Hamming numbers

# title: Hamming numbers
# source: https://rosettacode.org/wiki/Hamming_numbers
# category: Rosetta Code
# difficulty: Intermediate
# summary: Generate the opening Hamming numbers with the classic 2-3-5 pointer technique.
# tags: popular, math, sequences, dynamic-programming
# vibe: 0.2

def hamming_numbers(count)
  values = [1]
  by_two = 0
  by_three = 0
  by_five = 0

  while values.size < count
    next_two = values[by_two] * 2
    next_three = values[by_three] * 3
    next_five = values[by_five] * 5

    next_value = next_two
    if next_three < next_value
      next_value = next_three
    end
    if next_five < next_value
      next_value = next_five
    end

    if next_value != values[values.size - 1]
      values = values + [next_value]
    end

    if next_two == next_value
      by_two = by_two + 1
    end
    if next_three == next_value
      by_three = by_three + 1
    end
    if next_five == next_value
      by_five = by_five + 1
    end
  end

  values
end

def run
  values = hamming_numbers(20)
  {
    first_twenty: values,
    twentieth: values[19]
  }
end