Some A's and B's can be quite tricky for some people, actually, since they usually focus on little tricks and observations that even some experts and higher can miss. A good way to practice might be to focus mainly on more complicated problems, but sometimes solve A and B to train your speed on simpler problem.

Yes, it happens.

I once as a low expert was able to solve Div 2 B and Div 2 C in an official contest. And I wasn't able to solve Div 2 A lol.

Sometimes A , but the chances of getting stuck on B are more than that of A

And it's a disadvantage, specially when you are the type of guy who can't move to the next problem without solving the current one , just like me ...

Yes it happens , many times. Also if you know cricket then the same scenario can be mapped as Master Blasters like Sachin Tendulkar getting bowled on very first bowl which happened many times.

Yeah. It happens sometimes. Once I solved A, C and D in a global round but couldn't solve B.

Check My history :(

Yes. I've stucked at B several times.

Yes, and I think usually it's for one of two reasons. I'll even limit myself to just Div2A problems in recent memory.

(1) The problem statement is complicated, confusing, etc.

• In my opinion these kinds of issues should be caught or fixed earlier in the development stage of a contest.

• This can be further described by some (not necessarily mutually exclusive) subcategories.

1a. The setup/game/premise in the problem is (relatively) somewhat convoluted and described in an unclear way.

1b. It contains a lot of information, values, and variables to keep in working memory, which can get overwhelming or confusing.

1c. The wording of the problem could have been phrased less ambiguously (understandable, since technical writing is hard especially when English is not your first language).

1d. The problem statement is just long.

(2) The problem requires a simple insight which ends up not being as obvious as the problem setter and coordinators had expected. Thus, the problem is genuinely difficult.

• Gauging the difficulty of an insight is difficult, so I find this more understandable.

• I actually like these types of insight-based problems (see discussion here) but I understand that it can be frustrating for people who just aren't able to see it.

2a. The problem is guessable, but an actual formal proof is more involved than usually expected from a Div2A problem. This trips up people who refuse to do "Proof by AC".

Anyway, here are some examples from the past few months, in no particular order, with a less-than-usual solve rate and/or higher-than-usual difficulty rating. I don't want to call out any problem setter as having bad writing, since I respect that making a problem set takes a lot of work and not everyone should be expected to be masterful in English, especially in technical writing. Still, I think you can make your own judgments on which of the following problems are hard to read and which are actually hard.

1393A - Радуга, Флаттершай и шахматная раскраска

1354A - Будильник

1339A - Заполнение ромбами

1366A - Лопаты и мечи

1373A - Магазины пончиков

1365A - Игра с таблицей

1364A - XXXXX

I solved my first D(div — 2) a few contests back :P(The last educational round if i remember). Sometimes E with no B other times E with no C but mostly A, B, C are easy enough(atleast if you can't solve then make a reasonable guess)

Yes, In Ashishgup rounds.

Yes.

Bonus

Yes I personally have such experiences. Especially when Div2B is implementation-heavy than usual, because I am really bad at coding. I personally hate when Div2B problem is about some $$$H \times W$$$ sized 2D-grid and inputs are bunch of * and # characters, since I mess them a lot. This occasionally happened even after I reached 2000+ rating. (Mostly this is because of my laziness which makes me not practicing implementation enough)

(Edit: I found it) Here is an example lol

I had no idea how to solve Div2B except using Fenwick Tree. I just used my library code and got AC without that much difficulty, but I felt very bad about myself unable to think and come up with intended proper solution when it isn't that difficult.

For advice, I recommend solving Div2A-B level problems until you are comfortable with those. Topic-wise practicing would not help much since there are not that many diverse topics in Div2A-B level problems. I personally recommend E869120's training method link even though there were some disagreeing comments back then.

Yes. How can I forget this.

I remember sitting idle, staring at the screen, rapidly switching questions A-to-B, B-to-C, C-to-A. Panicked because of not being able to solve even a single question, and came out of the contest, bare-handed. The thing is not to get demotivated and try harder in the next contest.

In one Div3 contest, I as a candidate master was not able to solve A.

This one is really bad, couldn't do B in 33 minutes.

Speaking only for myself, occasionally I’ll get them wrong on the first submit or fail system tests because my solution wasn’t actually right and I didn’t think for long enough, but I almost never get stuck on them for a long time.

Here

yes, in the last contest I got huge rating drop because I was stuck on problem A for nearly 40 minutes and did not move to next problem which I found easy.