vinayaka's blog

By vinayaka, history, 10 months ago, In English

Hello, I'm trying to solve the problem movie festival II on cses problemset.

This is my code

My code

It gives AC on 9 cases and WA on 4.

This is success code from USACO Guide forum.

Success code

What am I doing wrong? Isn't set.upper_bound comparison same and pq.top in mine? Can anyone help in writing success PQ code?

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By vinayaka, history, 13 months ago, In English

Hi,

My knowledge on String algorithms is poor so I am studying it now.

I solved 271D - Good Substrings using a Trie, but I am trying to solve it using hashing.

I am able to calculate a polynomial rolling hash and compare substrings based on the hash, but my solution is getting WA on test 8 (230797737). I am thinking this is because of collisions, since the expected answer is also pretty high.

I read a topic on double polynomial rolling hash to reduce probability of collisions. I understand that if we use two hashes of order 10^9 then probability will be less because it is equivalent to using a 10^18 modulo.

I am unable to understand how to implement it.

Can anyone help?

Please point me towards an article/blog/submission that has code on implementing it.

Thank you.

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