collatz.rb

class Collatz

  def initialize(n)
    @current_number = n
    @sequence = []
  end

  def compute_next_collatz
    @sequence << @current_number

    if @current_number == 1
      return @sequence
    elsif @current_number % 2 == 0
      @current_number = @current_number / 2
      compute_next_collatz
    else
      @current_number = @current_number * 3  + 1
      compute_next_collatz
    end
  end
end

def longest_collatz(n)
  longest_sequence = { number: 0, length: 0 }

  1.upto(n) do |ceiling|
    sequence = Collatz.new(ceiling).compute_next_collatz
    # ceiling 1 -> sequence: [1]
    # compare to current longest_sequence:
    # longest_sequence = { number: 1, length: 1 }
    #
    # ceiling 2 -> sequence: [2, 1]
    # compare to current longest_sequence:
    # longest_sequence = { number: 2, length: 2 }
    #
    # ceiling 3 -> sequence: [3, 10, 5, 16, 8, 4, 2, 1]
    # compare to current longest_sequence:
    # longest_sequence = { number: 3, length: 8 }
    #

    # code to write
  end


  puts "The longest collatz sequence from 1 to #{n} is the sequence for the number #{longest_sequence[:number]} and has the length of #{longest_sequence[:length]}"
end

longest_collatz(5)