).

In Codeforces Round 907 (Div 2), I solved problem F (2000 rating problem) but failed to solve C (which is a 1500 rating problem), again.

In Codeforces Round 910 (Div 2), something even crazier happened. I solved D (1900 rating problem) and E (2200 rating problem) while failed to solve both B (1500 rating problem) and C (1700 rating problem).

So I am just wondering, what should I do to be good at solving Div2 B and C?

Also, I observed that there is an extremely big difference between OI and Codeforces/ICPC. I actually had some OI backgrounds, but it seems that my past experience can't help me do well in CF contests, at all.

Sincerely, I am looking for your suggestions (especially those who also had problem solving trivial problems before, or those who did OI in high school).

Also, I hope someone can help me with the writings of this post. I am pretty bad at English, as I said.

Thanks in advance!

Solve (1200-1400) for improving in B and C.

that's joke, right?

Most OF THE 2 problems are from 900-1100. Most of the C problems are 1200-1500 (sometimes 1600-1700). I became pupil by solving problems of just 1200 difficulty .

he doesn't need to practise this problems, he got unlucky

just practice more, you've done well in your few contests so far, you'll get used to the style of these cf tasks fast.

Just accept the possibility of losing your rating, it will ease your mind and help you to better concentrate on the problem

Why so many downvotes?

I am not writing this blog to gain attention or win contribution. I am just looking for some advice.