I used a Fenwick Tree for all of problems E, F and G.

Thank you for testing my code. In fact, the test cases I provided earlier were actually my own counterexamples, but they were illegal data. My code was also developed without the constraint that $$$a_i \lt = X$$$. I made a mistake in interpreting the constraints of the problem.

Sorry, I overlooked the restrictions of the question. Nevertheless, I still feel that my code is not quite correct.

Why is hacking of question C prohibited? I passed the test 346709015, but I later discovered that there were issues with my code, such as 1 4 4 3 3 3 10 The answer might be 19, but my output was not that.

In fact, it's the same. Because in your situation, there must be $$$p_{i-2} \gt p_i$$$. So whether it's for $$$p_i$$$ or $$$p_{i-1}$$$, they are both the second to last element. The impact on the subsequent part is the same.

Why did D come up with the idea of binary search? Who can prove the continuity of the answer? I feel that I cannot understand the correctness of binary search.

I think the solution to D is too vague, and doesn't explain the specific meaning of the dist array!

Can we determine the answer by asking for three vertices For problem C

Thanks to this competition for making me an expert。

C feels amazing, I can only think of BFS to solve it

I got wa three times for this

How to prove that C's approach is correct

What a pity. I could have made a D

I agree. Div2C is a great idea

Don't lose heart. Keep in touch and you'll be able to solve it easily

Who can tell me why my friend passed the question in the contest but didn't get A rating change (not 0)? Another friend of mine checked question A 7 times but didn't get A rating change either. Who can tell me the scoring rules? thank you

Thanks to div2, I became a pupil

The heart is too anxious to miss green name. Too many penalties。 But the experience is better