zhiyangfan's blog

By zhiyangfan, history, 2 days ago, In English

`I am trying to solve https://codeforces.cc/gym/103470/problem/K.

My solution is similar to the official tutorial(If you don't understand Chineses, it's ok! I write annotation in the code),but I'm troubled with constant factor(maybe not? If my time complexity is not good enough, please point out. qwq ), keeping getting TLE on test 38. :(

I wonder if someone can help me with it, pointing out something wrong with my implementations. qwq

My code.

 
 
 
 
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2 days ago, # |
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Your code has complexity $$$\Omega(\sum \deg^2)$$$ (which could be $$$\Omega(nm)$$$ worst case) for counting $$$C_3$$$ and $$$C_4$$$.

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    2 days ago, # ^ |
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    Why? qwq

    I think my code is using the proper way of constructing the new graph and can decrease the time complexity to $$$\mathcal{O}(m\sqrt{m})$$$. qwq

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      2 days ago, # ^ |
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      Ahh, I'm sorry. You're probably right. Then you might want to remove the hash table since it's not very efficient.

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        2 days ago, # ^ |
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        But without the hash I can't know how many times every edge is contained by $$$C_3$$$, for it requires a way to know the id of an edge with the vertices. qaq

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          2 days ago, # ^ |
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          Just store the indices (such as changing the vector to vector<pair<int, int> >) while storing the endpoints owo

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            2 days ago, # ^ |
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            That's amazing! Thank you so much for help!!