Phaeton's blog

Some interesting problems
By Phaeton, 9 years ago, In English

Hello Codeforces community!

I want to ask you to give links to problems, that you find interesting.

By "interesting" I mean problems that:

  • The solution wasn't about to code some very difficult algorithm, but mainly targeted at idea
  • The problem needs to think in different way. (i.e straightforward solution will be wrong)

It will be very good if the problem is on some OJ (like Codeforces, SPOJ).

Thanks!

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9 years ago, # |
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I tried something similar here but seems like nobody cares.

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9 years ago, # |
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http://wcipeg.com/problems/desc/coci096p5

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    9 years ago, # ^ |
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    As I understand the problem, there is two things we must notice 1. If he knows the implication A -> B , it means if A occurred, event B must have also occurred. 2. If any A -> B implication is true he knows that implication. Apparently I'm wrong because "2 3" is also correct according to this. Could you please tell me what am I missing ?

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      9 years ago, # ^ |
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      I'm assuming you're talking about the first sample case -- event 2 is true because it's known to be true (as one of the certain events).

      Event 1 is true because event 2 must have been caused by something, and the only cause for event 2 is event 1.

      Event 3 is true because event 2 is true, and event 2 causes event 3.

      Am I understanding your question?

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        9 years ago, # ^ |
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        I missed that "each event must have been caused by some event" part. But I still can't find it in the task description :D Thanks for the answer and the nice problem.

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