atcoder_official's blog

By atcoder_official, history, 4 weeks ago, In English

We will hold Tokio Marine & Nichido Fire Insurance Programming Contest 2024(AtCoder Beginner Contest 355).

We are looking forward to your participation!

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4 weeks ago, # |
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Hoping to solve ABCD!!

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4 weeks ago, # |
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There is a strange bug on the homepage of ABC355. If you're in English mode, when you enter the page, your browser begins playing music; after that, there will be some Japanese introduction to this company.

I found that the problem was caused by the video on the homepage (in Japanese mode), and the solution is to ban your browser from automatically playing media on the page. And I hope AtCoder can fix it. This is not a big problem, but sometimes it's annoying.

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4 weeks ago, # |
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i think problem D is close to this problem

atcoder's solution

codeforces solution

the only difference is that codeforces's problem one interval should contains the other.

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4 weeks ago, # |
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Misread B :)

Btw, how to solve F? Does it involve link-cut trees?

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    4 weeks ago, # ^ |
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    this can be extended easily for F

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    4 weeks ago, # ^ |
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    maybe yes , I just opened cf 5 minutes before the contest ended and saw a blog come up on MST query. I saw a GM explaining to use link cut trees. I started to read it and knew it was not of my cup of tea at least for my level.

    LMAO

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    4 weeks ago, # ^ |
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    I solved it with basic Kruskal's algorithm, by looking at the constraints.

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4 weeks ago, # |
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found very difficult.

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4 weeks ago, # |
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My idea for problem-E using dp find the minimum no of moves to reach from L to R, then get the path. I'm getting WA.

Code

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    4 weeks ago, # ^ |
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    i did not read your code, but you took into consideration right that we can also add and reduce values not in range L-R for example if 1-7, we can add 0-7 and sub 0-0?

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4 weeks ago, # |
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SpeedCoder?

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4 weeks ago, # |
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Anybody missed reading the constraint on weight in F and then waste time?

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4 weeks ago, # |
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Cool.

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    4 weeks ago, # ^ |
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    Cool.

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    4 weeks ago, # ^ |
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    he/she needs only a minute to finish four problems!? That's really insane, and also suspicious.

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      4 weeks ago, # ^ |
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      Maybe I don't get something, but it took him 51 minutes to solve ABCD?

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      4 weeks ago, # ^ |
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      No, they just have a really good gaming chair.

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    4 weeks ago, # ^ |
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    Is there any extension for atcoder as well which predicts rating change ?

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    4 weeks ago, # ^ |
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    I checked toyuzuko's contest history. Their last contest was ABC354 and they solved ABCE in less than 2 minutes, but they registered as unrated and didn't get reported. I didn't find any abnormal contests before that.

    maroonrk could you please figure this out

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    4 weeks ago, # ^ |
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    Cool.

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    4 weeks ago, # ^ |
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    Cool.

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      4 weeks ago, # ^ |
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      Another conjecture is that he may have used very intelligent AI due to some unnecessary annotations.

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    4 weeks ago, # ^ |
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    2 weeks ago, # ^ |
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    It's quite interesting (and suspicious?) that they also added comments to their code...it implies that they weren't rushing, yet they solved all the problems almost immediately??

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4 weeks ago, # |
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Is there any other solution apart from link-cut tree? I didn't know about link-cut tree so did a brute force kind of solution.
I processed initial N-1 edges from lowest weight to highest weight. For each weight, I maintained connected component data using DSU.
Then for each additional edge of weight W to add, I checked if nodes U, V are in same component at DSU of weight W. If they are that means, an edge with weight <= W has connected components of these two nodes so the incoming edge can't replace any edge in MST.

If they are in different components, then that means, components to which U, V belong are connected by some higher weight edge and incoming edge can replace heavier edge in MST and update MST edge weight and then do union for U, V for all edge weights greater than or equal to W.

I got an AC with this approach but not sure if this approach is correct as everybody is mentioning link-cut tree. Can someone confirm if this is correct?

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4 weeks ago, # |
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Why does this solution to D gives WA (https://atcoder.jp/contests/abc355/submissions/53878525)

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4 weeks ago, # |
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For problem E, is there any intuitive understanding about the definition of S(x,y) = -S(y,x) when x > y.

I wonder how could someone come up with this definition and construct a graph.

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4 weeks ago, # |
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When will the Editorial in English be available?