Ethiopian multiplication

# title: Ethiopian multiplication
# source: https://rosettacode.org/wiki/Ethiopian_multiplication
# category: Rosetta Code
# difficulty: Intro
# summary: Multiply two integers by repeated halving, doubling, and summing odd rows.
# tags: popular, math, multiplication, loops
# vibe: 0.2

def ethiopian_multiply(left, right)
  total = 0
  a = left
  b = right

  while a > 0
    if a.odd?
      total = total + b
    end
    a = a / 2
    b = b * 2
  end

  total
end

def run
  {
    seventeen_thirty_four: ethiopian_multiply(17, 34),
    twenty_seven_eighty_two: ethiopian_multiply(27, 82),
    three_digit_pair: ethiopian_multiply(123, 45)
  }
end