MagicSpark's blog

By MagicSpark, history, 4 days ago, In English

We can see that on the home page of atcoder there will be two contests in December.

They're agc050 and agc051(Both are Good Bye rng_58)

So could anyone tell me what happened to rng_58?

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By MagicSpark, 6 weeks ago, In English

I find that I can enable coach mode(there isn't a button when I open gyms)

So what's the condition of opening a coach mode?

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By MagicSpark, history, 2 months ago, In English

In Grakn Forces 2020,I ranked 75 and get a T-shirt according to KAN's comment(https://codeforces.com/blog/entry/82787?#comment-705409).

This is the first time that I get a T-shirt,but can somebody tell me how to get it?

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By MagicSpark, history, 6 months ago, In English

When I'm taking part in Educational Codeforces Round 87,I come up with a random solution.

But I didn't think it can pass.(In fact I'm wrong and the solution has more than 99.99% possibility to pass)

And I think for a long time to find a non-random solution without getting good ideas

Can somebody solve this problem?

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By MagicSpark, history, 16 months ago, In English

When I am solving 1197D,I didn't see m<=10 and then I find a solution that can solve m<=n<=3e5

Here is my solution:

The range [l,r] is equal to [l,l+m-1],[l+m,l+2m-1]....[l+xm,r]

then we will enumeration the value of l+xm.

We consider every reminder(from 0 to m-1) of position module m and solve them independently.

When we are solving each of the reminders,we have v[i]-->the value of the ith range(from the ith position fits the reminder to the next),then we will consider the value of two parts

First:[l,l+m-1],[l+m,l+2m-1].....[l+(x-1)m,l+xm-1]

Second:[l+xm,r]

We can use segment tree to get the max prefix sum of [l+mx,l+(m+1)x-1],then it's the second part.

When we are solveing the first part,we need to find the min value of the prefix sum of v[i].

This can also be done using segment tree.

Then the answer for each l+xm is First+Second-k.

Here is my submission https://codeforces.com/contest/1197/submission/57841454

The final answer is the maximum of them.

Overall complexy O(n log n) with big constants

I wanna know if there are better solutions.

If you have,please share under this blog.

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By MagicSpark, history, 19 months ago, In English

I tried to solve 1153F. I got up with an unusual idea.Then this is my code.I clone the 1153F to a mashup.And I accepted with maximum time 1825 ms.But the time limit is only 1 second. Can some one help me to optimize the code? (Because it is not so slow,I think I don't need to change the algorithm,And I only get this way to solve the problem) [submission:53500731] in the mashup and 53500951 in the contest.

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By MagicSpark, history, 21 month(s) ago, In English

When will the of educational round 60 be published?Usually there is only a few hours after the contest the tutorial will be published.But now, almost two days past,where is the tutorial? (Sorry for my pool English and poor rating.) Oh sorry it published.

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