topaa's blog

By topaa, history, 2 months ago, In English

Hi, This is my first blog. I encountered a problem PAROVI few days ago, but I am not able to solve it. Any ideas on how to proceed? Thankyou.

 
 
 
 
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2 months ago, # |
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Define by $$$f(l, r)$$$ the number of sets of pairs of relatively prime integers of $$$l, l + 1, \ldots, r$$$, and by $$$g(l, r)$$$ the number of sets of pairs of relatively prime integers of $$$l, l + 1, \ldots, r$$$ such that there is no $$$x$$$ among $$$l + 1, \ldots, r$$$ satisfying Slavko's constraint. Then we have the equality

$$$g(l, r) = f(l, r) - \displaystyle \sum_{k = l}^{r - 1} g(l, k) f(k + 1, r).$$$
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    2 months ago, # ^ |
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    Thanks. One small question, what should be g(i,i) equal to? Do we have to consider here that we can't construct a pair using same number and also empty sets are not allowed? In that case g(i,i) should be zero. But my code works only with g(i,i)=1. My AC submission

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2 months ago, # |
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124755941 could you please explain me this question ...