We will hold 【MX-X6/J7】Mengxiong Weekly (Open) on Luogu. This is a Div.1+Div.3 round provided by our collaborator. If you cannot understand Chinese, ChatGPT may be helpful.
- Contest URL:
- Start Time: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20241003T1330&p1=237
- Duration: 270 minutes
- System: IOI
- Difficulty: Similar to Codeforces Div.1 and Div.3
- Writer & Tester: Sol1, ChenKaifeng, A_zjzj, hhoppitree
- Rated Range: Unrated on Luogu
- The points value:
- Div.1: 100-100-100-100-100-100
- Div.3: 100-100-100-100-100
- The Div.3C will be Div.1A, Div.3D will be Div.1B, etc.
We are looking forward to your participation! If you cannot understand Chinese, ChatGPT may be helpful. We are working on establishing an English platform, but it takes time. We plan to complete this task by the end of 2024 or early 2025.
hope the adminers of luogu will not use their website to play genshine
hope the adminers of luogu will not use their website to play florr.io
tang
Thanks to MengXiong and Luogu for the quality contest.
qpzc
At first I thought the contest looked very early due to different time zones, but it seems that the contest is at 13:30 even in China? Is that a time when Chinese people are usually free? I'd assumed that they would either be at school or work.
Is luogu good to practice on?
It's our National Day and most of us are on holiday
And this year, our National Day holiday is from Oct. 1st to Oct. 7th
But some students in China can only have a three-day vacation.
But some students in China can only have a less-than-half-day vacation. Guess who.
Is Hunan Normal University so miserable?Senior 3rd students in my city can have a 4-day off.I'm in Nantong,Jiangsu.
Why you are in China,From Nanjing Foreign Language School?You should know it
It's during the National Day holiday,isn't it?
he is a Chinese.
How to E?
If the operation 3 is global (subtask 3), we can maintain a binary trie (separate by the lowest bit first) with lazy propagation.
In general, we cut out a subtree, add some value for it, and put it back into another position. We might need to merge it with an existing subtree, but we can just merge them recursively in amorized $$$O(1)$$$ time (potential: number of nodes. reference).
Great contest. T2 is really interesting. I stucked in T3.
Can we submit after the contest is over ?
If yes, then how ?
It'll have to wait until the administrators add the problems to the main problem archive. After that, one may submit a problem when accessing it from the archive.
upd. I've bumped the administrator, it should be available now :)
I got accepted for Div1F with $$$O(\sqrt{q} (n+q) \log(n+q)^2)$$$ time (in < 1 sec).
When $$$n$$$ is large enough, I checked every vertex which has a monent to have degree $$$\ge n-2$$$. There are $$$O(\min\{ n, q/n \})$$$ such vertices. For each vertex, since I didn't have a suitable link cut tree or something, I calculated the cost with 2 logs using offline dynamic connectivity. I feel like it might be as fast as 1 log.
Is it indeed that fast or there are not many tests with about $$$\sqrt{q}$$$ key vertices?
Indeed, I did not anticipate this solution and therefore most tests (unfortunately) have $$$n\geq 10^4$$$. I think I had put in a few tests with something around $$$n=500, q=3\times 10^5$$$ (and I switched root every $$$3n$$$ operations or so) just in case, but it was not specially constructed against this solution, so the amount of key vertices may still be small.
The reason for the TL to be 5s is that one of the testers wrote a self adjusting top tree which needs ~4s, and none of our testers (nor me) thought of anything between $$$O((n+q)\log^2n)$$$ and $$$O(nq)$$$.
Is there an editorial for these problems ?
If yes, where can I find it ?
Yes, but you may have to wait for one or two days. Editorials in Luogu isn't very fast.
If you do need editorials, I wrote some. But maybe it's not very easy to understand for all people. You can wait for some days to click the editorial button the right side of the problem.
Div1 A: https://www.luogu.com.cn/article/ic0v1k78
Div1 B: https://www.luogu.com.cn/article/vahdct0r
Div1 C: https://www.luogu.com.cn/article/8okz56xr
Div1 D: https://www.luogu.com.cn/article/ym0anhxw
And I can't solve Div1 E&F.