Rosetta Code

Aliquot sequence classifications

Build short aliquot sequences and classify whether they terminate, loop, or are perfect.

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Sourcerosettacode/popular/aliquot_sequence_classifications.vibe
def proper_divisor_sum(number: int) -> int
  if number == 1
    return 0
  end

  total = 1
  factor = 2

  while factor * factor <= number
    if number % factor == 0
      total = total + factor
      other = number // factor
      if other != factor
        total = total + other
      end
    end
    factor = factor + 1
  end

  total
end

def aliquot_sequence(start_value: int, limit: int) -> array<int>
  values: array<int> = []
  seen: hash<string, bool> = {}
  current = start_value

  while values.length < limit && !seen.fetch(current.to_s, false)
    values << current
    seen[current.to_s] = true
    current = proper_divisor_sum(current)
  end

  values << current
  values
end

def classification(sequence: array<int>) -> string
  if sequence.last == 0
    "terminating"
  elsif sequence.last == sequence.first
    "perfect"
  else
    "looping"
  end
end

def run -> array<{ classification: string, sequence: array<int>, start: int }>
  [6, 10, 12].map { |start|
    sequence = aliquot_sequence(start, 8)
    {
      start:,
      classification: classification(sequence),
      sequence:
    }
  }
end

Output

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