I checked my old emails. In 2021, it was a 5-month window to claim the t-shirt.

I am still grateful for Meta to host such event. But it feels so Meta that it does not worry about its reputation.

This is such a short notice period. I didn't even receive an email notification. Only see the post today.

Another test cases:

1
4 4
1 2 3 4
4 4 1 1

I got confused.

Is it correct that "first" means first suffix from the right direction (shortest suffix)? Reasoning is that after A's move, whatever move B takes, makes the remaining string more A than B.

Would the administrator check the editorial link? The URL is stale now. Thanks in advance.

It took me a while to understand, and I do not think the time spent is worthy. Other ideas are better.

As I understand, it involves the following steps:

original string (s1) --> flipped even positions (s2) --> arbitrary swap (s3) --> flipped even positions again (s4).

• s2 is determined by s1, and we can count the number of ( as "plus" and the number of ) as "minus".
• s3 is of a particular form -- one (, minus copy of ), plus-1 copy of (.
• s4 is then a regular string.

The flip is hypothetical so it is not reflected in the code.

Range Interval Queries can also be solved using Binary Indexed Tree.

#elements with index in range [l, r]

= #elements in the whole array

- #element in the range [1, l — 1]

- #element in the range [r+1, n]

Each item on the right of the equation can be calculated separately with sorting of the queries.

So AI can solve 5 (almost 6) problems? Is AI so good now?

I often found it retarded for some simple problems. A little indirectness in the statements can break the AI.

In my experience it mostly worked for problems where the difficulty lies in the implementation of complex algorithm.

Am I outdated?

Thanks so much for your reply. sorry for my stupidity.