Volunteering at RailsGirls Next

Spend the whole today at RailsGirls Melbourne. Met many great people and had fun. It's the first time I've done it and would recommend others to do it.

I was helping RailsGirls Next group and should say exercises were too difficult and boring as they require minimum coding and mostly mathematical logic.

Also got a funny card during ice-braker exercise

Below is my solution for the roman numerals exercise. Just like my observation earlier, I've spend most of the time thinking about logic for the solution.

# encoding: utf-8

DOZENS = {
  10 => ['I', 'V', 'X'],
  100 => ['X', 'L', 'C'],
  1_000 => ['C', 'D', 'M'],
  10_000 => ['M', "_", "+"]
}


def convert_single number, dozen
  one, five, ten = DOZENS[dozen]

  case number
  when 1..3
    one * number
  when 4
    one + five
  when 5
    five
  when 6..8
    five + (one * number)
  when 9
    one + ten
  end
end

def roman(number)
  number.to_s.chars.reverse.each_with_index.map do |char, index|
    dozen = 10 ** (index + 1)

    convert_single(char.to_i, dozen)
  end.reverse.join('')
end


require "minitest/spec"
require "minitest/autorun"

describe "roman" do
  it "converts the number 1 to the string I" do
    roman(1).must_equal 'I'
  end
  it "converts the number 1234 to the string I" do
    roman(1234).must_equal 'MCCXXXIV'
  end
  it "converts the number 4999 to the string I" do
    roman(3999).must_equal 'MMMCMXCIX'
  end
end