What does the following code calculate?

Question

ruby

At the same time, I'm trying to figure it out myself, but suddenly someone is familiar with the language. I google every method.

a = 2187
  v = ->(x){(0..2).to_a.repeated_permutation(x)}
  v[a].map do |r|
    f,l = [-1],0
    (1..2*a).each do |j|
      i = f[j-l-1]
      while i != -1 && r[j%a] != r[(l+i+1)%a]
        l = j-i-1 if r[(l+i+1)%a] > r[j%a]
        i = f[i]
      end
      if i == -1 && r[j%a] != r[(l+i+1)%a]
        l = j if r[(l+i+1)%a] > r[j%a]
        f[j-l] = -1
      else
        f[j-l] = i+1
      end
    end
    r.rotate(l)
  end.uniq.count do |r|
    v[7].count{|s|(0...a).map{|l| r.rotate(l)[0,7]}.include?(s)} == a
  end

Answer 1

Some complex calculations are going on here. Without context, or without knowledge of the relevant mathematical algorithms, it is difficult to understand. It's like generating a huge matrix and processing it.

Answer 2

It looks like the result of an obfuscator, to be honest.
Not so much complex calculations as highly confusing. Maybe linear algebra or discrete mathematics.
There are such metamorphoses in the code that it’s even scary to imagine why this is necessary
. If this is real code, such a developer needs to unscrew his hands.
It is also possible that the code is needed to waste computing resources.

Answer 3

maybe 42?

Answer 4

nadom , can you help? how is the graph given here if it is a problem of finding a Hamiltonian cycle?