csacademy's blog

Round #30 (Div. 2) + Special Prizes
By csacademy, 7 years ago, In English

Hello, Codeforces!

We are happy to announce that we're going to host a new contest at csacademy.com. Round #30 will take place on Wednesday, May/24/2017 12:00 (UTC). This round will be a Div. 2, meaning that the rating change will only affect users with a rating below 1650. Unrated users will also be affected. High rated coders can participate unofficially.

If you want to take part in this round you need to register before the contest begins. As this is a Div. 2, it will consist of 5 tasks of more accessible difficulty.

Special prizes

This round will have 3 special prizes consisting of private coaching lessons with our contest coordinator, wefgef. Each lesson will be conducted on Skype and will last for 1 hour and 30 minutes. The topics approached during the lesson will be the choice of the winners. The prizes will be distributed as follows:

  • 1 random prize for the top 20%
  • 1 random prize for the next 30%
  • 1 random prize for the bottom 50%

Contest format:

  • You will have to solve 5 tasks in 2 hours.
  • There will be full feedback throughout the entire contest.
  • Tasks will not have partial scoring, so you need to pass all test cases for a solution to count (ACM-ICPC-style).
  • Tasks will have dynamic scores. According to the number of users that solve a problem the score will vary between 100 and 1000.
  • Besides the score, each user will also get a penalty that is going to be used as a tie breaker.

About the penalty system:

  • Computed using the following formula: the minute of the last accepted solution + the penalty for each solved task. The penalty for a solved task is equal to log2 (no_of_submissions) * 5.
  • Solutions that don't compile or don't pass the example test cases are ignored.
  • Once you solve a task you can still resubmit. All the following solutions will be ignored for both the score and the penalty.

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7 years ago, # |
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Round #30 will take place on Wednesday, May/17/2017 12:00 (UTC).May 17 is already gone

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7 years ago, # |
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When do we get to see the test cases?

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7 years ago, # |
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How to solve E? Was this some classical Problem? I saw a lot of submissions but didn't seem trivial at all?

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    7 years ago, # ^ |
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    I considered the following nodes to be the answer, either the node themselves or the lca of every two nodes or the lca of all the three nodes. But it turned out to be wrong.

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7 years ago, # |
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How to solve D guys ?

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7 years ago, # |
  Vote: I like it +1 Vote: I do not like it

In D, I made a trie of the strings and noted how many words end at a node. Then i traversed the trie and whenever the word count just became greater than 0, I stopped the traversal in that node and put the length of the string uptil then in a vector. I sorted the vector and if there exits more than or equal to k elements, I outputted the k'th element else I output -1. What's wrong in this?

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