Roman Numeral to int

rom_to_int.rb

def rom_to_int(input, total=0)
  return total if input.length === 0

  roman_numerals = {
    "I" => 1,
    "V" => 5,
    "X" => 10,
    "L" => 50,
    "C" => 100,
    "D" => 500,
    "M" => 1000
  };
  
  if input.length > 1 && roman_numerals[input[0]] < roman_numerals[input[1]]
    total += roman_numerals[input.slice!(1)] - roman_numerals[input.slice!(0)]
  else
    total += roman_numerals[input.slice!(0)]
  end
  
  rom_to_int(input, total)
end

puts "MCMXCIX => #{rom_to_int('MCMXCIX')}"
puts "LXXIV => #{rom_to_int('LXXIV')}"
puts "DCCCXC => #{rom_to_int('DCCCXC')}"
puts "IV => #{rom_to_int('IV')}"