Solve AGC005D with NTT

Revision en1, by ez_zh, 2018-08-13 11:32:33

Problem link: AGC005D

You can use DP to solve this problem in O(NK).

This code got AC when N<=2000 and K<=N-1.

DP Solution (29ms)

Here is the editorial: Editorial

After I read the editorial, which explains the DP solution, I found this line below:

おまけ: 以上の考察をもう少し進めると、この問題は O(NlogN) で解くことが出来ます。

That means there is a faster way to solve this problem.

My friends has just found a NTT solution. It works in O(NlogN).

NTT Solution (2ms)

I hope it will be useful!

Happy coding!

Tags ntt, #atcoder, #problem

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en1 English ez_zh 2018-08-13 11:32:33 3159 Initial revision (published)